Sun Temp Gauge Technical Help

[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

[Too Many Projects]

Sounds like the gauge doesn't send current until it senses a ground. I think you are back to the sender not grounding in the head. You went from cast to aluminum too. The head should be well grounded thru the head bolts, but never say never if the builder put sealant on those bolts too.

[turbo69bird]

Originally Posted by 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 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

There’s a guy on EBay who reproduces those senders. He must know a fair amount about that particular gauge to make the senders no one else makes . Maybe send a message and ask for some pointers on testing . Is there someone close by you w a gauge you could wire in and test to see if it acts the same?

If you were concerned it was the sender not grounding just wrap a wire around the threads to the ground on the battery and see what it does. That should answer that question fairly quickly

[napa68]

Originally Posted by turbo69bird

There’s a guy on EBay who reproduces those senders. He must know a fair amount about that particular gauge to make the senders no one else makes . Maybe send a message and ask for some pointers on testing . Is there someone close by you w a gauge you could wire in and test to see if it acts the same?

If you were concerned it was the sender not grounding just wrap a wire around the threads to the ground on the battery and see what it does. That should answer that question fairly quickly

I have a sender on the way from him. I should see it mid this coming week.