Ignition system DODGE RAM 1999 Service Service Manual

19) Turn ignition on. Using scan tool, read governor pressure
sensor voltage. If voltage is 4.65 volts or less, replace PCM. If
resistance is greater than 4.65 volts, go to next step.
20) Turn ignition off. Drain transmission fluid and remove
oil pan. Disconnect pressure/temperature sensor harness connector.
Inspect connector and terminals for damage. Repair as necessary. If
connector and terminals are okay, reconnect transmission solenoid
harness connector. Measure resistance of governor pressure sensor
signal circuit between White PCM harness connector C2 and governor
pressure sensor harness connector. If resistance is greater than 5
ohms, repair or replace transmission solenoid and harness assembly. If
resistance is 5 ohms or less, go to next step.
21) Measure resistance of governor pressure sensor ground
circuit between Black PCM harness connector C1 and governor pressure
sensor harness connector. If resistance is greater than 5 ohms, repair
or replace transmission solenoid and harness assembly. If resistance
is 5 ohms or less, go to next step.
22) Turn ignition on. Measure voltage between ground and
governor pressure signal circuit at governor pressure sensor harness
connector. If voltage is greater than one volt, repair or replace
transmission solenoid and harness assembly. If voltage is one volt or
less, replace pressure/temperature sensor.
23) Check and record freeze frame data to determine
conditions which set code. Conditions required to set DTC P1764 are
not present at this time. Using wiring diagram as a guide, inspect
wiring and connectors. Repair wiring harness as necessary. If wiring
and connectors are okay, go to next step.
24) Using scan tool, clear DTCs. While reading DTCs, wiggle
wiring harness between PCM and governor pressure sensor. If DTC P1764
resets while wiggling wiring harness, repair wiring harness as
necessary. If DTC P1764 does not reset, go next step.
25) DTC P1764 sets if governor pressure sensor input is less
than .1 volt for 8.36 seconds. Possible causes are: PCM internally
shorted or open, incorrectly wired, dirty or corroded connectors or
open or shorted wiring. See INACTIVE DTC CONDITION under SELF-
DIAGNOSTIC SYSTEM. Testing is complete.
DTC P1765: TRANS 12-VOLT SUPPLY RELAY CNTRL CIRCUIT
Circuit Description
Circuit is monitored continuously while key is on. Code sets
if voltage on transmission control relay circuit at PCM is different
than expected voltage for 3 seconds.
Possible Causes
* Generator source circuit open.
* Transmission relay control circuit open.
* Transmission relay control circuit short to ground.
* Transmission control relay wiring harness defective.
* PCM defective.
* Transmission control relay defective.
Diagnostic Procedures
1) Using scan tool, read DTCs. On AN and DN bodies, go to
next step. On all except AN and DN bodies, if DTC SPECIFIC GOOD TRIPS
counter is not displayed or displayed count is not "0", go to step 9).
If DTC SPECIFIC GOOD TRIPS counter is displayed and displayed count is
"0", go to next step.
2) Using scan tool, actuate transmission control relay. If
transmission control relay does not click, go to step 5). If
transmission control relay clicks, go to next step.
3) Wiggle wiring harness between transmission control relay

