check engine DODGE RAM SRT-10 2006 Service Repair Manual
Page 5081 of 5267
6. Install the clutch plate (4) onto the front of the A/C
compressor (5).
7. Install the compressor shaft bolt (3). Tighten the
bolt to 19 Nꞏm (168 in. lbs.).
NOTE: The shims may compress after tightening
the shaft bolt. Check the air gap in four or more
places to verify the air gap is correct. Spin the pul-
ley before performing a final check of the air gap.
NOTE: On models with the clutch plate recessed
intothepulley,usea90°wiregapgaugetomea-
sure the clutch air gap. On other models, use a
blade type feeler gauge to measure the air gap.
8. With the clutch plate assembled tight against the
shim(s), measure the air gap between the clutch
plate and the pulley and bearing assembly. The air
gap should be between 0.35 - 0.60 mm (0.014 -
0.024 in.). If the air gap is not between specifica-
tions, add or subtract shims as needed until the
correct air gap is obtained.
CAUTION: Be certain that the compressor clutch field coil wire harness is properly routed so that it is not
pinched between the A/C compressor and the field coil connector bracket.
9. Carefully route the compressor clutch field coil wire lead behind the connector bracket (2).
10. Install the compressor clutch fieldcoil connector (1) onto the connector bracket.
11. Position the A/C compressor to the engine and install the retaining bolts (Refer to 24 - HEATING & AIR CON-
DITIONING/PLUMBING/COMPRESSOR-A/C - INSTALLATION).
12. Connect the engine wire harness to the compressor clutch field coil connector.
13. Install the accessory drive belt (Refer to 7 - COOLING/ACCESSORY DRIVE/BELTS-DRIVE - INSTALLATION).
14. Reconnect the negative battery cable.
VISTEON A/C COMPRESSOR
1. Position the A/C clutch field coil (1) squarely onto
the front of the A/C compressor (2).
CAUTION: Position the A/C clutch field coil so that
the coil positioning tabs and the wire harness lead
are oriented in the correct direction. Failure to cor-
rectly position the fieldcoil on the A/C compres-
sor will result in field coil damage.
2. Align the field coil positioning tabs to the recessed
area at the front of the A/C compressor and install
the clutch field coil onto the compressor using a
two jaw puller (3), compressor field coil installer
(Special Tool 9352 in Kit 9349) (4) and the com-
pressor field coil installer spacer (Special Tool 9353
in Kit 9349) (5).
Page 5083 of 5267
7. Verify that there is adequate clearance for the
clutch field coil wire lead and connector (4)
between the compressor housing and the pulley.
NOTE: When installing an original or a new clutch
assembly, try the original shims first. When install-
ing a clutch onto a compressor that previously did
not have a clutch, use the 1.0, 0.50 and 0.13 milli-
meter (0.040, 0.020 and 0.005 inch) shims from the
clutch hardware package which is provided with
the new clutch.
8. Install the clutch shims onto the compressor shaft.
9. Using compressor clutch holding fixture (Special
Tool 9351 in Kit 9349) (1), install the bolt (2) that
secures the clutch plate (3) to the A/C compressor
(5). Hold the clutch plate stationary with the holding
fixture and tighten the bolt to 15 Nꞏm (133 in. lbs.).
10. Using a feeler gauge (1), check the air gap
between the clutch plate (2) and the pulley and
bearing assembly (3). If the air gap is not 0.35 to
0.75 millimeter (0.014 to 0.030 inch), add or sub-
tract shims as required.
11. Position the A/C compressor (4) onto the mount-
ing bracket.
12. Install the bolts that secure the A/C compressor to
themountingbracket.Tightentheboltsto23Nꞏm
(17 ft. lbs.).
13. Connect the engine wire harness to the compres-
sor clutch field coil connector (5).
14. Lower the vehicle.
15. Install the accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
INSTALLATION).
16. Reconnect the negative battery cable.
17. Perform the Clutch Break-in Procedure (Refer to
24 - HEATING & AIR CONDITIONING/CONTROLS/A/C COMPRESSOR CLUTCH - STANDARD PROCE-
DURE).
