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TR2/3/3A ELECT TEMP GUAGE WIRING FOR TR-3?

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Bob_Burt

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While removing the center guage plate on my '58 TR-3A for refinishing, one of the wires (not the one to the sensor) from the Jaeger electric temp guage came loose and I can't for the life of me figure out where it goes!
The car is an older restoration and the PO replaced the origninal Lucas guage.
Any recommendations for power source/relay/other?

Thanks, Bob Burt
 
Bob,

Since the electric temp gauge is not original, you can be sure the wiring to it is not original either -so don't plan to use any color codes from any diagrams. I plan to also use a TR4 (electric) temp gauge in my TR3. I assume your gauge was working before you took it apart, so everything should be there to get it working again. However, when the gauge was installed, the PO *should* have installed a voltage regulator in line before it, so that readings might be more accurate. If so, you should find a little three pronged device (looks like a relay) with one wire connected to ground, another connected to a switched (with the key) hot, and the other going to the temp gauge (the ground may be in the form of a grounded mounting bolt). The other side of the temp gauge should be connected to the sending unit at the top front of the engine. There should be no need for any relays, since the power to operate a gauge is minimal.

The power side of the gauge might be wired directly to the power side of the fuel gauge, regardless of the added voltage regulator.

I hope this helps. Lets see some pictures of what you're doing.

Jer
 
Yep, I have one of those 3 prong devices mounted next to the heater! And I wondered what it was for. Problem solved, I think. I'll post again after I get everything hooked back up. I'm trying to figure out how to get my digital pictures down-sized to post - the dash looks great.

Thanks Jer - Bob Burt
 
Aloha Bob,

The voltage stabilizer is necessary to have the electric temperature gauge work reliably. If the voltage stabilizer is either removed or fails the gauge will act very erratically. At low idle revs the gauge will indicate a low temperature, as engine speed increases the temperature will rise rapidly. These actions don't reflect temperature changes but dynamo output voltage changes.
 
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