and PCM. Ensure scan tool is still actuating transmission control
relay. If transmission control relay stops clicking, repair wiring
harness as necessary. If transmission control relay continues
clicking, go to next step.
4) Using wiring diagram as a guide, inspect wiring and
connectors. Repair wiring harness as necessary. If wiring and
connectors are okay, see INACTIVE DTC CONDITION under SELF-DIAGNOSTIC
SYSTEM. Testing is complete.
5) Remove transmission control relay. Inspect connector and
terminals for damage. Repair as necessary. If connector and terminals
are okay, turn ignition on. Using scan tool, actuate generator field.
Measure voltage between ground and generator source circuit at
transmission control relay harness connector. If voltage is 10 volts
or less, repair open generator source circuit. If voltage is greater
than 10 volts, go to next step.
6) Turn ignition off. Measure resistance between transmission
control relay terminals No. 85 and 86. If resistance is 100 ohms or
greater, replace transmission control relay. If resistance is less
than 100 ohms, go to next step.
7) Disconnect White PCM harness connector C2. Inspect
connector and terminals for damage. Repair as necessary. If connector
and terminals are okay, measure resistance between ground and
transmission relay control circuit at White PCM harness connector C2.
If resistance is less than 5 ohms, repair short to ground in
transmission relay control circuit. If resistance is 5 ohms or
greater, go to next step.
8) Measure resistance of transmission relay control circuit
between transmission control relay connector and White PCM harness
connector C2. If resistance is 5 ohms or greater, repair open
transmission relay control circuit. If resistance is less than 5 ohms,
replace PCM.
9) Conditions required to set DTC P1765 are not present at
this time. DTC P1765 sets if transmission control relay is not in a
state requested by PCM for greater than 3 seconds. Possible causes
are: faulty relay, open or shorted control circuit, faulty PCM or
faulty connector terminals. Inspect all related wiring and connectors.
Repair as necessary. If wiring and connectors are okay, erase DTCs.
Using scan tool, read DTCs while wiggling wiring harness between
governor pressure sensor and PCM. If DTC P1765 resets, repair wiring
harness as necessary. If DTC P1765 does not reset, see INACTIVE DTC
CONDITION under SELF-DIAGNOSTIC SYSTEM. Testing is complete.
DTC P1899: P/N SWITCH STUCK IN PARK OR IN GEAR
Circuit Description
Circuit is monitored with transmission in "D", "N" or "P"
position. Code sets if PCM detects an incorrect park/neutral switch
state for any given mode of vehicle operation.
Possible Causes
* Park Neutral Position (PNP) switch wiring harness
defective.
* PNP switch sense circuit open.
* PNP switch defective.
* PNP switch sense circuit short to ground.
* PNP switch stuck.
Diagnostic Procedures (AN, DN & WJ Bodies)
1) Using scan tool, read DTCs. On AN and DN bodies, go to
next step. On WJ body, if DTC SPECIFIC GOOD TRIPS counter is not
displayed or displayed count is not "0", go to step 8). If DTC
SPECIFIC GOOD TRIPS counter is displayed and displayed count is "0",

go to next step.
2) Using scan tool, read PARK/NEUTRAL SWITCH input state.
Monitor scan tool while moving gear selector from Park to Reverse. If
PARK/NEUTRAL SWITCH state goes from P/N to D/R, go to next step. If
PARK/NEUTRAL SWITCH state does not go from P/N to D/R, go to step 4).
3) Inspect all related wiring and connectors. Repair as
necessary. If wiring is okay, see INACTIVE DTC CONDITION under SELF-
DIAGNOSTIC SYSTEM. Testing is complete.
4) Turn ignition off. Disconnect PCM harness connectors.
Inspect connector and terminals for damage. Repair as necessary. If
connector and terminals are okay, measure resistance between ground
and Park Neutral Position (PNP) switch sense circuit at Black PCM
harness connector C1 while moving gear selector from Park to Reverse
and back to Park. If resistance changes from less than 10 ohms to
greater than 10 ohms, replace PCM. If resistance does not change as
specified, go to next step.
5) If resistance is less than 10 ohms at all times, go to
next step. If resistance is not as specified, go to step 7).
6) Disconnect PNP switch harness connector. Measure
resistance between ground and PNP switch sense circuit at PNP switch
harness connector. If resistance is less than 5 ohms, repair PNP
switch sense circuit for a short to ground. If resistance is not as
specified, replace PNP switch.
7) Disconnect PNP switch harness connector. Measure
resistance of PNP switch sense circuit between Black PCM harness
connector C1 and PNP switch harness connector. If resistance is less
than 5 ohms, replace PNP switch. If resistance is not as specified,
repair open in PNP switch sense circuit.
8) Conditions required to set DTC P1899 are not present at
this time. DTC P1899 sets if PCM detects an incorrect Park Neutral
Position (PNP) switch state for a given mode of vehicle operation.
Possible causes are: faulty connections, faulty PNP switch, mechanical
transmission problem or PCM failure. Inspect all related wiring and
connectors. Repair as necessary. If wiring is okay, see INACTIVE DTC
CONDITION under SELF-DIAGNOSTIC SYSTEM. Testing is complete.
Diagnostic Procedures (AB & BR Bodies)
1) Using scan tool, read DTCs. If DTC SPECIFIC GOOD TRIPS
counter is not displayed or displayed count is not "0", go to step 7).
If DTC SPECIFIC GOOD TRIPS counter is displayed and displayed count is
"0", go to next step.
2) Using scan tool, check and record FREEZE FRAME data. Use
FREEZE FRAME data to determine conditions when DTC P1899 was set. Turn
ignition on. Using scan tool, read PARK/NEUTRAL SWITCH input state.
Monitor scan tool while moving gear selector from Park to Reverse. If
PARK/NEUTRAL SWITCH state goes from P/N to D/R, go to step 7). If
PARK/NEUTRAL SWITCH state does not go from P/N to D/R, go to next
step.
3) Turn ignition off. Disconnect PCM harness connectors.
Inspect connector and terminals for damage. Repair as necessary. If
connector and terminals are okay, measure resistance between ground
and Park Neutral Position (PNP) switch sense circuit at Black PCM
harness connector C1 while moving gear selector from Park to Reverse
and back to Park. If resistance changes from less than 10 ohms to
greater than 10 ohms, replace PCM. If resistance does not change as
specified, go to next step.
4) If resistance is less than 10 ohms at all times, go to
next step. If resistance is not as specified, go to step 6).
5) Disconnect PNP switch harness connector. Measure
resistance between ground and PNP switch sense circuit at PNP switch
harness connector. If resistance is less than 5 ohms, repair PNP
switch sense circuit for a short to ground. If resistance is not as
specified, replace PNP switch.