Page 5137 of 5267
DIAGNOSIS AND TESTING
A/C COMPRESSOR
When investigating an A/C system related noise, you must first know the conditions under which the noise occurs.
These conditions include: weather, vehicle speed, transmission in gear or neutral, engine speed, engine tempera-
ture, and any other special conditions. Noises that develop during A/C operation can often be misleading. For exam-
ple: What sounds like a failed front engine bearing or connecting rod, may be caused by loose bolts, nuts, mounting
brackets or a loose compressor clutch assembly.
Drive belts are speed sensitive. At different engine speeds and dependingupon drive belt tension, drive belts can
develop noises that are mistaken for an A/C compressor noise. Improper drive belt tension can cause a misleading
noise when the compressor clutch is engaged, which may not occur when the compressor clutch is disengaged.
Check the accessory drive belt condition and tension as described in Cooling before beginning this procedure.
1. Select a quiet area for testing. Duplicate the complaint conditions as much as possible. Turn the A/C compressor
On and Off several times to clearly identify the compressor noise. Listen to the A/C compressor while the clutch
is engaged and disengaged. Probe the A/C compressor with an engine stethoscope or a long screwdriver with
the handle held to your ear to better localize the source of the noise.
2. Loosen all of the compressor mounting hardware and retighten. Check thecompressor clutch retainer. Be certain
that the clutch field coil is mounted securely to the A/C compressor, and that the clutch plate and pulley are
properly aligned and have the correct air gap (Refer to 24 - HEATING & AIR CONDITIONING/CONTROLS/
CLUTCH-A/C COMPRESSOR - INSTALLATION).
3. To duplicate high-ambient temperature conditions (high head pressure), restrict the air flow through the A/C con-
denser. Install a manifold gauge set or a scan tool to be certain that the discharge pressure does not exceed
2760 kPa (400 psi).
4. Check the refrigerant system plumbing for incorrect routing, rubbing or interference, which can cause unusual
noises. Also check the refrigerant lines and hoses for kinks or sharp bendsthat will restrict refrigerant flow, which
can cause noises (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - DESCRIPTION - REFRIGER-
ANT LINES).
5. If the noise is from opening and closing of the high pressure relief valve, recover, evacuate and recharge the
refrigerant system (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD PROCEDURE -
REFRIGERANT SYSTEM RECOVERY), (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STAN-
DARD PROCEDURE - REFRIGERANT SYSTEM EVACUATE) and (Refer to 24 - HEATING & AIR CONDITION-
ING/PLUMBING - STANDARD PROCEDURE - REFRIGERANT SYSTEM CHARGE). If the high pressure relief
valve still does not seat properly, replace the A/C compressor (Refer to 24- HEATING & AIR CONDITIONING/
PLUMBING/COMPRESSOR-A/C - REMOVAL).
6. If the noise is from liquid refrigerant slugging in the A/C suction line,replace the A/C accumulator (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING/ACCUMULATOR-A/C - REMOVAL) and check the refrigerant oil
level and the refrigerant system charge (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING/REFRIG-
ERANT OIL - STANDARD PROCEDURE - REFRIGERANT OIL LEVEL) (Refer to 24 - HEATING & AIR CON-
DITIONING/PLUMBING- STANDARD PROCEDURE - REFRIGERANT SYSTEM CHARGE).
7. If a slugging condition still exists after replacing the A/C accumulator, then replace the A/C compressor (Refer to
24 - HEATING & AIR CONDITIONING/PLUMBING/COMPRESSOR-A/C - REMOVAL) and repeat Step 1.
REMOVAL
3.7L/4.7L ENGINES
WARNING: Refer to the applicable warnings and cautions for this system before performing the following
operation (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - WARNINGS) and (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - CAUTIONS). Failure to follow the warnings and cautions could result
in possible personal injury or death.
NOTE: The A/C compressor may be removed and repositioned without disconnecting the refrigerant lines or
discharging the refrigerant system. Discharging is not necessary if servicing the compressor clutch, clutch
coil, engine, engine cylinder head or the generator.
