Inspection Procedure 27

CIRCUIT OPERATION
- The PCM increases the engine idle speed by driving the IAC motor when the automatic compressor-ECU sends a "A/C on" signal to the PCM.
- The automatic compressor-ECU detects how the air conditioning is applying load to the engine, and converts the information to a voltage signal (High voltage=low load, Low voltage=high load). This voltage signal is called "A/C switch 2 signal." The PCM receives this A/C switch 2 signal from the automatic compressor-ECU through terminal 61, and determines the idle-up speed according to the high or low air conditioning load.

TROUBLESHOOTING HINTS
The most likely causes for this code to be set are:
- Malfunction of the A/C control system.
- Open or shorted circuit, or improper connector contact.
- PCM failed.




WIRING DIAGRAM




CONNECTORS

DIAGNOSIS




STEP 1. Measure the voltage at the PCM connector C-40.
1. Measure the voltage between the terminal 61 and the ground under following condition. (Connectors should not be disconnected.)
a. Engine: Warm, idle
b. Outside temperature: 25° C (77 ° F) or higher

Standard value: 0 - 3 volts
(A/C temperature control: Maximum cooling position)

Battery positive voltage
(A/C temperature control: Maximum heating position)

If within specifications, go to Step 2.
If not within specifications, check the A/C system. Refer to Diagnosis.




STEP 2. Check the harness connector C-40 at the PCM for damage.
If harness connector C-40 is not damaged, replace the PCM. If the harness connector C-40 is damaged, repair or replace them. Refer to Harness Connector Inspection >. Then check the malfunction is eliminated.