5) If PCM has not been replaced, and TEST VER-2A is being
performed after an A/C relay control circuit DTC test, ensure A/C is
on and go to next step.
6) Road test vehicle for at least 5 minutes. Road test
vehicle at a speed of at least 40 MPH at some point during road test.
Stop vehicle. Turn engine off for at least 10 seconds. Start engine
and continue road test. Ensure transmission shifts through all gears.
After road test, turn engine off and go to next step.
7) Using scan tool, read DTCs. If any DTC returns, perform
appropriate test(s). If no DTCs return, test is complete. Go to next
step.
8) Turn ignition on, with engine off. Using scan tool, erase
DTCs. Turn ignition off. Disconnect scan tool. Test is complete.
TEST VER-2A (DIESEL)
NOTE: If Accelerator Pedal Position Sensor (APPS), battery, Engine
Control Module (ECM) or Powertrain Control Module (PCM) has\
been disconnected or replaced, APPS must be reprogrammed and
correct vehicle mileage and Vehicle Identification Number
(VIN) must be programmed into PCM to prevent Diagnostic
Trouble Codes (DTCs) from being set in Anti-Lock Brake System\
(ABS) module and Supplemental Restraint System (SRS) module\
.
To program PCM and clear DTCs from ABS and SRS modules,
proceed to appropriate procedure listed below. On models
equipped with a Smart Key Immobilizer Module (SKIM), if
replacing Powertrain Control Module (PCM), secret key data
must also be updated to enable engine starting. To update
secret key data, proceed to appropriate procedure listed
below.
CAUTION: DO NOT attempt to adjust screws or disassemble APPS. Settings
are preset at factory and are not intended to by changed.
Procedure For Programming APPS
Reassemble all components. Turn ignition switch to ON or RUN
position without starting engine. Slowly press accelerator pedal to
floor once and slowly release. This procedure programs APPS
calibration in ECM. Go to step 1)).
Procedure For Programming PCM & Clearing DTCs From ABS & SRS
Modules
Connect scan tool to Data Link Connector (DLC). Using scan
tool, enter correct VIN and mileage into PCM. Using scan tool
manufacturer's instructions, clear DTCs from ABS and SRS modules. Go
to step 1)).
Procedure For Updating Secret Key Data
Connect scan tool to Data Link Connector (DLC). Go to ENGINE
and then MISC menus on scan tool. Place SKIM in SECURED ACCESS MODE by
using appropriate Personal Identification Number (PIN) for this
vehicle. PIN may be obtained from owner, vehicle's invoice, or from
manufacturer. Select UPDATE THE SECRET KEY DATA. Data will be
transferred from Smart Key Immobilizer Module (SKIM) to PCM. Go to
step 1)).
1) If PCM has not been replaced, and TEST VER-2A (DIESEL) is\
being performed after a No Trouble Code (NTC) test, inspect vehicle to\
ensure all engine components are connected. Reassemble and reconnect
components as necessary. Check if initial symptom still exists. If
initial symptom exists, check for Technical Service Bulletins (TSBs)
that apply to vehicle and see TEST NTC-1A: NO TROUBLE CODE TEST MENU
in ENGINE PERFORMANCE, or appropriate TROUBLE SHOOTING - NO CODES