Page 5141 of 5267
1. Recover the refrigerant from the refrigerant system
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - STANDARD PROCEDURE -
REFRIGERANT SYSTEM RECOVERY).
2. Disconnect and isolate the negative battery cable.
3. Remove the accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/BELTS-DRIVE -
REMOVAL).
4. Disconnect the wire harness connector from the
A/C compressor clutch coil connector (4).
5. Remove the bolts (5) that secure the A/C suction
line (1) and the A/C discharge line (3) to the A/C
compressor (2).
6. Disconnect the refrigerant lines from the A/C com-
pressor and remove and discard the seals.
7. Install plugs in, or tape over all of the opened
refrigerant line fittings and the compressor ports.
8. Remove the four bolts (1) that secure the A/C com-
pressor (2) to the cylinder block (3).
9. Remove the A/C compressor from the engine
compartment.
INSTALLATION
3.7L/4.7L ENGINES
NOTE: If a replacement A/C compressor is being installed, be certain to check the refrigerant oil level. See
Refrigerant Oil Level in this group for the procedures. Use only refrigerant oil of the type recommended for
the compressor in the vehicle.
Page 5142 of 5267
1. Position the A/C compressor (2) onto the accessory
mounting bracket (4).
2. Install and tighten the bolts in the following
sequence:
Install bolt (3) and hand tighten.
Install bolt (6) and hand tighten.
Install bolt (1) and hand tighten.
Tightened bolt (3) to 40 Nꞏm (30 ft. lbs.).
Tightened bolt (6) to 55 Nꞏm (41 ft. lbs.).
Tightened bolt (1) to 55 Nꞏm (41 ft. lbs.).
Tightened bolt (5) to 55 Nꞏm (41 ft. lbs.).
3. Remove the tape or plugs from the opened refrig-
erant line fittings and the compressor ports.
4. Lubricate new seals with clean refrigerant oil and
install them onto the refrigerant line fittings. Use
only the specified seals as they are made of a spe-
cial material for the R-134a system. Use only
refrigerant oil of the type recommended for the A/C
compressor in the vehicle.
5. Install the A/C suction line (5) and the A/C dis-
charge line (9) onto the A/C compressor (6).
6. Install the nuts (4) that secure the refrigerant lines
to the A/C compressor. Tighten the nuts to 20 Nꞏm
(15 ft. lbs.).
7. Install the accessory drive belt (Refer to 7 - COOL-
ING/ACCESSORY DRIVE/BELTS-DRIVE - INSTAL-
LATION).
8. Reconnect the negative battery cable.
9. Evacuate the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE).
10. Charge the refrigerant system (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD PRO-
CEDURE - REFRIGERANT SYSTEM CHARGE).
5.7L ENGINE
NOTE: Be certain to check the refrigerant oil level if the A/C compressor isbeing replaced. See Refrigerant
Oil Level in this group for the procedures. Use only refrigerant oil of the type recommended for the A/C
compressor in the vehicle.
Page 5143 of 5267
1. Position the A/C compressor (2) into the engine
compartment.
2. Install and tighten the bolts that secure the A/C
compressor to the mounting bracket (4) in the fol-
lowing sequence:
Install the two lower bolts (1) and hand tighten.
Install the rear bolt (3) and hand tighten.
Tightenthetwolowerboltsto40Nꞏm(30ft.
lbs.).
Tighten the rear bolt to 55 Nꞏm (41 ft. lbs.).
3. Install the generator support bracket (Refer to 8 -
ELECTRICAL/CHARGING/GENERATOR -
INSTALLATION).
4. Remove the tape or plugs from the opened refrig-
erant line fittings and the compressor ports.
5. Lubricate new O-rings and dual plane seals with
clean refrigerant oil and install them onto the refrig-
erant line fittings. Use only the specified seals as
they are made of a special material for the R-134a
system. Use only refrigerant oil of the type recom-
mended for the A/C compressor in the vehicle.
6. Install the A/C discharge line (1) and the A/C suc-
tion line (5) onto the A/C compressor (6).
