Temperature gauge needle jumping

G'day all,

I'm at my wits end with trying to resolve an electrical gremlin with my 2002 GU III ZD30 and seek guidance / help please?

My coolant temperature sensor on start up 'jumps' to half way then comes down and 'flickers' from time to time. I took the girl for a drive and she was, by the gauge, over-heating as if I lost all my coolant at one location.

I pulled over and there were no leaks, the radiator and surge tank were GTG as well as the radiator cap.

Since I started investigating, I found that the Temperature Sensor on the front of the block, had 0.8 - 1.2 Ohms resistance in the positive wire and slightly less in the earth (just old wiring); I have changed these out and I'm getting 4.9 VDC at the sensor when the ignition is on and I'm down to 0.3 Ohms resistance from the sensor to the computer.

I've also taken the instrument panel out to check that the connections were good on the back on the circuit board, all good there.

Unfortunately, I've just started the girl back up after replacing old wiring, and I also replaced the temperature sensor with a new one, the problem still happens.

I've searched through the forum but haven't seen anything like this.

Can anyone help please???

My sincerest thanks in advance.

Andrew

P.S. I'm in Canberra if anyone knows someone that can help down this way :(

Whats the earth wiring like? These Patrols are notorious for having shite earth connections.
Long shot but check and clean all earth points on chassis, body and block. Even run another earth strap from the trans to the body.
Long shot bit what have you got to lose?

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Gday Mudski,
Earth wiring is pretty good throughout, it seems to be isolated to just one circuit which has been confused. If it was a main earth point then I would imagine having more than one circuits worth of faults; having said that, you're dead right, what have I got to lose, already lost the hair [emoji17]

Thanks for the suggestions mate, I'll let you know how I go.

Cheers


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Is this an after market sensor or just the Dash one
from what I know the sender needs to match the gauge in Ohms ???

Hey mate,

Just the dash one. I reckon I'll fit an after market now but I still want to resolve the issue with this one. Noting it's tied into the computer, I don't want a false reading to make me go into limp mode.

Cheers,
Andrew


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A bad earth can do marvelous things.... Pre motor sway I had continuous issues with blowing two stop lights and my right rear indicator going haywire. I checked everything, added earth straps etc etc. Changed the motor over and all issues gone. Figure that one out. Lol.

Very very very true mate, even make the owner lose his shit [emoji16]


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I had all sorts of dash cluster issues and found the earth on the intake manifold was the culprit
Good starting point different year and engine model but if you go to the electrical section for your model then check the earth circuit you will find where the cluster gets its earth

Gday Kimbo,

Thanks for the reply mate, very much appreciated.

I'll give that bad boy a crack as well.

Cheers,
Andrew


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Mate I have the same model patrol and exactly the same problem. What I found with mine was if I turn the headlights on itd go up a little bit, high beams a little more and a/c on aswell and it would jump strait up to boiling. Especially when I'm on a bumpy road with no lights or anything on it'll jump strait up to boiling as well. The only thing I have found so far to temporarily fix it is tapping the cluster and if that doesn't work I have to pretty much punch the dash until it drops back down. It's defiantly an electrical issue. Mine is exactly the same, only the temp gauge plays up, everything else is normal. I have cleaned the main earth strap and didn't make a difference. If you find out a way to fix it let me know as mine has been doing it for nearly two years now!

Dpetersen,

Thanks for the detailed reply mate, I kinda feel a little bit better knowing I'm not the only one with this issue, yours sounds a fair bit worse than mine.

I'll be sure to let everyone know what I did if I manage to fix this bugger.

Cheers,
Andrew


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There are two coolant temp sensors. The two wire one is for the ECU and the single wire one is for the gauge. It sounds like you are checking the wrong sensor.

Going by your symptoms I doubt it's a faulty sensor. Possibly a short to ground in the wire that runs between the gauge and the sensor or a faulty gauge.

I would start by checking for signs of damage to the engine bay wire harness. Start at the temp sensor and follow the harness. Has any work recently been done to the engine?

