Rallye cluster fuel gauge problems.

[kawahonda]

If it's reading 43, then your sender is successfully telling the gauge "I HAVE FUEL!"

You can rule out the sender, no need to mess with it anymore.

The problem is either your gauge or the wiring. Most likely the wiring.

Next steps:

1) Bypass the grounding strap on the sending unit and ground it to areas on the chassis. Does it work now?

2) Hook up a multi-meter to your sending unit lead and check that you are getting pulsating 5Vs with the keyswitch on "On"

1) or 2) will tell you your issue.

[Keith09]

I managed to crawl underneath the dash & with both posts disconnected measure 12 ohms across the gauge itself.  Can anyone verify if that is correct.

Also is there supposed to be a ground on the gauge side somewhere that i'm overlooking ?

[Keith09]

If it's reading 43, then your sender is successfully telling the gauge "I HAVE FUEL!"

You can rule out the sender, no need to mess with it anymore.

The problem is either your gauge or the wiring. Most likely the wiring.

Next steps:

1) Bypass the grounding strap on the sending unit and ground it to areas on the chassis. Does it work now?

2) Hook up a multi-meter to your sending unit lead and check that you are getting pulsating 5Vs with the keyswitch on "On"

1) or 2) will tell you your issue.


I made up a jumper & grounded from the sender directly to the neg battery post & still nothing.

I also bypassed the wire from the gauge to the sender & ran a jumper & still nothing.

Also i replaced the factory voltage regulator with a solid state type & i'm measuring 5.05 volts solid non pulsating at the sender.

The Temp & Oil pressure work perfect with the new regulator.

[Keith09]

Alright i found some information today, I bought a pack of resistors & bypassed the tank all together & ran a temp from the neg battery post through each resistor to the gauge & found that 8ohms is full & 32 ohms is empty and anything above 32 will hardly register.

I'm thinking the gauge must be at fault then

[7212Mopar]

Are the resistors you used has the resistance rating at 5 volt? If it is rated at higher voltage then the resistance might be different at 5 volt. I am not very good at electrical but I kind of remember the gauge works off of current heating up element to move the needle. the 5 volt power is from the voltage regulator at the instrument panel. I supposed you checked your have 5 volts. May be Cody can chime in.

[7212Mopar]

May be best to pull the sender to test and you can test the float if it is leaking. It is more work but not too bad. Sounds like your gauge is working when you ground it.

[734406PK]

Alright i found some information today, I bought a pack of resistors & bypassed the tank all together & ran a temp from the neg battery post through each resistor to the gauge & found that 8ohms is full & 32 ohms is empty and anything above 32 will hardly register.

I'm thinking the gauge must be at fault then

The fuel gauge is bad. It should read Empty @70-73 ohms, 1/2 @ 23-25 ohms and Full @ 10-13 ohms.

[Keith09]

Are the resistors you used has the resistance rating at 5 volt? If it is rated at higher voltage then the resistance might be different at 5 volt. I am not very good at electrical but I kind of remember the gauge works off of current heating up element to move the needle. the 5 volt power is from the voltage regulator at the instrument panel. I supposed you checked your have 5 volts. May be Cody can chime in.

Yes I replaced the voltage regulator with a new solid state type & I verified I'm getting solid 5.05 volts through the gauge.
I'm gonna pull the gauge in the next few days & bring it to an auto electric shop close by to verify before I spend more money needlessly.

[Keith09]

Well i'm very happy to report i found the issue & it turns out was the gauge itself.

It would still sweep all the way full if i grounded it & was reading 12 ohms

The new one reads 17 ohms for anyone else looking to troubleshoot.

[734406PK]

Great news! Equipped with the new solid state voltage regulator, you are better than new! 

[RUNCHARGER]

Thanks for posting the cause. A lot of times guys start a thread like this with no conclusion.

[734406PK]

Thanks for posting the cause. A lot of times guys start a thread like this with no conclusion.

Posting a successful repair can help other members with a similar problem. Congrats!