Checking Gas Gauge and Sending Unit (1 Viewer)

[Sky King]

This will be one of the things on my to do list this week to see if either or both are in working order. First question, with the gauge can I apply a full 12 volts to it to make it deflect or will that burn it out? If 12 volts is too much what's the best method with the instrument cluster out?

With the sending unit using an ohm meter what range should I read on it from the low position (empty) to the high position (full) ?

 

[1MAC]

1. Hook a bulb in series, or you risk burning out the gauge.
2. It depends what year. 17-120 Ohms is what I think mine is supposed to have.

 

[45Dougal]

Momentarily applying 12v should be OK for a quick test. Disconnect as soon as it deflects (few seconds max).
Preferably connect it to 7V with a series resistor to represent the sender.

Check the chassis manual for your model year for correct resistance - all available online here with a quick search.

If its not working as expected then clean the contacts in the internal voltage regulator or replace with a linear regulator.

 

[Sky King]

I had the dash on the work bench this morning and found three terminals on the back of the fuel gauge where I expected to find two. Which of the three do I momentarily apply voltage to to check the gauge ? One must be a ground, what's the third wire?

I'll also mention there is no wiring harness in the L C right now, I've just run a few wires so the motor will start and run while I work on it and I can drive it on my property. I'm trying to get the gas gauge working too so I can keep track of the fuel level. Any explanation of the three connections on the gauge will help in me getting it wired up until I get the complete wiring harness installed.

 

[Sky King]

I found this :

 

[45Dougal]

There are 4 connections.
The 3 screw terminals and ground via the metal case which is also connected to a pin on the circular connector.

1 - 12V input
2 - 7V output
3 - Sender connection via resistance to ground

4 - chassis to ground

 

[JVZii]

I found this :

This guy is good.

 

[germaneighter]

I found this :

Thanks for posting this! I performed this test last night and all was good. I will say that my first attempt was with a "used" 9V battery. The test light lit-up (but dim) and did not blink. I then used a fresh 9V and the test light blinked just as in the video for both parts of the test.

 

[Sky King]

Thanks for posting this! I performed this test last night and all was good. I will say that my first attempt was with a "used" 9V battery. The test light lit-up (but dim) and did not blink. I then used a fresh 9V and the test light blinked just as in the video for both parts of the test.

I'm glad you found that helpful! In my case my gauge tested bad and I'll be looking for a new one.

 

[JVZii]

I'm glad you found that helpful! In my case my gauge tested bad and I'll be looking for a new one.

I have gauges if you need one. Send me a pm if interested

Jack