Temperature Gauge

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Datsun 1200 comes with a full temperature gauge in the dash, controlled electrically by the Thermal Transmitter (sender) that is screwed into the cylinder head.

Also see: Water Temperature Gauge in Instruments and Controls

Thermal Transmitter

The temperature sender (sensor) is called the thermal transmitter. If varies resistance according to temperature.

Part Numbers:

• 25080-89900 GAUGE-TEMP ENGINE UNIT
• 25251-30100 NUT

Transmitter is at very front of right side

Tranmitter at left side, pointing up> it has a threaded collar nut to hold it in.

Transmitter at right front corner of head (in the photo: left side of front of head)

Troubleshooting

First, clean the connections of the wire to the thermal transmitter (engine temp sensor).

Yellow wire just about hose clamp
Remove the wire and clean the connector. Replace. Make sure the wire fits tight.

• If both fuel and temperature gauges do not work at all, the fuse is likely burnt out. Inspect the fuse. If the fuse is good, the instrument panel voltage regulator may be bad

• If both fuel gauge and temperature gauge read incorrectly (high or low) or fluctuate, the problem is likely the shared instrument panel voltage regulator. But first check the wiring connections. They may be loose or corroded.

• If gauge reads MAX hot with ignition OFF, gauge is defective.

• If gauge reads MAX hot with ignition ON, but cold with ignition OFF, transmitter is bad

• Ground sensor wire at engine. If gauge fluctuates, gauge is bad

Accuracy Test

• Buy a 116-ohm resistor at Radio Shack or other electronics store.

1. At the engine, locate the thermal transmitter:

2. Pull the wire off the transmitter and put a 116-ohm resistor from the wire to earth/ground
3. Turn IGN switch to "ON". Gauge should read 50C/122F, or between C and H ranges (in middle range)