Temperature gauge needle jumping

[rainman01]

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

[mudski]

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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[rainman01]

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

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

Cheers


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[threedogs]

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

[rainman01]

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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[mudski]

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.

[rainman01]

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


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[Kimbo63]

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

[rainman01]

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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[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!