article in ENGINE PERFORMANCE for diagnosis by symptom. If initial
symptom no longer exists, test is complete. Go to step 6).
2) If PCM has not been replaced, and TEST VER-2A (DIESEL) is\
being performed after a DTC test, inspect vehicle to ensure all engine
components are connected. Reassemble and reconnect components as
necessary. Using scan tool, erase DTCs, reset all memory values and go
to step 4).
3) If PCM has not been replaced, and TEST VER-2A (DIESEL) is\
being performed after an A/C relay control circuit DTC test, ensure
A/C is on and go to next step.
4) Road test vehicle for at least 5 minutes. Road test
vehicle at a speed of at least 40 MPH at some point during road test.
Stop vehicle. Turn engine off for at least 10 seconds. Start engine
and continue road test. Ensure transmission shifts through all gears.
After road test, turn engine off and go to next step.
5) Using scan tool, read DTCs. If any DTC returns, perform
appropriate test(s). If no DTCs return, test is complete. Go to next
step.
6) Turn ignition on, with engine off. Using scan tool, erase
DTCs. Turn ignition off. Disconnect scan tool. Test is complete.
TEST VER-5A (EXCEPT DIESEL)
NOTE: If Powertrain Control Module (PCM) is replaced, correct
vehicle mileage and Vehicle Identification Number (VIN) must
be programmed into PCM to prevent Diagnostic Trouble Codes
(DTCs) from being set in Anti-Lock Brake System (ABS) modul\
e
and Supplemental Restraint System (SRS) module. To program
PCM and clear DTCs from ABS and SRS modules, proceed to
appropriate procedure listed below. On models equipped with a
Smart Key Immobilizer Module (SKIM), if replacing Powertrain
Control Module (PCM), secret key data must also be updated to\
enable engine starting. To update secret key data, proceed to
appropriate procedure listed below.
Procedure For Programming PCM & Clearing DTCs From ABS & SRS
Modules
Connect scan tool to Data Link Connector (DLC). Using scan
tool, enter correct VIN and mileage into PCM. Using scan tool
manufacturer's instructions, clear DTCs from ABS and SRS modules. Go
to step 1)).
Procedure For Updating Secret Key Data
Connect scan tool to Data Link Connector (DLC). Go to ENGINE
and then MISC menus on scan tool. Place SKIM in SECURED ACCESS MODE by
using appropriate Personal Identification Number (PIN) for this
vehicle. PIN may be obtained from owner, vehicle's invoice, or from
manufacturer. Select UPDATE THE SECRET KEY DATA. Data will be
transferred from Smart Key Immobilizer Module (SKIM) to PCM. Go to
step 1)).
1) Inspect vehicle to ensure all engine components are
connected. Reassemble and reconnect components as necessary. If any
DTCs have not been diagnosed, return to appropriate test(s). If all
DTCs have been diagnosed and repaired, go to next step.
2) Connect scan tool to Data Link Connector (DLC) if not
previously done. Ensure fuel tank is at least 1/4 full. Ensure A/C is
off. Go to next step.
3) Proper way to ensure DTC is repaired is to allow
Powertrain Control Module (PCM) to run monitor. Monitor operation may
be observed on scan tool. All specified enabling conditions for
specified DTC must be met before PCM will operate monitor. Go to next
step.

