FJ40 Cluster Headache - Gas / Temp gauge works when initially installed and cranked - upon recranking, it does not work (1 Viewer)

[cvan1971man]

I have been dealing with a speedo / cluster headache for a few months now.

When we originally rebuilt this FJ40, we had 2 clusters. One of them was from the wrong year and the other we did not know if it worked or not.

We made a mistake and bought a cluster off of amazon off of someone's recommendation as they stated that it was a good replacement. The pins on the back of the cluster were larger than on the OEM cluster and spread out the connectors on the plug.

After we realized our mistake we found someone here on Mud that could rebuild the cluster. It worked great for probably 8 months. Then one day the fuel and temp gauge did not work.

I have pulled the cluster out and made sure that the plug is fully seated on the back of the cluster probably 4-5 times. I have also made sure that the two power wires on the right hand side of the cluster are bolted snug.

The last 5-6 times that I have pulled the cluster out this weekend, the gas and temp gauge worked upon cranking the engine. It worked until I I turned the engine off and recranked it.
It seems like the whole cluster works upon the first crank and then on the 2nd crank the gas / temp gauge does not work.

Any ideas???

 

[CruiserInProgress]

I have been dealing with a speedo / cluster headache for a few months now.

When we originally rebuilt this FJ40, we had 2 clusters. One of them was from the wrong year and the other we did not know if it worked or not.

We made a mistake and bought a cluster off of amazon off of someone's recommendation as they stated that it was a good replacement. The pins on the back of the cluster were larger than on the OEM cluster and spread out the connectors on the plug.

After we realized our mistake we found someone here on Mud that could rebuild the cluster. It worked great for probably 8 months. Then one day the fuel and temp gauge did not work.

I have pulled the cluster out and made sure that the plug is fully seated on the back of the cluster probably 4-5 times. I have also made sure that the two power wires on the right hand side of the cluster are bolted snug.

The last 5-6 times that I have pulled the cluster out this weekend, the gas and temp gauge worked upon cranking the engine. It worked until I I turned the engine off and recranked it.
It seems like the whole cluster works upon the first crank and then on the 2nd crank the gas / temp gauge does not work.

Any ideas???

I recently attempted to revive the speedo and gauges for my 79 that had been sitting for many years. I'm still working on it but here are a few ideas for you:

- pin connections are only one segment of continuity between sensor and gauge. I pulled apart my speedo and removed all gauges, then cleaned all points of contact. That circuit board on the rear of the speedo gets tarnished over the years, including where the gauges mount. To pull it apart, you may need to loosen the gauges first to clear the housing.

- once you've done all that, you can plug in the speedo without installing into the dash to check function, and if necessary, to check voltages. But, be very careful not to short anything to that metal dash. Lots of gauge terminals sticking out (I taped mine). In my case I left the 3-pin connector unplugged, which I believe only powers the ammeter. Note, earlier models supplied 50 amps to the ammeter, but later models like mine reduced that via shunt (fusible link).

- pull up a copy of the FSM (free downloads are available online), which has some diagnostic troubleshooting info including proper voltages on various pins. You can probe voltages when your gauges are working and when they're not to see where the fault lies.

- about your specific issue with your gauges, check the traces on the speedo circuit board and see which pins on the road connector go to what gauge terminals. On my 79 three of the gauges share 12v. The ammeter is independent, getting power from the 3-pin connector. Anyway, trace them all out to better understand interconnections.

Good luck!

 

[archie73]

Any progress? My gas and temp gauges just stopped working. I’ve only had time to check the fuse block and fuse. Both seemed good. I’ll take any leads you’ve got. Thanks

 

[Otis]

I just resolved this problem on my 1980 FJ40 after cleaning the voltage regulator contacts on the fuel gauge following the method in this video: Toyota FJ40 Fuel Gauge Voltage Regulator Test/Repair

Thanks for the video @Hodakaguy!

 

[45Dougal]

Sounds like you have a bad connection somewhere.
You clearly have power to the engine, otherwise it wouldn't run, so that rules out your ignition switch, but it's still worth checking the connector on the column and reseating it with some contact cleaner.
Next thing to check would be your heater fuse to see if it had good continuity - this provides power to the gauges (*there may be variations between years - check that you have 12v on both sides of all fuses and make sure they're well gripped and clean).
Next up is the circular connector - seems like you've covered that but watch for corrosion.
After that is the voltage regulator inside the fuel gauge - notoriously unreliable at this age - clean, adjust, clean, fiddle, near with a small hammer in frustration, or just completely replace with a solid state regulator.
Hope some of that helps. Good luck

 

[JVZii]

Hey I am that guy on mud that rebuilt this cluster .

@cvan1971man sent me the cluster back. I rechecked everything and was kind of able to reproduce the problem on the bench. I think that once the fuel gauge voltage regulator got warm it stopped pulsing and then stopped powering the fuel and temp gauge. I have not seen this before but I kind of makes sense. I replaced the fuel gauge and tested it with the bench-o-matic 3000 and I think everything is good.

I am anxious to see if it works for you.

 

[cvan1971man]

Anyone who has a cluster problem, JVZii is the guy to go to, to get it fixed!!!