M/T Model
A/C Signal Circuit TroubleshootingM/T Model
1. Turn the ignition switch OFF.
2. Disconnect the A/C pressure switch connector.
3. Turn the ignition switch ON (II).
4. Measure voltage between ECM connector terminals A26 and E21.
Is there approx. 5 V?
YES - Go to step 5.
NO - Go to step 12.
5. Turn the ignition switch OFF.
6. Reconnect the A/C pressure switch connector.
7. urn the ignition switch ON (II).
8. Momentarily connect ECM connector terminals A26 and E12 with a jumper wire several times.
Is there a clicking noise from the A/C compressor clutch?
YES - Go to step 9.
NO - Go to step 15.
9. Start the engine.
10. Turn the blower switch ON.
11. Turn the A/C switch ON.
Does the A/C operate?
YES - The air conditioning signal is OK.
NO - Go to step 16.
12. Turn the ignition switch OFF.
13. Disconnect ECM connector E (31P).
14. Check for continuity between body ground and ECM connector terminal E21.
Is there continuity?
YES - Repair short in the wire between the ECM (E21) and the A/C pressure switch.
NO - Substitute a known-good ECM and recheck. If the prescribed voltage is now available (about 5 V), replace the original ECM. If not, check the A/C system for other symptoms.
15. Momentarily connect under-hood fuse/relay box 16 P connector terminal No.11 to body ground with a jumper wire several times.
Is there a clicking noise from the A/C compressor clutch?
YES - Repair open in the wire between the ECM (E21) and the A/C clutch relay.
NO - Check the A/C system for other symptoms.
16. Measure voltage between ECM connector terminal A26 and E21.
Is there less than 1.0 V?
YES - Substitute a known-good ECM and recheck. If the symptom/indication goes away, replace the original ECM. If not, inspect the air conditioning system.
NO - Repair open in the wire between the ECM (E21) and the A/C pressure switch.