4) Using scan tool, monitor pretest enabling conditions until
all conditions have been met. Once all enabling conditions are met,
observe appropriate monitor for DTC on scan tool. If repaired DTC has
reset or is seen on monitor while on road test, repair is not
complete. Check for related Technical Service Bulletins (TSBs) and
return to appropriate test. If no DTCs return, test is complete. Go to
step 6).
5) If another DTC exists, return to appropriate test(s). If
no DTCs return, test is complete. Go to next step.
6) Turn ignition on, with engine off. Using scan tool, erase
DTCs. Turn ignition off. Disconnect scan tool. Test is complete.
TEST VER-5A (DIESEL)
NOTE: If Accelerator Pedal Position Sensor (APPS), battery, Engine
Control Module (ECM) or Powertrain Control Module (PCM) has\
been disconnected or replaced, APPS must be reprogrammed and
correct vehicle mileage and Vehicle Identification Number
(VIN) must be programmed into PCM to prevent Diagnostic
Trouble Codes (DTCs) from being set in Anti-Lock Brake System\
(ABS) module and Supplemental Restraint System (SRS) module\
.
To program PCM and clear DTCs from ABS and SRS modules,
proceed to appropriate procedure listed below. On models
equipped with a Smart Key Immobilizer Module (SKIM), if
replacing Powertrain Control Module (PCM), secret key data
must also be updated to enable engine starting. To update
secret key data, proceed to appropriate procedure listed
below.
CAUTION: DO NOT attempt to adjust screws or disassemble APPS. Settings
are preset at factory and are not intended to by changed.
Procedure For Programming APPS
Reassemble all components. Turn ignition switch to ON or RUN
position without starting engine. Slowly press accelerator pedal to
floor once and slowly release. This procedure programs APPS
calibration in ECM. Go to step 1)).
Procedure For Programming PCM & Clearing DTCs From ABS & SRS
Modules
Connect scan tool to Data Link Connector (DLC). Using scan
tool, enter correct VIN and mileage into PCM. Using scan tool
manufacturer's instructions, clear DTCs from ABS and SRS modules. Go
to step 1)).
Procedure For Updating Secret Key Data
Connect scan tool to Data Link Connector (DLC). Go to ENGINE
and then MISC menus on scan tool. Place SKIM in SECURED ACCESS MODE by
using appropriate Personal Identification Number (PIN) for this
vehicle. PIN may be obtained from owner, vehicle's invoice, or from
manufacturer. Select UPDATE THE SECRET KEY DATA. Data will be
transferred from Smart Key Immobilizer Module (SKIM) to PCM. Go to
step 1)).
1) If PCM has not been replaced, inspect vehicle to ensure
all engine components are connected. Reassemble and reconnect
components as necessary. If any DTCs have not been diagnosed, return
to appropriate test(s). If all DTCs have been diagnosed and repaired,
go to next step.
2) Ensure fuel tank is at least 1/4 full. Ensure A/C is off.
Proper way to ensure DTC is repaired is to connect scan tool to Data
Link Connector (DLC) and allow Powertrain Control Module (PCM) to ru\
n
a DTC SPECIFIC GOOD TRIP COUNTER for 2 minutes. If DTC SPECIFIC GOOD

13) On A/T models, ensure all electrical connectors are clean
and properly connected to electrical plugs on transmission case. On
all models, check for loose or defective electrical connections on
starter and starter solenoid.
MECHANICAL INSPECTION
Compression
Manufacturer does not provide information for checking
compression.
FUEL SYSTEM
AIR IN FUEL SYSTEM
NOTE: Air in the fuel system may cause hard starting, rough
running, excessive smoke, poor engine performance, engine
misfire, poor fuel economy and fuel knock. Air may enter fuel
system whenever fuel supply lines, fuel filter/water
separator, fuel injection pump, fuel injectors or high
-pressure fuel lines are removed or disconnected.
1) Inspect all low-pressure fuel lines from fuel tank to fuel
transfer pump, fuel heater and fuel filter/water separator for signs
of leakage. Inspect all high-pressure fuel lines for signs of leakage.
See FUEL INJECTOR & HIGH-PRESSURE FUEL LINES under FUEL SYSTEM.
2) After repairing fuel leak, bleed air from fuel system. See
FUEL LINE BLEEDING under FUEL SYSTEM in REMOVAL, OVERHAUL &
INSTALLATION - TRUCKS - DIESEL article.
FUEL HEATER
1) Fuel heater is located in fuel filter/water separator. See
Fig. 1 . Fuel heater uses a fuel heater temperature sensor for
controlling operation of the fuel heater.
2) A defective fuel heater may cause excessive wax build-up
in the fuel filter/water separator during cold ambient temperatures.
Wax build-up may cause hard starting, prevent engine from
accelerating, low power, Blue smoke or White smoke. For testing of
fuel heater and fuel heater temperature sensor, see SYSTEM & COMPONENT
TESTING - TRUCKS - DIESEL article.
FUEL HEATER RELAY
Ensure fuel heater relay, located in power distribution
center is installed correctly and that terminals are not corroded. For
fuel heater relay testing, see SYSTEM & COMPONENT TESTING - TRUCKS -
DIESEL article.
FUEL FILTER/WATER SEPARATOR
NOTE: A blocked or restricted fuel filter/water separator may cause
starting problems, prevent engine from accelerating, low
power or White smoke. If an excessive amount of water
collects in filter/separator in a short period of time, it
may be necessary to drain and clean fuel tank.
1) When ignition switch is first turned to ON position,
WATER-IN-FUEL (WIF) warning light should come on for 2 seconds to
perform bulb and wiring circuit test and then go off. WATER-IN-FUEL
(WIF) warning light is located on instrument panel, just below the