Quote:

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Originally Posted by Yendor

There are two coolant temp sensors. The two wire one is for the ECU and the single wire one is for the gauge. It sounds like you are checking the wrong sensor.

Going by your symptoms I doubt it's a faulty sensor. Possibly a short to ground in the wire that runs between the gauge and the sensor or a faulty gauge.

I would start by checking for signs of damage to the engine bay wire harness. Start at the temp sensor and follow the harness. Has any work recently been done to the engine?

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G'day mate,

My sincerest thanks for the response, and it's got me excited to know that I've more than likely missed this bugger completely. I know where the sensor is with those two wires coming from the front of the block, but could you please tell me where the 'single wire' one is for the gauge please? A photo would be amazing if possible...

There hasn't been any work on the engine done lately, unfortunately due to work, it was actually the first time I've taken the truck out off the black top for a long time.

Thanks heaps in advance,
Andrew

This is the best I can do. Connector E235 is what you are after. Connector E219 is the one I think you were checking.

You could also try the old hit the top of the trick when it's playing up and see if this changes the reading.

Attachment 66436

AWESOME!!! Thanks mate. I'll give this a crack and let everyone know how it goes.


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G'day fellas,

After stuffing around with a disabled truck for three weeks trying to figure this bugger out, it's finally fixed!!!

My many thanks to everyone who contributed, and in particular, to Yendor for leading me on the right path for the final part of the problem.

I ended up having a few problems, including the dreaded flashing airbag light, but to help everyone up, when I finish putting the truck together I'll write up a bit of a cheat sheet with photos I took along the way to help the next poor bugger out with the same problem.

Cheers again,
Andrew

Quote:

---

Originally Posted by dpetersen

Mate I have the same model patrol and exactly the same problem. What I found with mine was if I turn the headlights on itd go up a little bit, high beams a little more and a/c on aswell and it would jump strait up to boiling. Especially when I'm on a bumpy road with no lights or anything on it'll jump strait up to boiling as well. The only thing I have found so far to temporarily fix it is tapping the cluster and if that doesn't work I have to pretty much punch the dash until it drops back down. It's defiantly an electrical issue. Mine is exactly the same, only the temp gauge plays up, everything else is normal. I have cleaned the main earth strap and didn't make a difference. If you find out a way to fix it let me know as mine has been doing it for nearly two years now!

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All your problems sound earth related as well. not sure on Patrols but on
Toyo's there was an earth strap for every section of the vehicle.
I just re-did one when I replaced the radiator, as Mudski says these Patrols
are famous for their earth issues, a few extra wont hurt lol

Quote:

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Originally Posted by rainman01

G'day fellas,

After stuffing around with a disabled truck for three weeks trying to figure this bugger out, it's finally fixed!!!

My many thanks to everyone who contributed, and in particular, to Yendor for leading me on the right path for the final part of the problem.

I ended up having a few problems, including the dreaded flashing airbag light, but to help everyone up, when I finish putting the truck together I'll write up a bit of a cheat sheet with photos I took along the way to help the next poor bugger out with the same problem.

Cheers again,
Andrew

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Hi Andrew,

I seem to be facing similar problems, any chance of getting the write up/photos?

Cheers

Phil

Gday Phil,

I haven't written everything up yet, I still intend to do so but the bugger has had a couple of hiccups since I thought I had it fixed.

I'm waiting right now for a new thermal transmitter to arrive which I'm 99% confident will fix the issue since I've already fixed the wiring.

Forgive the question, but do you have a multi-meter and the ability to check resistance along your wiring? I can lead you in the right direction as a short term fix.

Cheers,
Andrew


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Hi Andrew sorry i missed your reply. Yes i have a multimeter and can check resistance. My problem at the moment is that my temp will sit at high regularly sometimes it will show the engine is warm when i go to start the car in the morning. My main fuel gauge is also not working showing off the chart full most of the time. And my tacho doesn't work at all. Any help would be great as i have been battling this for ages, including new battery, extra earth straps etc.. Cheers Phil

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