Coolant Temperature Gauge Circuit Troubleshooting

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

1. Start the engine, and check the malfunction indicator lamp (MIL).

   Does the MIL come and stay on? 

   1. YES  - Troubleshoot the cause of the ECM/PCM DTC (see GENERAL TROUBLESHOOTING INFORMATION ), and recheck.
   2. NO  - Go to step 2.
2. Check for a multiplex control unit DTC (see TROUBLESHOOTING ).

   Is any DTC indicated? 

   1. YES  - Troubleshoot the cause of the multiplex control unit DTC (see TROUBLESHOOTING ), and recheck.
   2. NO  - Go to step 3.
3. Do the communication line check with the self-diagnosis procedure (see Self-diagnostic Function  ).

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

   1. YES  - The gauge cannot receive the signal from the multiplex control unit, the keyless receiver unit, and the ECM/PCM. Check for an open in the GRY/ RED wire (gauge connector terminal A1).
   2. NO  - Go to step 4.
4. Do the gauge drive circuit check with the self-diagnosis procedure (see Self-diagnostic Function  ).

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

   1. YES  - Go to step 5.
   2. NO  - Replace the gauge assembly.
5. Substitute a known-good ECM/PCM, and recheck. Did the symptom/indication go away?
   1. YES  - Replace the ECM/PCM.
   2. NO  - Substitute a known-good gauge assembly. If the symptom/indication goes away, replace the gauge assembly.