outlet port. See Fig. 7. Start engine. Outlet pressure should not be
more 5 psi (0.4 kg/cm) less than inlet pressure. If pressure drop is
more than 5 psi (0.4 kg/cm), replace fuel filter and retest pressure.
If pressure drop is less than 5 psi (0.4 kg/cm), check for fuel
supply restriction.
NOTE: Due to very small vacuum specifications, use a scan tool and
Periphal Expansion Port (PEP) module with 0-15 psi transducer\
to perform following test.
Fuel Supply Restriction Test
Ensure transfer pump pressure is okay. Disconnect fuel supply
line at fuel transfer pump inlet. Remove plastic clip from pump inlet
and install in end of fuel supply line. Install 3/8" Adapter Hose
(6631) between fuel supply line and pump inlet. Install transducer
from PEP module to "T" fitting on adapter. Connect scan tool to
module. Start engine. Check vacuum reading with engine at full
throttle with no load. If vacuum reading is less than 6 in. Hg, check
for fuel supply air leaks. If vacuum reading is 6 in. Hg or more,
check fuel line for damage, dents and kinks. Repair as necessary. If
no problem is found, remove fuel module from fuel tank and check for
obstructions. Repair as necessary.
NOTE: A 3' section of 1/4" I.D. clear tubing and a 1/8" NPT fitting
are required for the following test.
Fuel Supply Air Leak Test
Clean area around filter inlet fitting plug, then remove
plug. See Fig. 7. Install 1/8" NPT fitting with 1/4" nipple fitting in
test port. Attach clear hose with a clamp to fitting. Place other end
of hose in a fuel container. Turn ignition switch to START position,
then release to RUN position without starting engine. Fuel transfer
pump should run for 25 seconds. After hose has been purged, watch for
any air bubbles in hose. If no bubbles exist, system is okay. If
bubbles exist, check fuel line, fittings and fuel module in tank.
Repair as necessary.
OVERFLOW VALVE
1) Fuel transfer pump delivers more fuel to fuel injection
pump than needed. Surplus fuel is routed back to fuel tank by overflow
valve. Overflow valve is used to secure fuel return line to side of
fuel injection pump. See Fig. 1. A sticking check valve in the
overflow valve may result in low power. Pressure release is set at 14
psi. (1.0 kg/cm
). If outlet valve is stuck closed, a FTC may set.
2) Clean area around outlet valve and fuel return line.
Remove valve from pump and fitting. Using regulated air pressure, test
valve by blowing into valve inlet. Valve should open at 14-16 psi. (1.
0-1.1 kg/cm
). If valve does not open, replace valve. Reduce air
pressure to 10 psi. (0.7 kg/cm). Valve should close. If valve does
not close, replace valve. Using NEW gaskets, install valve through
banjo fitting into fuel injection pump. Tighten valve to 24 ft. lbs.
(30 N.m).
FUEL INJECTOR & HIGH-PRESSURE FUEL LINES
WARNING: DO NOT allow diesel fuel to contact hot engine when checking
fuel injector, as high exhaust temperatures could cause fire.
Use care when working around high-pressure fuel lines, as
fuel is under extreme pressure and could penetrate skin,
causing personal injury. Wear safety goggles and protective
clothing when checking fuel injectors.


