Engine Coolant Temperature Gauge Test

Fig 1: Identifying Special Tool

Courtesy of MAZDA MOTORS CORP.

1. Disconnect ECT sender connector. Connect one lead of Fuel Thermometer SST  49 0839 285 to the sender connector (R/W) and the other lead to ground.
2. Set Fuel Thermometer SST  49 0839 285 to 300 ohms. Key ON. Wait one minute. The engine coolant temperature gauge should indicate C (cold). Key OFF.
3. Set Fuel Thermometer SST  49 0839 285 to 45 ohms. Key ON. Wait one minute. The engine coolant temperature gauge pointer should be in the one quarter range to mid range. Key OFF.
4. Set Fuel Thermometer SST  49 0839 285 to 18 ohms. Key ON. Wait one minute. The engine coolant temperature gauge should indicate H (hot). Key OFF. Return to INSTRUMENT CLUSTER PINPOINT TEST 2: INCORRECT TEMPERATURE GAUGE INDICATION .