7. Install the nuts (4 and 7) that secure the refrigerant
lines to the A/C compressor. Tighten the nuts to 20
Nꞏm (15 ft. lbs.).
8. Connect the wire harness connector to the clutch
field coil connector and the A/C pressure trans-
ducer (8).
9. Install the accessory drive belt (Refer to 7 - COOL-
ING/ACCESSORY DRIVE/BELTS-DRIVE - INSTAL-
LATION).
10. Reconnect the negative battery cable.
11. Evacuate the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING - STANDARD PROCEDURE - REFRIGERANT SYSTEM EVAC-
UATE).
12. Charge the refrigerant system (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD PRO-
CEDURE - REFRIGERANT SYSTEM CHARGE).
5.9L DIESEL ENGINE
NOTE: Be certain to check the refrigerant oil level if the A/C compressor isbeing replaced. See Refrigerant
Oil Level in this group for the procedures. Use only refrigerant oil of the type recommended for the A/C
compressor in the vehicle.
Page 5144 of 5267
1. Position the A/C compressor (2) onto the mounting
bracket (3) located on the right side of the cylinder
block (4).
2. Install and hand tighten the four bolts (1) that
secure the A/C compressor to the mounting
bracket.
3. Tighten the bolts that secure the A/C compressor to
themountingbracketto23Nꞏm(17ft.lbs.).
4. Remove the tape or plugs from the opened refrig-
erant line fittings and the compressor ports.
5. Lubricate new seals with clean refrigerant oil and
install them onto the refrigerant line fittings. Use
only the specified seals as they are made of a spe-
cial material for the R-134a system. Use only
refrigerant oil of the type recommended for the A/C
compressor in the vehicle.
6. Install the A/C suction and discharge line assembly
(2) onto the A/C compressor (3).
7. Install the bolt (1) that secures the refrigerant line
assembly to the A/C compressor. Tighten the bolt
to 23 Nꞏm (17 ft. lbs.).
8. Connect the wire harness to the clutch field coil
wire lead connector (4).
9. Install the accessory drive belt (Refer to 7 - COOL-
ING/ACCESSORY DRIVE/BELTS-DRIVE - INSTAL-
LATION).
10. Reconnect the negative battery cable.
11. Evacuate the refrigerant system (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD
PROCEDURE - REFRIGERANT SYSTEM EVACUATE).
12. Charge the refrigerant system (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD PRO-
CEDURE - REFRIGERANT SYSTEM CHARGE).
8.3L ENGINE
NOTE: Be certain to check the refrigerant oil level if the A/C compressor isbeing replaced. See Refrigerant
Oil Level in this group for the procedures. Use only refrigerant oil of the type recommended for the A/C
compressor in the vehicle.
Page 5188 of 5267
OIL-A/C REFRIGERANT
DESCRIPTION
The refrigerant oil used in R-134a refrigerant systems is a synthetic-based, polyalkylene glycol (PAG), wax-free
lubricant. Mineral-based R-12 refrigerant oils are not compatible with PAG oils, and should never be introduced to
an R-134a refrigerant system.
There are different PAG oils available, and each contains a different additive package. Useonlyrefrigerant oil of the
same type as recommended to service the refrigerant system (always refer to the specification tagincluded with
the replacement A/C compressor or the A/C Underhood Specification Label located in the engine compartment).
The Denso 10S17 A/C compressor used in this vehicle when equipped with the 3.7L, 4.7L, 5.7L or 8.3L engine is
designed to use ND-8 PAG refrigerant oil. Use only this type of refrigerantoil when servicing the A/C compressor for
these engines.
The Visteon HS-18 A/C compressor used in this vehicle when equipped with 5.9L diesel engine is designed to use
VC-46 PAG refrigerant oil. Use only this type of refrigerant oil when servicing this A/C compressor.
OPERATION
After performing any refrigerant recovery or recycling operation, always replenish the refrigerant system with the
same amount of the recommended refrigerant oil as was removed. Too little refrigerant oil can cause A/C compres-
sor damage, and too much can reduce A/C system performance.