F - B ASIC T E STIN G - R W D - G ASO LIN E

1999 D odge P ic ku p R 1500
1999 ENGINE PERFORMANCE
CHRY - Basic Diagnostic Procedures Trucks & RWD Vans
Dakota, Durango, Ram Pickup, Ram Van, Ram Wagon
CAUTION: When battery is disconnected, vehicle computer and memory
systems may lose memory data. Driveability problems may exist
until computer systems have completed a relearn cycle. See
COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION
before disconnecting battery.
INTRODUCTION
The following diagnostic steps will help prevent overlooking
a simple problem. This is also where to begin diagnosis for a no-start
condition.
The first step in diagnosing any driveability problem is
verifying the customer's complaint with a test drive under the
conditions the problem reportedly occurred.
Before entering self-diagnostics, perform a careful and
complete visual inspection. Most engine control problems result from
mechanical breakdowns, poor electrical connections or
damaged/misrouted vacuum hoses. Before condemning the computerized
system, perform each test listed in this article.
NOTE: Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM)\
with a minimum 10-megohm input impedance, unless stated
otherwise in test procedure.
PRELIMINARY INSPECTION & ADJUSTMENTS
VISUAL INSPECTION
Visually inspect all electrical wiring, looking for chafed,
stretched, cut or pinched wiring. Ensure electrical connectors fit
tightly and are not corroded. Ensure vacuum hoses are properly routed
and are not pinched or cut. Inspect air induction system for possible
vacuum leaks.
MECHANICAL INSPECTION
Compression
Ensure battery is fully charged. Warm engine to normal
operating temperature. Disconnect wire at ignition coil to prevent
engine from starting. Check engine compression with all spark plugs
removed and throttle wide open.
Check engine mechanical condition with a compression gauge,
vacuum gauge, or an engine analyzer. See engine analyzer manual for
specific instructions.
COMPRESSION SPECIFICATIONS









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Application Specification
Compression Ratio
Ram Pickup (8.0L) .......................................... 8.4:1\
All Others ................................................. 9.1:1
Normal Compression Pressure .................................... ( 1)

Minimum Compression Pressure
Dakota
2.5L ........................................................ (1)
3.9L, 5.2L & 5.9L ............................. 100 psi (690 kPa)\
Durango ........................................ 100 psi (690 kPa)\
Ram Pickup ..................................... 100 psi (690 kPa)\
Ram Van Ram Wagon .............................. 100 psi (690 kPa)\
Maximum Variation Between Cylinders ............................ ( 1)
( 1) - Information is not available from manufacturer.









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FUEL SYSTEM
FUEL PRESSURE RELEASE
WARNING: Fuel system is under high pressure. ALWAYS release fuel
pressure before attempting to open system for testing or
component replacement. DO NOT allow fuel to flow onto engine
or electrical parts while testing fuel system components.
Vehicles With Fuel Rail Test Port
1) Loosen fuel tank filler cap. Ensure ignition is off.
Remove protective cap from fuel rail test port.
2) Place one end of Fuel Pressure Release Hose (C-4799-1)
into an approved fuel container. Attach remaining end of hose to fuel
rail test port. Use care, as fuel system may be under pressure. Fuel
pressure will be released from fuel system. Remove hose, reinstall
protective cap, and fuel tank filler cap.
3) Wait 5 seconds. Use care when disconnecting fuel lines, as
some fuel pressure may still exist in fuel lines.
NOTE: One or more DTCs may set when fuel pump relay is removed.
Clear DTCs from PCM after fuel pressure release procedure. To
clear DTCs from PCM, see CLEARING DTCS under SELF-DIAGNOSTIC
SYSTEM in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS
article.
Vehicles Without Fuel Rail Test Port
1) Remove gas cap. Using a non-metallic tool, open flapper
valve in filler neck to relieve pressure. Remove fuel pump relay from
Power Distribution Center (PDC). Relays are identified on label under
PDC cover. Start and run engine until it stalls. Attempt to start
engine. Continue restarting engine until it will no longer run. Turn
ignition off.
CAUTION: DO NOT supply power to fuel injector for more than 4 seconds,
or fuel injector may be damaged.
2) Disconnect any fuel injector connector. Connect a jumper
wire between either fuel injector terminal and positive battery
terminal. Connect another jumper wire to other fuel injector terminal.
Momentarily touch other end of jumper wire to negative battery
terminal.
3) Place a shop towel under fuel line quick-connector at fuel
rail. Use care when disconnecting fuel lines, as some fuel pressure
may still exist in fuel lines. Disconnect fuel line quick-connector.
Reinstall fuel pump relay in PDC. Clear DTCs from PCM. To clear DTCs
from PCM, see CLEARING DTCS under SELF-DIAGNOSTIC SYSTEM in SELF-
DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
FUEL PRESSURE TEST