Sun Temp Gauge Technical Help

[Too Many Projects]

The sender may not be grounding with too much paste on the threads. With the engine warm, hold a screw driver against the body and touch the cylinder head, Have Tracy watch the gauge for movement.

[SuperNovaSS]

Originally Posted by Too Many Projects

The sender may not be grounding with too much paste on the threads. With the engine warm, hold a screw driver against the body and touch the cylinder head, Have Tracy watch the gauge for movement.

Also, if you quickly ground the sender wire with the ignition on the gauge needle should flicker.

Jason

[napa68]

There is power going into the gauge, but nothing coming out going to the sender. I checked for power going to the sender first of all (nothing) and then again at the output on the back of the gauge.

I then took it a step further to check for resistance in the wire going from the back of the gauge to the sender, and it's perfect.

[juliosz]

The wire going to the sensor is ground only. As the sensor heats up, it gradually opens the path to ground causing the gauge to display the current coolant temp.

[turbo69bird]

Originally Posted by juliosz

The wire going to the sensor is ground only. As the sensor heats up, it gradually opens the path to ground causing the gauge to display the current coolant temp.

So is this correct?

[juliosz]

Originally Posted by turbo69bird

So is this correct?

Yep, I’ll break down the diagnosis,
1. Ignition On, using a test light connected to ground, probe the battery terminal at the back of the gauge. Test light should light up. If not, check fuse. If fuse good, check wire.
2. If you have battery at the gauge, ignition On, find a GOOD ground and jump to the sensor terminal at the back of the gauge. Gauge needle should sweep to its limit. If it does, gauge is good, move to step 3. If it does not sweep, replace gauge.
3 Ignition On, Again, using a GOOD ground, disconnect the sensor and jump from ground to the sensor wire terminal. If the gauge pegs again, sensor wire is good, go to step 4. If it does not, you have an open circuit in the sensor wire between the gauge and sensor.
4. Using a volt ohm meter, check for continuity between the body of the sensor(not the center terminal) and the intake manifold, you should have continuity, if you do, the sensor is bad. If you don’t have continuity, remove sensor and clean excess gook from threads, reseal and reinstall.

[napa68]

Strangely, I did check the gauge again for power where it comes out of the gauge, but when I ground the power lead going to the sender, it sweeps the gauge.

One of two scenarios.
1. I do not know how to properly use a test light.
2. The Sun gauge works a bit differently than stock arrangements.

On the bright side, the gauge appears to be good. The downside is the sender for these is tough to find.

At any rate, the problem is solved for now. Thanks to everyone who took the time and effort.

Tim