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Heater Control Power and Ground Circuit Troubleshooting

WARNING: This page is about a different car, the 2009 Honda S2000 and 2008 Honda S2000. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check the No. 54(30 A) fuse in the main under-hood fuse/relay box, and the No. 20 (7.5 A) and No. 25 (7.5 A) fuses in the under-dash fuse/relay box.

    Are the fuses OK? 

    YES-  Go to step  2.

    NO-  Replace the f use(s), and recheck.

  2. Disconnect the heater control panel 30P connector.
  3. Turn the ignition switch to ON (II).
  4. Measure the voltage between the No. 30 terminal of the heater control panel 30P connector and body ground.

    Is there battery voltage? 

    Fig 1: Measuring Voltage Between Terminal Of Heater Control Panel 30P Connector And Body Ground
    G05115915Courtesy of AMERICAN HONDA MOTOR CO., INC.

    YES-  Go to step  5.

    NO-  Repair open in the wire between the No. 20 (7.5 A) fuse in the under-dash fuse/relay box and the heater control panel.

  5. Turn the ignition switch to LOCK (0).
  6. Measure the voltage between the No. 29 terminal of the heater control panel 30P connector and body ground.
    Fig 2: Measuring Voltage Between Terminal Of Heater Control Panel 30P Connector And Body Ground
    G05115916Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    YES-  Go to step  7.

    NO-  Repair open in the wire between the No. 25 (7.5 A) fuse in the under-dash fuse/relay box and the heater control panel.

  7. Check for continuity between the No. 26 terminal of the heater control panel 30P connector and body ground.
    Fig 3: Checking Continuity Between Terminal Of Heater Control Panel Connector And Body Ground
    G05115917Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES-  Check for loose wires or poor connections at the heater control panel 30P connector. If the connections are good, substitute a known-good heater control panel, and recheck. If the symptom indication goes away, replace the original heater control panel.

    NO-  Check for an open in the wire between the heater control panel and body ground. If the wire is OK, check for poor ground at G402.