Temperature gauge troubleshooting fj45 (1 Viewer)

[yomumsbum]

Gday everyone I would just like some ways of troubleshooting my temperature gauge (1979 fj45 2f) it does not move at all along with my oil pressure and alternator gauge. So far the only trouble shooting I have done is removing the temp sender, visual inspection (looked good) checked resistance from the terminal the gauge wire connects to and the bottom of the sender, it read no resistance, then I put the car in the on position No started and grounded the wire from the temp sender to the block ( no movement on gauge), next I tested for voltage from the temp sender and wire I got like 3v and I pulled the cluster out for a quick inspection didn’t notice anything .
I’m not sure if I even did these tests correctly would just like some advice and good trouble shooting methods,
Thanks very much

 

[fjwagon]

What has worked for in the past for me, disconnect the battery and clean the terminals with a wire brush at both ends. Terminals oxidized overtime, sometimes reseating them is all it needs to make good contact.

 

[45Dougal]

Since you have several gauges not reading, I'd suggest cleaning up the circular connector on the instrument panel. You might need to tighten the connectors up a bit if they're loose.

Secondly, sounds like your fuel gauge may also be misbehaving (it provides the regulated 7v for itself and to the temp gauge). Suggest cleaning up the contacts inside the fuel gauge or fitting an external silicone regulator.

 

[yomumsbum]

Since you have several gauges not reading, I'd suggest cleaning up the circular connector on the instrument panel. You might need to tighten the connectors up a bit if they're loose.

Secondly, sounds like your fuel gauge may also be misbehaving (it provides the regulated 7v for itself and to the temp gauge). Suggest cleaning up the contacts inside the fuel gauge or fitting an external silicone regulator.

Thanks for the advice mate very helpful I will give these a go.

 

[DylanH239]

If you take out your gauge cluster make sure to disconnect your battery you don’t want to smoke your amp gauge and wiring. The advice 45Dougal gave was is how I’d go about it just make sure your connections on the circle connector are clean and if you take the cluster out look at the condition of the circuit board. I will include pictures from my 1977 FJ40.

Back side of cluster circular connector can be seen on the right hand side of the circuit board with “key hole” in center.

Circle connector that controls some of the gauges.

 

[yomumsbum]

If you take out your gauge cluster make sure to disconnect your battery you don’t want to smoke your amp gauge and wiring. The advice 45Dougal gave was is how I’d go about it just make sure your connections on the circle connector are clean and if you take the cluster out look at the condition of the circuit board. I will include pictures from my 1977 FJ40.

Back side of cluster circular connector can be seen on the right hand side of the circuit board with “key hole” in center.
View attachment 3532227
Circle connector that controls some of the gauges.
View attachment 3532229

That’s great, thanks a lot. One other question what are the screws at the back of the gauges for mine were pretty rusty is that an issue?

 

[DylanH239]

That’s great, thanks a lot. One other question what are the screws at the back of the gauges for mine were pretty rusty is that an issue?

What you circled are 7mm nuts that hold your gauges in place in your cluster. You can clean them up mine were pretty clean so I didnt bother I would look at the mating surfaces where the nuts mate to the circuit board see if there’s any corrosion. There are also 7 screws to take off 4 located on the bottom of the cluster and 3 on the circuit board. 2 electrical connections one being a black wire at the “top” of the cluster that unscrews from the cluster with screw #7 and the other a white wire that will simply unplug when pulled. DO NOT PULL ON THE BLACK COVERS where the black and white wires terminate. Pull the clear end to the left of my #2 in the pic.I’ve included a pic with the screws and connections numbered. Once you have those off you can take off the circuit board,gently pry apart your cluster try not to tear the gasket and then you will be able to get to your gauges.

 

[DylanH239]

Video of cluster here is a video of my cluster right before I took off my circuit board. Once you get all the nuts off the gauges, screws undone and 2 electrical connections undone you should be able to lift the circuit board off and it will look like this picture below. Then you would gently try and separate the cluster you can see the gasket around the edges tan in color. Then you will get your gauges.

 

[45Dougal]

That’s great, thanks a lot. One other question what are the screws at the back of the gauges for mine were pretty rusty is that an issue?

View attachment 3532315

The screws are the electrical contacts to the pcb. Presumably you've removed the nuts? If not then that is your problem.

Personally I pry open the tabs on the outside of the case and remove the front cover rather than the back - pros and cons to both though.

If you need s silicon regulator then can work something like this with an LM7808 and a couple of diodes...

 

[yomumsbum]

What you circled are 7mm nuts that hold your gauges in place in your cluster. You can clean them up mine were pretty clean so I didnt bother I would look at the mating surfaces where the nuts mate to the circuit board see if there’s any corrosion. There are also 7 screws to take off 4 located on the bottom of the cluster and 3 on the circuit board. 2 electrical connections one being a black wire at the “top” of the cluster and the other a white wire that will simply unplug when pulled. I’ve included a pic with the screws and connections numbered. Once you have those off you can take off the circuit board,gently pry apart your cluster try not to tear the gasket and then you will be able to get to your gauges. View attachment 3532359

The screws are the electrical contacts to the pcb. Presumably you've removed the nuts? If not then that is your problem.

Personally I pry open the tabs on the outside of the case and remove the front cover rather than the back - pros and cons to both though.

If you need s silicon regulator then can work something like this with an LM7808 and a couple of diodes...

View attachment 3532681

View attachment 3532682

thanks mate yeah I don’t have any wires connected to those 7mm nuts here’s the only photo I could find I’m at work atm

 

[DylanH239]

thanks mate yeah I don’t have any wires connected to those 7mm nuts here’s the only photo I could find I’m at work atm

View attachment 3533342

This shows how to disassemble the cluster and take the front cover off to get to the gauges if you don’t want to go the route I went Cluster disassembly video

I DID NOT have the wires that 45Dougal has running to the nuts/screws so I’m assuming yours would be more similar to my setup not 100% certain since I have a 1977 FJ40.I’m assuming you should be able to reference some of the pictures I provided of the back of my cluster if needed. Make sure to disconnect your battery BEFORE you take out your cluster and if you do take the cluster out share some pictures so we can see what your working with. If you need any advice/tips taking the cluster out of the vehicle just let us know.

 

[45Dougal]

Sorry for any confusion - the wires on mine are for my external regulator (my fuel gauge regulator is toast), so this is a mod - in case you need it just let me know and I'll elaborate.

Your nuts look a bit rusty to me, I'd definitely clean them up and hopefully all works as it should.

Maybe worth checking why they're rusty (windscreen seal / vent leaking).