PAG refrigerant oil is more hygroscopic than mineral oil, and will absorb any moisture it comes into contact with,
even moisture in the air. The PAG oil container should always be kept tightly capped until it is ready to be used.
After use, recap the oil container immediately to prevent moisture contamination.
STANDARD PROCEDURE
REFRIGERANT OIL LEVEL
When an A/C system is assembled at the factory, all components except the A/C compressor are refrigerant oil free.
After the refrigerant system has been charged and operated, the refrigerant oil in the A/C compressor is dispersed
throughout the refrigerant system. The accumulator, A/C evaporator, A/Ccondenser and the A/C compressor will
each retain a significant amount of the needed refrigerant oil.
It is important to have the correct amount of refrigerant oil in the A/C system. This ensures proper lubrication of the
A/C compressor. Too little oil will result in damage to the A/C compressor,while too much oil will reduce the cooling
capacity of the A/C system and consequently result in higher discharge airtemperatures.
CAUTION: The refrigerant oil in the R-134a A/C system is unique depending on the A/C compressor used.
Use only PAG oils that are designed to work with R-134a refrigerant and the A/C compressor in the vehicle.
Always refer to the A/C Underhood Specification Label for the correct oil designation. The oil container
should be kept tightly capped until it is ready for use and then tightly capped after use to prevent contam-
ination from dirt and moisture. Refrigerant oil will quickly absorb any moisture it comes in contact with,
therefore, special effort must be used to keep all R-134a system components moisture-free. Moisture in the
refrigerant oil is very difficult toremove and will cause a reliability problem with the A/C compressor.
NOTE: Most reclaim/recycling equipment will measure the lubricant beingremoved during recovery. This
amount of lubricant should be added back into the system. Refer to the reclaim/recycling equipment man-
ufacturers instructions.
It will not be necessary to check the oil level in the A/C compressor or to addoil, unless there has been an oil loss.
An oil loss may occur due to a rupture or leak from a refrigerant line, a connector fitting, a component, or a com-
ponent seal. If a leak occurs, add 30 milliliters (1 fluid ounce) of refrigerant oil to the refrigerant system after the
repair has been made. Refrigerant oil loss will be evident at the leak pointby the presence of a wet, shiny surface
around the leak.
Refrigerant oil must be added when an accumulator, A/C evaporator or A/C condenser is replaced. See the Refrig-
erant Oil Capacities chart. When an A/C compressor is replaced, the refrigerant oil must be drained from the old
Page 5191 of 5267
TUBE-A/C ORIFICE
DESCRIPTION
The fixed A/C orifice tube is installed in the A/C liquid
line and provides a restriction in the liquid refrigerant
line between the A/C condenser and the A/C evapora-
tor. This restriction established the pressure differential
between the high and low-pressure sides of the A/C
system.
The A/C orifice tube includes a diffuser screen (1),
O-ring seals (2) to seal it to the inner wall of the A/C
liquid line, an inlet filter screen (3) and the fixed orifice
(4).
OPERATION
The fixed A/C orifice tube is used to meter the flow of liquid refrigerant into the A/C evaporator. The high-pressure
liquid refrigerant from the A/C condenser expands into a low-pressure liquid as it passes through the metering orifice
and diffuser screen of the A/C orifice tube.
The A/C orifice tube is not serviceable and cannot be repaired and, if faulty or plugged, the A/C liquid line must be
replaced (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING/LINE-A/C LIQUID - DESCRIPTION).
DIAGNOSIS AND TESTING
A/C ORIFICE TUBE
WARNING: The A/C liquid line between the A/C condenser and the A/C orifice tube can become hot enough
to burn the skin. Use extreme caution when performing the following test toprevent possible personal
injury.
NOTE: The A/C orifice tube can be checked for proper operation using the following procedure. However,
the A/C orifice tube is only serviced as a part of the A/C liquid line. If the results of this test indicate that the
A/C orifice tube is obstructed or missing, the A/C liquid line must be replaced.
