ignition CHEVROLET DYNASTY 1993 Service Manual

NONÐCOMPUTER AIDED DIAGNOSTIC TESTS
Determine whether the operator complaint is due
to a system failure or improper operation of the ATC
system. The system will to go into a maximum heat
or cooling mode if the operator changes the tempera-
ture setting four or more degrees. Check the following:
² Coolant level
² Refrigerant charge
² Drive belt tension
² Radiator air flow
² Radiator fan operation
² Air suction of In-car Temperature Sensor/Aspirator
To check air suction of the Aspirator, place a small
piece of tissue paper over the Aspirator opening on
the instrument panel. This opening is located to the
right of the steering column. The tissue paper should
cling to the opening if system is functioning properly. Bring the engine to normal operating temperature
and proceed with Computer Aided Diagnostic Proce-
dures. Always test the entire system after each re-
pair has been performed.
COMPUTER AIDED DIAGNOSTIC TESTS
The ATC control has a computer capable of trou-
bleshooting the entire ATC system in approximately
60 seconds. The engine must be running and at nor-
mal operating temperature during the test to provide
hot coolant for the heater. During the ATC Diagnostic Test, the computer will
calibrate the Mode and Blend Door actuators.
CAUTION: Do not remove the actuators from the
heater-A/C unit assembly with power applied. Re-
moval should only be done with the Ignition OFF.
The actuators have no mechanical stops to limit the
travel. If the actuator rotates and is not connected
to the unit assembly, it will become un-calibrated.
The Diagnostic Test is capable of checking all elec-
trical signals between the ATC Control Module, ac-
tuators, sensors and blower control. The Diagnostic Test will display two types of Diag-
nostic trouble Codes (Fig. 21). The Diagnostic Trou-
ble Codes numbered 01 through 22, have been
detected during the Diagnostic Test. Diagnostic Trou-
ble Codes numbered 23 through 28, have been de-
tected during normal ATC operation. Diagnostic
Trouble Codes 23 through 28 would then be stored in
the ATC control computer and are only being re-
trieved during the Diagnostic Test.
For electrical pin numbers, refer to the wiring Pin
out charts on the following pages in this section. (1) Start vehicle and allow engine to warm up.
(2) For two seconds, depress the DEFROST,
FLOOR and MODE buttons at the same time. The
ATC control should begin to flash on and off. (3) During the Diagnostic Test perform the follow-
ing symptom tests: (a) Do all display symbols and indicators illumi-
nate ?
Fig. 19 Sun Sensor
Fig. 20 Sun Sensor Removal
Fig. 21 Automatic Temperature Control Diagnostic Trouble Codes
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(b) Does the blower motor operate at its highest
speed ? (c) Feel the outlet temperature. Does it get hot
and then cycle cold ? (d) Does the air flow switch from DEFROST out-
lets and then cycle to PANEL outlets?
If you can answer NO to any of these questions,
proceed to step 4, otherwise proceed to step 5. (4) If you answered NO to:
SYMPTOM A
The display symbols and indicators do not illumi-
nate. Diagnostic Trouble Codes are not displayed.
TEST
After self-diagnostic test is complete, select a mode
that will display the malfunction.
ACTION
If the ATC system operates properly, and the dis-
play does not, replace ATC control panel computer.
SYMPTOM B
The blower motor does not operate.
CAUTION: Stay clear of blower motor and power
module (PM) heat sink. Do not run system for more
than 10 minutes with PM removed from A/C unit.
TEST Check all power module and blower motor connec-
tions. Use a voltmeter to test for 12 volts (ignition)
at both ends of the fuse with ignition ON. If fuse is
good, test the green wire at the blower motor connec-
tor for 12 volts (ignition) to body ground. Turn ignition to the ON position.
With the blower motor still connected, check for 12
volts to body ground on the black/tan wire of the
blower motor two way connector. Check for 12 volts at the Power Module pin #4
(BK/TN). Check for continuity from the Power Module pin
#3 (BK) to chassis ground. Replace the Power Module.
ACTION If 12 volts is not detected, repair feed circuit. Refer
to the Front Wheel Drive Car-Wiring Diagrams Ser-
vice Manual. If 12 volts is not detected, repair wires of the
blower motor or replace the blower motor. If 12 volts is not present, repair wire from the
blower motor connector to the Power Module. If circuit is open, repair ground circuit of the Power
Module. Replace the Power Module (power transistor open).
SYMPTOM C
The outlet air temperature does not become hot
and then cycle to cold during self-test operation. Di-
agnostic Trouble Codes are not displayed.
TEST/ACTION
Make sure the blend-air door is properly attached
to the actuator. If cold air is not discharged from the outlets, check
the base A/C refrigerant system. Make sure heating operation works correctly, (wa-
ter level, thermostat, heater hoses, heater core, etc.).
SYMPTOM D
Air does not flow from DEFROST outlets and then
cycle to PANEL outlets during self-test operation.
