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914World.com _ 914World Garage _ Temp Gauge Troubleshooting

Posted by: Amphicar770 Aug 25 2016, 11:59 AM

Hi All,

Car is now running great following all the work and subsequent tweaking addressed earlier.

One thing not working, pretty certain it did before engine drop, is the temp gauge.

I have checked the obvious, wire connections at both ends. even replaced connector on green wire in engine compartment. All the other gauges work as they should.

If I turn the key I do see the temp gauge move slightly so that tells me it is getting power. But, beyond that, the needle just sits near the bottom. It is the VDO gauge with no numbering, I think it uses some oddball sending unit.

Anyhow, just wondering what troubleshooting procedure I should follow. I assume using voltmeter / ohm-meter is next step but not sure what I am looking at or for.

Thanks.

Mike

Posted by: porschetub Aug 25 2016, 12:44 PM

[quote name='Amphicar770' date='Aug 26 2016, 05:59 AM' post='2390017']
Hi All,

Car is now running great following all the work and subsequent tweaking addressed earlier.

One thing not working, pretty certain it did before engine drop, is the temp gauge.

I have checked the obvious, wire connections at both ends. even replaced connector on green wire in engine compartment. All the other gauges work as they should.

If I turn the key I do see the temp gauge move slightly so that tells me it is getting power. But, beyond that, the needle just sits near the bottom. It is the VDO gauge with no numbering, I think it uses some oddball sending unit.

Anyhow, just wondering what troubleshooting procedure I should follow. I assume using voltmeter / ohm-meter is next step but not sure what I am looking at or for.

Thanks.

Most likely your gauge is ok if it moves when the key is on,you could try grounding it and see if it pegs out to max reading which it should do.
I found one of my spare temp gauge insets and have it in front of me,I can't remember if its from a 911 or 914 gauge,however I'am thinking you will need a sender rated at 150 degrees celcius max,if you have that and your wiring is 100% yours is unit is faulty.
If you aren't sure what your gauge is rated to shine a torch at angle to the top of the insert VDO put the numbers in very small letters up there corresponding with the 4 marked temp lines.
I prefer to use VDO senders with VDO gauges.
Good luck.

Posted by: 76-914 Aug 25 2016, 01:28 PM

You can check the sender. What are the ohm readings when cold vs. fully warmed up? Ohm out that green sending wire from sender to spade connector and then the entire length. That green wire didn't get ripped during the install, did it? IIRC, there is a bare metal tab(s) that holds the wire against the engine before the spade connection. Is the wire grounded out on a clamp? A quick ohm check from the disconnected green wire (both ends) to ground will show it if so.