Coolant Temperature Gauge Troubleshooting

Before testing, check the No. 9 (10 A) fuse in the under-hood fuse/relay box and the No. 10 (7.5 A) fuse in the under-dash fuse/relay box.

1. Start the engine, and check the ECM/PCM for DTCs with the HDS.

   Are there stored DTCs in the ECM/PCM? 

   YES  - Troubleshoot the cause of the ECM/PCM DTC (see GENERAL TROUBLESHOOTING INFORMATION ), and recheck.

   NO  - Go to step  2.

2. Check for DTCs in the body electrical system with the HDS.

   Is a DTC indicated? 

   YES  - Troubleshoot the cause of the body electrical system DTC (see TROUBLESHOOTING ), and recheck.

   NO  - Go to step  3.

3. Do the communication line check with the self-diagnostic procedure (see ENDING THE SELF-DIAGNOSTIC FUNCTION  ).

   Is the word "Error" indicated on the odo/trip meter display? 

   YES  - The gauge control module cannot receive the signal from the multiplex control unit and the ECM/PCM. Check for an open in the WHT and RED wire (gauge control module connector terminals No. 28 and No. 29).

   NO  - Go to step  4.

4. Do the gauge control module drive circuit check with the self-diagnostic procedure (see ENDING THE SELF-DIAGNOSTIC FUNCTION  ).

   Does the temperature gauge needle sweep from the minimum position to the maximum, then return to the minimum position? 

   YES  - Go to step  5.

   NO  - Replace the gauge control module.

5. Substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), and recheck.

   Does the symptom/indication go away? 

   YES  - Replace the ECM/PCM.

   NO  - Substitute a known-good gauge control module. If the symptom/indication goes away, replace the gauge control module.