1. Confirm that the refrigerant system is properly charged (Refer to 24 - HEATING & AIR CONDITIONING - DIAG-
NOSIS AND TESTING - A/C PERFORMANCE).
2. Start the engine. Turn on the A/Csystem and confirm that the compressor clutch is engaged.
3. Allow the A/C system to operate for five minutes.
4. Lightly and cautiously touch the A/C liquid line near the condenser outlet at the front of the engine compartment.
TheA/Cliquidlineshouldbehottothetouch.
5. Touch the A/C liquid line near the evaporator inlet at the rear of the engine compartment. The A/C liquid line
should be cold to the touch.
6. If there is a distinct temperature differential between the two ends of the A/C liquid line, the A/C orifice tube is in
good condition. If there is little or no detectable temperature differential between the two ends of the A/C liquid
line, the A/C orifice tube is obstructed or missing and the A/C liquid line must be replaced (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING/LINE-A/C LIQUID - REMOVAL).
Page 5193 of 5267
EMISSIONS CONTROL
DESCRIPTION
STATE DISPLAY TEST MODE
The switch inputs to the Powertrain Control Module (PCM) have two recognized states; HIGH and LOW. For this
reason, the PCM cannot recognize the difference between a selected switchposition versus an open circuit, a short
circuit, or a defective switch. If the State Display screen shows the changefromHIGHtoLOWorLOWtoHIGH,
assume the entire switch circuit to the PCM functions properly. Connect the DRB scan tool to the data link con-
nector and access the state display screen. Then access either State Display Inputs and Outputs or State Display
Sensors.
CIRCUIT ACTUATION TEST MODE
The Circuit Actuation Test Mode checks for proper operation of output circuits or devices the Powertrain Control
Module (PCM) may not internally recognize. The PCM attempts to activate these outputs and allow an observer to
verify proper operation. Most of the tests provide an audible or visual indication of device operation (click of relay
contacts, fuel spray, etc.). Except for intermittent conditions, if a device functions properly during testing, assume the
device, its associated wiring, and driver circuit work correctly. Connect the DRB scan tool to the data link connector
and access the Actuators screen.
DIAGNOSTIC TROUBLE CODES
A Diagnostic Trouble Code (DTC) indicates the PCM has recognized an abnormal condition in the system.
Remember that DTC’s are the results of a system or circuit failure, but do not directly identify the failed
component or components.
BULB CHECK
Each time the ignition key is turned to the ON position, the malfunction indicator (check engine) lamp on the instru-
ment panel should illuminate for approximately 2 seconds then go out. Thisis done for a bulb check.
OBTAINING DTC’S USING DRB SCAN TOOL
1. Obtain the applicable Powertrain Diagnostic Manual.
2. Obtain the DRB Scan Tool.
3. Connect the DRB Scan Tool to the data link (diagnostic) connector. This connector is located in the passenger
compartment at the lower edge of instrument panel, and near the steering column.
4. Turn the ignition switch on and access the “Read Fault” screen.
5. Record all the DTC’s and “freeze frame” information shown on the DRB scantool.
6. To erase DTC’s, use the “Erase Trouble Code” data screen on the DRB scan tool.Do not erase any DTC’s
until problems have been investigated and repairs have been performed.
TA S K M A N A G E R
The PCM is responsible for efficiently coordinating the operation of all the emissions-related components. The PCM
is also responsible for determining if the diagnostic systems are operating properly. The software designed to carry
out these responsibilities is called the ’Task Manager’.
MONITORED SYSTEMS
There are new electronic circuit monitors that check fuel, emission, engine and ignition performance. These moni-
tors use information from various sensor circuits to indicate the overalloperation of the fuel, engine, ignition and
emission systems and thus the emissions performance of the vehicle.
The fuel, engine, ignition and emission systems monitors do not indicate aspecific component problem. They do
indicate that there is an implied problem within one of the systems and thata specific problem must be diagnosed.
If any of these monitors detect a problem affecting vehicle emissions, theMalfunction Indicator Lamp (MIL) will be
illuminated. These monitors generate Diagnostic Trouble Codes that can be displayed with the MIL or a scan tool.