Temperature Gauge Erratic

[sdb999]

89' 22re, 5spd, 350k
For years the Stewart Warner mechanical gauge was strapped to the steering column due to a non-responsive temp gauage....so ghetto it had to go.

Pulled cluster and cleaned all circuit board terminals, connectors, checked continuity back to block and sender and by some miracle it works! Sort of.

Now the gauge works most of the time, really much better, BUT every now and then it will spike to running temp at KOEO then return to normal operation AND since the fix I've received two CEL codes: 4 and 6. 4: Temp Circuit 6: Igniter. Cleared the codes and only 4 has returned (gauge works fine) so I'm ignoring 6 for now.

So,
1. Is there a ground somewhere I missed? I only focused on the grounds on the cluster and had good continuity.
2. Could it be the sender itself? I have a spare so might just throw that in.
3. Anything else? Could code 4 be referring to some other Temp Sensor?

Thanks all, S.

 

[flyinhawaiian01]

There's a complete test for the temp sensor in the manual, basically boiling the temp sensor and checking its resistance iirc. It sounds like the gauge is working correctly after you cleaned it, but the sensor sounds like its possibly broken. Too bad too, I just sold one 2 weeks ago from my '85 supra, they are the same sensor for both vehicles!

 

[sdb999]

Replaced sensor with known new, no change. I've been driving it with the instrument cover removed but cluster in place. Light tap on top of the cluster or rooting under the dash sometimes invokes/clears the issue. It's got to be in or very near the cluster. I was really hoping someone had been here before, I'd rather have teeth pulled than chase intermittent electrical faults. I suspect a ground somewhere, I'll have to start digging.

 

[grumpin]

Here's some ideas, if you haven't seen this yet.

Definitive Temp Gauge Fix! - YotaTech Forums

There is a ground under the drivers side kick panel. I did all this and mine will normally, depending on the outside temperature, go almost half way up and stay there. Sometimes when its cold out it will go down and come up with the temperature. It will go higher if the engine gets above say 210°. I found that out when my radiator needed to be replaced. I put a aftermarket gauge in it.

Aftermarket temp gauge - YotaTech Forums

 

[Quatre Coureur]

My temp gauge is also a bit faulty. But there is a cure well known to most 1st Gen owners. As you're driving, you tap the gauge 3 times(no more, no less!), then you swear(fkn, GD, pos!), then tap harder 3 more times(not too hard!)then, wait for it, it magically starts functioning exactly as God and Toyota intended it too! Then you pat 'er on the dash and say your sorry for saying such nasty things about her. Repeat as necessary. :wink2:

 

[flyinhawaiian01]

If you're having to slap the dash to get it to read, then you definitely have a short or broken wire somewhere.

Pull the cluster and see if the winding(s) are broken away from their contacts. Pretty easy to fix if you're good with a soldering iron and some patience. Follow Grumpin's first link to see just how to fix the issue, its got lots of pics on how to fix the gauge if that's where the problem lies.

 

[sdb999]

After more probing it's definitely inside the cluster and I'll be tearing into that another tonight or tomorrow. The only meaningful discovery last night was that the ground on the driver's kick panel has no relation to the temp gauge. Thank you all for the helpful thoughts and links.
Take Care, S.

 

[sdb999]

Full disassembly into the gauge down to the coils that drive the needle. Nothing amiss, no broken wires or anything else. Cleaned all connections and reassembled. Working well for the time being, we'll see.

 

[rustED_]

Does the gauge still spike and then go down? I had this problem, then after reading some info on 4crawler's site and his description of the problem sounded just like what was going on with mine. He installed a 2 stage Toyota thermostat P# 90916-03070 and it did the trick. I installed the same thermostat a few months back and haven't had the temp spike since, I have a aftermarket mechanical temp gauge and it never spikes, and it runs at 190°

Toyota 4Runner and Pickup: Cheap Tricks






.

 

[herpestes]

had somewhat of the same problem on my 84, the gauge would read fine that at times would go to cold. r&r the temperature gauge from the cluster and it fixed the problem.