P1450

DIAGNOSTIC TROUBLE CODES P145O, P1451
A/C relay, control module output, no continuity or shorting to ground/batt+

Fault Symptom.
A/C function absent or faulty.

Condition
In the event of a short circuit or open circuit a diagnostic trouble code will be generated.

Diagnostic Procedure.
1. Connect a Scan Tool.
Select "ACTIVATE".
Select "AC RELAY".
- This command activates the A/C relay at a frequency of 0.5 Hz for 30 seconds.
- Listen for the sound of the relay clicking.

If the A/C relay and the compressor circuit are operative, it is possible to both see and hear the magnetic clutch in operation.
If the relay clicks, continue with step 4.
If it does not, continue with step 2.

2. Connect a BOB.
Start the engine and run it at idling speed.
Engage and disengage the compressor as follows:
^ Manual A/C - fan ON and A/C button depressed
^ ACC - AUTO-activated
- ECON disengaged

Check the voltage across pins 14 and 40. It is the input, A/C request, that according to status controls the output and consequently the A/C relay.
The voltage should be about 12 V when the compressor is running and about 0 V when it is not.

If the voltage is OK, continue with step 3.
If it is not, continue at "A/C", at Diagnosis without Trouble Codes. A/C





3. Check the voltage across pins 25 and 37, i.e. control of the A/C relay.
The voltage should be about 12 V when the compressor is running and about 0 V when it is not.

If the voltage is OK, continue at "A/C" at Diagnosis without Trouble Codes. A/C
If the voltage is not OK, check the lead between pin 25 of the control module and pin 85 of the A/C relay for continuity/shorting.
- The resistance of the A/C relay, taking a measurement across pins 85 and 86, the resistance should be about 85 ohms.
If there is no relevant cause of the fault, continue at "Procedure Before ECM Replacement".

4. Clear the diagnostic trouble code and drive the car to see whether the DTC is generated again.

If the diagnostic trouble code is generated again, continue at "Procedure Before ECM Replacement". Component Tests
If the trouble code is not generated again the remedial measure taken was correct, otherwise the fault is of intermittent type.