Test B: Incorrect Temperature Gauge Indication

PINPOINT TEST B: INCORRECT TEMPERATURE GAUGE INDICATION

B1-B3:

B3-B5:

B5-B7:

Normal Operation
The temperature gauge is controlled by a shielded 5V reference signal sent from the instrument cluster through circuit 39 (RD/WH) to the engine coolant temperature (ECT) sender. The ECT sender is grounded through circuit 570 (BK/WH). As the engine coolant temperature increases, the ECT thermistor's resistance decreases from approximately 17.4 K ohms (cold) to 843 ohms (hot). The resulting change in voltage is interpreted by the instrument cluster, which commands the temperature gauge to sweep to the correct position.

Possible Causes
- circuit 39 (RD/WH) open, short to voltage or short to ground
- circuit 570 (BK/WH) open
- ECT
- instrument cluster