Type S M/T Model

A/C Pressure Switch Circuit Troubleshooting (Type S M/T Model)

1. Disconnect the A/C pressure switch 2P connector.
2. Turn the ignition switch ON (II).




3. Measure the voltage between the No. 2 terminal of the A/C presure switch 2P connector and body ground.

Is there about 5 V?

YES - Go to step 4.

NO - Go to step 10.

4. Turn the ignition switch OFF.




5. Check for continuity between the No. 1 and No. 2 terminals of the A/C pressure switch.

Is there continuity?

YES - Go to step 6.

NO - Go to step 11.

6. Reconnect the A/C pressure switch 2P connector.
7. Disconnect climate control unit connector B (20P).
8. Turn the ignition switch ON (II).




9. Measure the voltage between the No. 11 terminal of climate control unit connector B (20P) and body ground.

Is there about 5 V?

YES - Check for loose wires or poor connections at climate control unit connector B (20P) and at the A/C pressure switch 2P connector. If the connections are good, substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit.

NO - Repair open in the wire between the climate control unit and the A/C pressure switch.




10. Using a Backprobe Set, measure the voltage between the No. 21 terminal of ECM connector A (31P) and body ground with the ECM connectors connected.

Is there about 5 V?

YES - Repair open in the wire between the ECM and the A/C pressure switch.

NO - Check for loose wires or poor connections at ECM connector A (31P). If the connections are good, substitute a known-good ECM, and recheck. If the symptom/indication goes away, replace the original ECM.

11. Check for proper A/C system pressure.

Is the pressure within specifications?

YES - Replace the A/C pressure switch.

NO - Repair the A/C pressure problem.