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Diagnostic Manual, Climate Control, Volume 1

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LOCATION:    3.1 Air Conditioning (A/C)    >   11 Diagnosis - Diagnostic Trouble Code (DTC) Memory


Diagnosis - Diagnostic Trouble Code (DTC) Memory

Test step display Possible Cause Test Step/Remedy 1)
In - car temperature sensor 23 1.0
Outside temperature sensor 23 2.0
Evaporator temperature sensor 23 3.0
Heater core temperature sensor 23 4.0
ECT sensor 23 5.0
Temperature selector wheel setting (oC) A/C pushbutton control module
Vehicle speed (km/h) DM, Body and Accessories, Vol. 3 - 11.2
Soft top open , soft top closed 23 14.0
System voltage 23 16.0 - 17.0
OFF/ON (not used) -
2) Blower voltage (0.5 V) - (6.0 V) 23 22.0
1) Observe Preparation for Test, see 22 .
2) Starting approximately 11/91.

Test preparations for test modes B. and C.
Turn temperature selector wheel to white field.

Turn ignition " ON " and within 10 seconds press , and simultaneously for 2 to 4 seconds.

The display will show permanent DTC's stored in memory. After each DTC is displayed and recorded, press again until the display reads .

Press once again. Now the stored intermittent DTC's will be displayed. The symbol will appear after each DTC to indicate an intermittent fault. After each DTC is displayed and recorded, press again unttil the dissplay reads .

Press once again. The display will alternately blink the number and the in - car temperature in oC. Press until all temperature sensor display numbers from - are shown (see section C).
Press once again and the display will alternately blink the number and the voltage of the potentiometer for the center air outlet flap dependent upon the setting (open or closed). The voltage, for example, for 3.5 V is displayed as . Press until all potentiometer and feedback potentiometer display numbers from
- are shown. Press until the display reads " " and the symbol blinks.

Turn ignition OFF and repair recorded DTC's.

Note:
The DTC's can be redisplayed as often as desired. To do so, turn ignition OFF and ON and within 10 seconds press , and simultaneously for 2 to 4 seconds and then press only . The light diode inside will blink once per second during the impulse readout.

Erasing DTC's
Turn ignition ON and within 10 seconds press , and simultaneously for 2 to 4 seconds until "- - -" appears on the display.

Verification
Repeat readout of DTC's. The number (no fault) must appear in the display window.


Electrical Wiring Diagrams:
See "Electrical Troubleshooting Manual", Model 129

B. DTC readout with permanent and intermittent faults

Diagnostic Trouble Code (DTC) Possible Cause Test Step/Remedy 1)
No stored DTC's in system memory -
In - car temperature sensor (B10/4), short circuit 23 1.0
In - car temperature sensor (B10/4), open circuit 23 1.0
Outside temperature sensor (B10/5), short circuit 23 2.0
Outside temperature sensor (B10/5), open circuit 23 2.0
Evaporator temperature sensor (B10/6), short circuit 23 3.0
Evaporator temperature sensor (B10/6), open circuit 23 3.0
Heater core temperature sensor (B10/1), short circuit 23 4.0
Heater core temperature sensor (B10/1), open circuit 23 4.0
ECT sensor (B10/8), short circuit 23 5.0
ECT sensor (B10/8), open circuit 23 5.0
Center air outlet adjuster (N18/2r2), short circuit 23 7.0
Center air outlet adjuster (N18/2r2), open circuit 23 7.0
Center air outlet feedback potentiometer (R23/3), short circuit 23 12.0
Center air outlet feedback potentiometer (R23/3), open circuit 23 12.0
Left air outlet adjuster (N18/2r1), short circuit 23 6.0
Left air outlet adjuster (N18/2r1), open circuit 23 6.0
Left air outlet feedback potentiometer (R23/1), short circuit 23 11.0
Left air outlet feedback potentiometer (R23/1), open circuit 23 11.0
Right air outlet adjuster (N18/2r3), short circuit 23 8.0
Right air outlet adjuster (N18/2r3), open circuit 23 8.0
Right air outlet feedback potentiometer (R23/2), short circuit 23 13.0
Right air outlet feedback potentiometer (R23/2), open circuit 23 13.0
Auxiliary coolant pump (M13), short circuit 23 20.0
Automatic A/C monovalve (Y19), short circuit 23 19.0
A/C compressor signal, short circuit 23 25.0
Auxiliary fan signal, 2nd stage, short circuit 23 24.0
Auxiliary fan signal, 1st stage, short circuit 23 23.0
Not used -
Switchover valve block (Y11), short circuit 23 21.0
Auxiliary coolant pump (M13), open circuit 23 20.0
Automatic A/C monovalve (Y19), open circuit 23 15.0
A/C compressor signal, open circuit 23 25.0
Auxiliary fan signal, 2nd stage, open circuit 23 24.0
Auxiliary fan signal, 1st stage, open circuit 23 23.0
1) Observe Preparation for Test, see 22 .

C. Readout of momentary sensor temperatures as well as potentiometer and feedback potentiometer voltages.

Test step Test scope Test connection Nominal value Test step/Remedy
In - car temperature sensor Press Indicated value may deviate by no more than ± 1 oC 23 1.0
Outside temperature sensor Press Indicated value may deviate by no more than ± 3 oC 23 2.0
Evaporator temperature sensor Press Indicated value may deviate by no more than ± 3 oC 23 3.0
Heater core temperature sensor Press Indicated value may deviate by no more than ± 3 oC 23 4.0
ECT sensor Press Indicated value may deviate by no more than ± 3 oC 23 6.0
Center air outlet adjuster Move center air outlet adjuster completely to the right (outlet closed)

Move center air outlet adjuster completely to the left (outlet open)
- 0.6 - 0.9 V



- 3.9 - 4.5 V
23 8.0
Center air outlet feedback potentiometer Move center air outlet adjuster completely to the right (outlet closed)

Move center air outlet adjuster completely to the left (outlet open)
- 0.7 - 1.1 V



- 3.5 - 4.8 V
23 13.0
Left air outlet adjuster Move left air outlet adjuster completely to the right (outlet closed)

Move left air outlet adjuster completely to the left (outlet open)
- 0.6 - 0.9 V



- 3.9 - 4.5 V
23 7.0
Left air outlet feedback potentiometer Move left air outlet adjuster completely to the right (outlet closed)

Move left air outlet adjuster completely to the left (outlet open)
- 0.7 - 1.1 V



- 3.5 - 4.8 V
23 12.0
Right air outlet adjuster Move right air outlet adjuster completely to the right (outlet closed)

Move right air outlet adjuster completely to the left (outlet open)
- 0.6 - 0.9 V



- 3.9 - 4.5 V
23 9.0
Right air outlet feedback potentiometer Move right air outlet adjuster completely to the right (outlet closed)

Move right air outlet adjuster completely to the left (outlet open)
- 0.7 - 1.1 V



- 3.5 - 4.8 V
23 14.0