TEST/ACTION Check linkages from the mode door actuator for
binding. Check for proper door travel in the unit.
(5) The computer will do one of two things:
² Will return to the control settings that were se-
lected before the Diagnostic Test was started. This
means the test is over. If Diagnostic Trouble Codes
did not occur, and answers to questions (a), (b), (c),
and (d) were YES, the entire system is operating cor-
rectly.
² The blower motor will stop and the computer will
flash a Diagnostic Trouble Code number from 01
through 28. Record the number and then depress the
PANEL button to advance to the next test. If the
ATC control flashes one or more codes 23 to 28, the
digits on the display will flash alternating Zeros. If
you do nothing, these codes will remain stored within
the ATC control computer. After all repairs have
been made erase fault codes. Refer to Erasing Diag-
nostic Trouble Codes 23 through 28 from ATC Con-
trol in this section. Repair all Diagnostic Trouble Codes in the order
that they have been indicated, and then retest the
system. If any blend door test fails, all remaining
blend door tests will be skipped. IF any mode door
tests fail, all remaining mode door tests will be
skipped. Diagnostic Test can be stopped at any time by de-
pressing any button other than PANEL.
DIAGNOSTIC TROUBLE CODE DEFINITIONS
Non-computer aided diagnostics should be per-
formed first. Hood of vehicle should be closed during
the diagnostic test to keep engine heat from effecting
the ambient temperature sensor. Also refer to the wiring Pin out charts.
² DIAGNOSTIC TROUBLE CODE 1
Involves the wiring or the ATC control head.
² DIAGNOSTIC TROUBLE CODES 2, 13, 14, 15,
20, and 23
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(4) If pin #13 shows continuity, repair circuit C02
and retest. (5) If no continuity is shown, replace the ATC con-
trol and retest.
DIAGNOSTIC TROUBLE CODE 7ÐBLOWER DRIVE SIGNAL NOT HIGH
First check the 4-way connector to the power
module for correct installation (1) With the ignition ON, check for ignition volt-
age to the power module pin #1 from the ATC con-
trol. If ignition is present at the power module,
proceed to step 3. If not proceed to step 2. (2) With the 21-way connector still connected and
the ignition ON, check for power module ignition
feed at the control pin #12. If ignition is not present,
replace the control. If ignition voltage is present, re-
pair the open in the wire between the control pin
#12 and power module pin #1. Retest system. (3) Turn ignition OFF and disconnect the 21-way
connector. Measure the resistance between pins #2
and #12. The resistance should read between 2,600
and 2,800 ohms. If correct, replace the ATC control.
If not correct, proceed to step 4. (4) Remove the 4-way connector from the power
module. Check for continuity between the ATC con-
trol pin #2 and power module pin #2. If no continu-
ity is shown, repair the wire for an open. If
continuity is shown, replace the power module and
retest.
DIAGNOSTIC TROUBLE CODE 8ÐA/D CONVERTOR INTERNAL FAILURE
Diagnostics will indicate a Diagnostic Trouble Code
8 if the internal reference voltage of the A/D Conver-
tor is not correct. This Diagnostic Trouble Code is
not serviceable. If a Diagnostic Trouble Code 8 oc-
curs, the computer control head must be replaced.
DIAGNOSTIC TROUBLE CODE 9ÐSUN LOAD SENSOR FAILURE
(1) Unplug the 21-way connector from the control
and check pin #19 for continuity to chassis ground.
If continuity is present, repair the wire shorted to
ground. If no continuity is present, proceed to step 2. (2) Plug the 21-way connector back in. Remove pin
#19 from the 21 way connector and run diagnostics
again. If Diagnostic Trouble Code 9 is still present,
replace the control. If code 9 is not present, replace
the sun sensor.
DIAGNOSTIC TROUBLE CODE 10ÐWATER TEMPERATURE SENSOR FAILURE
(1) Disconnect 21-way connector at control. Mea-
sure resistance between pin #17 and pin #7. This
value will change with temperature. Refer to Tem-
perature ReferenceÐDiagnostic Trouble Code 10
chart. (2) Check for continuity between pin #17 and
chassis ground. If continuity is present, repair and
retest.
DIAGNOSTIC TROUBLE CODE 11ÐAMBIENT TEMPERATURE SENSOR FAILURE
(1) Disconnect 21-way connector at control. With
an ohmmeter, measure the resistance between pin
#9 and pin #7. Refer to the Temperature Refer-
enceÐDiagnostic Trouble Code 11 chart.
(2) Check for continuity between pin #9 and chas-
sis ground. If continuity is present, repair and retest.
