Temp Guage Stopped Working last week and Gas gauge stopped working today (1 Viewer)

[cvan1971man]

We had the cluster rebuilt a year ago. Everything was working great until a week ago.

I had the cluster out to track down a speedometer issue and got that rectified.

Shortly thereafter, I noticed that the temp gauge stoped working. Today my son filled up the FJ and noticed that the gas gauge stopped working. I can understand the temp gauge stop working and needing to replace something like the water temp sending unit, but not the temp gauge and the fuel gauge stopping within a week of each other.

the amp meter and oil gauges are working

Where would you start looking first?

 

[John Smith]

Start with making sure the temp and water gauge wires are attached to the senders, and they are good corrosion free connections. Are you sure you fully seated the harness on the back of the gauge cluster? Did you disconnect the battery before you pulled the gauge cluster? Use a multi-meter or power probe and test for continuity from the sender wire end to the gauge harness pin. There are steps in the FSM to test the gauges themselves.

 

[eaj71]

As noted corroded terminals.
Check your grounds

 

[RodrigzCrzr]

Also check your fuse block. Clean the terminals the fuses clip on too.

 

[cvan1971man]

Start with making sure the temp and water gauge wires are attached to the senders, and they are good corrosion free connections. Are you sure you fully seated the harness on the back of the gauge cluster? Did you disconnect the battery before you pulled the gauge cluster? Use a multi-meter or power probe and test for continuity from the sender wire end to the gauge harness pin. There are steps in the FSM to test the gauges themselves.

I never did pull the gauge cluster fully from the dash. I only pulled it out far enough so that I could make sure that the speedometer cable was fully connected. After I received the new speedometer cable I pulled the cluster out enough to replace the cable

 

[cvan1971man]

Also check your fuse block. Clean the terminals the fuses clip on too.

I put some sand paper on the fuse block terminals. Still no joy

 

[cvan1971man]

As noted corroded terminals.
Check your grounds

I pulled all of the fuses out and ran some sandpaper over them

 

[Engineer8000]

What year is your truck?

 

[cvan1971man]

'78 engine, tranny and tcase, everything else is pretty much a '73

 

[Engineer8000]

There is a 7V regulator in the fuel gauge that powers the fuel and temp gauges. Sounds like that may have failed which is common.

 

[cvan1971man]

There is a 7V regulator in the fuel gauge that powers the fuel and temp gauges. Sounds like that may have failed which is common

 

[cvan1971man]

Who sells the regulator?

 

[cvan1971man]

Is it difficult to replace

 

[DeskJock]

I can’t remember the thread- but IIRC it’s built into the speedometer unit. The thread I’m thinking of - someone Frankensteined a power transistor into the board.

The search feature here is your friend.

 

[Engineer8000]

You can search and find various threads on this subject. The 7V regulator is built into the fuel gauge, it could be the points are dirty, worth checking. If the regulator is bad, I and others have added a separate 7V regulator to the back of the cluster. Or you could replace the fuel gauge. Again, you can find threads and pictures of this.

 

[firemanj92]

I also want to point out, anytime you remove/unscrew the cluster it is HIGHLY recommended one disconnects the battery.