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HVAC Control Power and Ground Circuit Troubleshooting
HVAC Control Power and Ground Circuit Troubleshooting1. Check the No. 30 (7.5 A) fuse in the under-dash fuse/relay box.
Is the fuse OK?
YES - Go to step 2.
NO - Replace the fuse, and recheck. If the fuse blows again, check for a short in the No. 30 (7.5 A) fuse circuit.
2. Disconnect the HVAC control unit 30P connector.
3. Turn the ignition switch ON (II).
4. Measure the voltage between the HVAC control unit 30P connector No. 15 terminal and body ground.
Is there battery voltage?
YES - Go to step 5.
NO - Repair open in the wire between the No. 30 (7.5 A) fuse in the under-dash fuse/relay box and the HVAC control unit.
5. Turn the ignition switch OFF.
6. Check for continuity between the HVAC control unit 30P connector No. 1 terminal and body ground.
Is there continuity?
YES - Check for loose wires or poor connections at the HVAC control unit 30P connector. If the connections are good, substitute a known-good HVAC control unit, and recheck. If the symptom/indication is still present, substitute a known-good HVAC control unit, and recheck.
NO - Check for an open in the wire between the HVAC control unit and body ground. If the wire is OK, check for poor ground at G402.