TEMPERATURE REFERENCEÐDIAGNOSTIC TROUBLE CODE 10
TEMPERATURE REFERENCEÐDIAGNOSTICTROUBLE CODE 11
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DIAGNOSTIC TROUBLE CODE 12ÐIN-CAR TEMPERATURE SENSOR/ASPIRATORFAILURE
(1) Disconnect 21-way connector at control. With
an ohmmeter, measure the resistance between pin
#20 and pin #7. Refer to Temperature Refer-
enceÐDiagnostic Trouble Code 11 chart for electrical
values. (2) Check for continuity between pin #20 and
chassis ground. If continuity is present, repair and
retest.
DIAGNOSTIC TROUBLE CODE 13ÐBLEND DOOR FAILED TO DRIVE TO HEAT POSITION
(1) Check door and linkage for binding.
(2) Disconnect 21-way connector from control head
and the 5-way connector from the blend air door ac-
tuator. Check continuity between pin #6 of the 21-
way connector and pin #5 of the 5-way connector. If
continuity is shown, go to step 3. If continuity is not
shown, repair circuit for an open circuit and retest
system. (3) Plug in the 5-way connector and check for re-
sistance between pins #4 and #6 of the 21-way con-
nector. A resistance of 20-50 ohms should be present.
If not, replace actuator. If correct, proceed to step 4. (4) If steps 1 and 2 indicate no failures, replace the
ATC control head.
DIAGNOSTIC TROUBLE CODE 14ÐBLEND DOOR FAILED TO DRIVE TO COLD POSITION
First check the 5-way connector to the blend
air door actuator for proper connection (1) Check door and linkage for binding.
(2) Remove the 21-way connector from the control.
With ignition ON, check for ignition voltage between
pin #8 of the 21-way connector and chassis ground.
If voltage is present, repair circuit for short to igni-
tion voltage. If voltage is not present, proceed to step
3. (3) Turn ignition OFF. With the 21-way still re-
moved, disconnect the 5-way connector from the
blend air door actuator. Check for continuity between
pin #8 of the 21-way connector and pin #1 of the
5-way connector. If continuity is not present, repair
open circuit. If present, continue to step 4. (4) Install the 5-way connector back into the blend
air door actuator and check for continuity between
the pins #7 and #8 of the 21-way connector. If con-
tinuity is present, replace the ATC control. If conti-
nuity is not present, replace the blend air door
actuator.
DIAGNOSTIC TROUBLE CODE 15ÐBLEND DOOR FEEDBACK SHORTED TO GROUND
(1) Remove the 21-way connector from the control
and the 5-way connector from the blend air door ac-
tuator. (2) Check for continuity between pin #8 of the 21-
way connector and chassis ground. If present, repair
circuit for short to ground. If not present, continue to
step 3. (3) Plug in the 5-way connector and measure resis-
tance between pins #7 and #8 of the 21-way connec-
tor. If the resistance is less than 10 ohms, replace the
actuator. If not, replace the control head.
DIAGNOSTIC TROUBLE CODE 16ÐMODE DOOR MOVED DURING BLEND DOOR TEST
(1) Remove the 21-way connector from the control
and the 5-way connector from the three actuators. (2) Check for continuity between pin #4 of the 21-
way connector and pin #4 of each actuator. If conti-
nuity is not present for a particular actuator circuit,
repair that circuit and retest system. If continuity is
present for all circuits, continue to step 3. (3) Plug in the 5-way connectors and check for re-
sistance between pins #4 and #6 of the 21-way con-
nector for the blend air actuator. Then check pins #4
and #5 of the 21-way for the mode actuator. The re-
sistance should be between 20-50 ohms. If either of
the actuators do not pass the resistance tests, replace
that particular actuator and retest the system. If
both pass the resistance test, replace the ATC con-
trol.
DIAGNOSTIC TROUBLE CODE 17ÐMODE DOOR FAILED TO DRIVE TO DEFROST
(1) Disconnect 21-way connector from control head
and the 5-way connector from the blend air door ac-
tuator. Check continuity between pin #5 of the 21-
way connector and pin #5 of the 5-way connector. If
continuity is present, proceed to step 2. If continuity
is not present, repair open circuit and retest system. (2) Plug in the 5-way connector and check for re-
sistance between pins #4 and #5 of the 21-way con-
nector. A resistance of 20-50 ohms should be present.
If not, replace actuator. If correct, proceed to step 3. (3) If steps 1 and 2 do not indicate any failures, re-
place the ATC control head.
DIAGNOSTIC TROUBLE CODE 18ÐMODE DOOR FAILED TO DRIVE TO PANEL
Check the 5-way connector to the mode door
actuator for proper installation. (1) Check the door and linkage for binding.
(2) Remove the 21-way connector from the control.
With ignition ON, check for ignition voltage between
pin #16 of the 21-way connector and chassis ground.
If voltage is present, repair circuit for short to igni-
tion voltage. If voltage is not present, proceed to step
3. (3) Turn ignition OFF. With the 21-way connector
still removed, disconnect the 5-way connector from
the mode door actuator. Check for continuity be-
tween pin #16 of the 21-way connector, and pin #1
Ä HEATING AND AIR CONDITIONING 24 - 81