Air Conditioning Signal Circuit: Prelude
- Turn ignition off. Disconnect A/C pressure switch and A/C diode connectors. See A/C SIGNAL COMPONENT LOCATIONS table. Turn ignition on. Backprobing, measure voltage between PCM connector "A" (32-pin connector) terminal No. 9 (Brown/Black wire) and PCM connector "C" (31-pin connector) terminal No. 5 (Blue/Orange wire). See Figure and Figure
. If battery voltage does not exist, go to next step. If battery voltage does exist, go to step 3.
- Turn ignition switch off. Disconnect PCM connector "C" (31-pin connector). Check continuity of Blue/Orange wire between body ground and PCM connector "C" (31-pin connector) terminal No. 5. If continuity exists, repair short in Blue/Orange wire between A/C pressure switch and PCM connectors. See WIRING DIAGRAMS article. If continuity does not exist, substitute a known-good PCM and retest. See SUBSTITUTING POWERTRAIN CONTROL MODULE under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - PRELUDE article. If symptom or indication goes away, replace original PCM. If symptom or indication does not go away, inspect A/C system. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
- Turn ignition off. Reconnect A/C pressure switch and A/C diode connectors. Turn ignition on. Backprobing, momentarily connect a fused jumper wire between PCM connector "A" (32-pin connector) terminals No. 9 (Brown/Black wire) and No. 17 (Pink/Blue wire), several times. If A/C compressor clutch does not make a clicking sound, go to next step. If A/C compressor clutch makes a clicking sound, go to step 5.
- Backprobing, momentarily connect a jumper wire between body ground and A/C compressor clutch relay connector terminal No. 4 (Pink/Blue wire), several times. See Fig 1. See A/C SIGNAL COMPONENT LOCATIONS table. If A/C compressor clutch makes a clicking sound, repair open in Pink/Blue wire between A/C compressor clutch relay and PCM connectors. See WIRING DIAGRAMS article. If A/C compressor clutch does not make a clicking sound, inspect A/C system. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
- Start engine. Turn A/C and blower motor switches on. If A/C does not operate, go to next step. If A/C operates, A/C signal is okay.
- Backprobing, measure voltage between PCM connector "A" (32-pin connector) terminal No. 9 (Brown/Black wire) and PCM connector "C" (31-pin connector) terminal No. 5 (Blue/Orange wire). See Figure and Figure
. If voltage reading is not less than one volt, repair open in Blue/Orange wire between A/C pressure switch and PCM connectors. See WIRING DIAGRAMS article. If voltage reading is less than one volt, substitute a known-good PCM and retest. See SUBSTITUTING POWERTRAIN CONTROL MODULE under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - PRELUDE article. If symptom or indication goes away, replace original PCM. If symptom or indication does not go away, inspect A/C system. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
Courtesy of AMERICAN HONDA MOTOR CO., INC.