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Old 12-29-2017, 10:11 PM   #1
GM man
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fuel and temp gauge resistor

Since my LS swap, my fuel and temp gauges haven't worked. I've checked everything I know to check and nothing so far. The float and sending unit are new and there's continuity between the gauge and the tank and I'm pretty sure the ohms are the same between my original sending unit and the new one. I've even swapped out my gauge with another one I had and still no luck. I've got an aftermarket fuel gauge hooked up now and it's working fine. I'm down to it maybe being the resistor? I don't know what to check to see if its bad. And since my temp gauge isn't working either (and both worked fine before the swap) I thought maybe the resistor on it may be bad too??. I need some help from you electrical geniuses out there.
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Old 12-30-2017, 01:48 PM   #2
VetteVet
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Re: fuel and temp gauge resistor

................................
Quote:
Originally Posted by GM man View Post
Since my LS swap, my fuel and temp gauges haven't worked. I've checked everything I know to check and nothing so far. The float and sending unit are new and there's continuity between the gauge and the tank and I'm pretty sure the ohms are the same between my original sending unit and the new one. I've even swapped out my gauge with another one I had and still no luck. I've got an aftermarket fuel gauge hooked up now and it's working fine. I'm down to it maybe being the resistor? I don't know what to check to see if its bad. And since my temp gauge isn't working either (and both worked fine before the swap) I thought maybe the resistor on it may be bad too??. I need some help from you electrical geniuses out there.
We've discussed this many times on the forum so I'll go over it again.
Assuming you have a stock 72 gauge dash in your truck and the wiring is stock as well.

If your fuse panel is stock you can pull the fuel terminal wire and turn the key on and the fuel gauge should go to 2 O'clock. If it doesn't move or only goes up a little bit then you aren't getting battery voltage to the gauge. This test only includes the fuel gauge from the fuse panel and doesn't include the sending unit or the aftermarket gauge.

Disconnect the temperature gauge green wire on the engine block and touch it to ground with the key on. The temperature gauge should go to full hot. If it doesn't move then there is no power going to the gauge or it isn't grounded in the cluster panel or the panel isn't grounded. Also check the cluster panel fuse in the fuse panel. It might be something as simple as the fuse or it's connection in the panel. Lots of times the holders get corroded in the panel and just need cleaning.

If you are running the fuel injection on the LS, then you need the high pressure pump, and the LS sending unit in the fuel tank. What's the resistance reading on the tank sender empty to full?. it should be 0 to 90 ohms.

The engine block temperature sender would need a modified original stock sender for the 350 small block. These can be a turned down thread on the stock sender to fit the LS block.

Post back with the test results.
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