Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSHONDA2000ACCORD EX SEDAN L4-2254CC 2.3L SOHC (VTEC) MFIREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSTESTING AND INSPECTIONCOMPONENT TESTS AND GENERAL DIAGNOSTICSA/C SIGNAL CIRCUIT TROUBLESHOOTING
2000 Honda Accord EX Sedan L4-2254cc 2.3L SOHC (VTEC) MFI
A/C Signal Circuit Troubleshooting
2000 Honda Accord EX Sedan L4-2254cc 2.3L SOHC (VTEC) MFISECTION A/C Signal Circuit Troubleshooting
A/C Signal Circuit Troubleshooting
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/PCM connector terminals A27 and B20.
Is there approx. 5V?
YES - Go to step 5.
NO - Go to step ~2.
5. Turn the ignition switch OFF.
6. Reconnect the A/C pressure switch connector.
7. Turn the ignition switch ON (II).
8. Momentarily connect ECM/PCM connector terminals A17 and B20 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/PCM connector A (32P)
14. Check for continuity between body ground and ECM/PCM connector terminal A27.
Is there continuity?
YES - Repair short in the wire between the ECM/PCM (A27) and the A/C pressure switch.
NO - Substitute a known-good ECM/PCM and recheck. If the prescribed voltage is now available, replace the original ECM/PCM. 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.
NOTE: The under-hood fuse/relay box 16P connector is on the bottom of the fuse box. When you unbolt and invert the fuse box, leave the upper cover on to prevent short circuits.
Is there a clicking noise from the A/C compressor clutch?
YES - Repair open in the wire between the ECM/PCM (A17) and the A/C clutch relay.
NO - Check the A/C system for other symptoms.
16. Measure voltage between ECM/PCM connector terminals A27 and B20.
Is there less than 1.0 V ?
YES - Substitute a known-good ECM/PCM and recheck. If the symptom/indication goes away, replace the original ECM/PCM. If not, inspect the air conditioning system.
NO - Repair open in the wire between the ECM/PCM (A27) and the A/C pressure switch.
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/PCM connector terminals A27 and B20.
Is there approx. 5V?
YES - Go to step 5.
NO - Go to step ~2.
5. Turn the ignition switch OFF.
6. Reconnect the A/C pressure switch connector.
7. Turn the ignition switch ON (II).
8. Momentarily connect ECM/PCM connector terminals A17 and B20 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/PCM connector A (32P)
14. Check for continuity between body ground and ECM/PCM connector terminal A27.
Is there continuity?
YES - Repair short in the wire between the ECM/PCM (A27) and the A/C pressure switch.
NO - Substitute a known-good ECM/PCM and recheck. If the prescribed voltage is now available, replace the original ECM/PCM. 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.
NOTE: The under-hood fuse/relay box 16P connector is on the bottom of the fuse box. When you unbolt and invert the fuse box, leave the upper cover on to prevent short circuits.
Is there a clicking noise from the A/C compressor clutch?
YES - Repair open in the wire between the ECM/PCM (A17) and the A/C clutch relay.
NO - Check the A/C system for other symptoms.
16. Measure voltage between ECM/PCM connector terminals A27 and B20.
Is there less than 1.0 V ?
YES - Substitute a known-good ECM/PCM and recheck. If the symptom/indication goes away, replace the original ECM/PCM. If not, inspect the air conditioning system.
NO - Repair open in the wire between the ECM/PCM (A27) and the A/C pressure switch.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.