Dern Temp Gauge Stopped Working

[Stinky]

We just put a new PS Pump on my 86 720 and now the temp gage don't work to pretty good.  It doesn't move at all.

 

I checked the connection and wireing and didn't find anything that looked out of place.  The Sender is on the underside rear of the upper radiator outlet, correct, a double-plug deal?  

 

Would PS fluid kill the connection?

 

What sort of voltage should be on the line?  I looked at my fuse box cover and didn't see anything for gages on it.

 

What about a Fusible-Link?

 

What else?

[datzenmike]

To be a fusible link, half the fuse box would be dead also.

 

I believe about 8 volts in the line to temperature sender.

 

 

1/ The temperature and the gas gauges run off the same voltage regulator so look at the gas gauge. Is it working?

 

Yes the fuel gauge works... so the regulator is working, go to 2/ below

No the gas gauge does not work. The regulator behind the gauge cluster is not working

 

2/ Ground the two wires to the temp sender together with a small jumper. With the ignition on the temperature gauge should read full temperature. This shows that the gauge and the wiring is good. If still not working then replace the sender.

 

 

 

 

[Stinky]

Thank You.

 

Gas gage works.

[Stinky]

Jumping the 2 wires did nutN.

 

There was no voltage at the plug. In either wire.

 

I suppose that I should have looked for continuity while I was there.

[datzenmike]

One wire, probably black, is the ground.

 

Could be the gauge, as the power passes through the gauge out to the thermal sensor to ground. Might just be a poor contact. Wires don't just break in the harness.

 

 

[Thomas Perkins]

You know you have a temp.sender and a temp.sensor,maybe the wire to the sender came off when you was putting the power steering pump on.Pull both wiring off each and make sure they are clean.You can pull the sender out and clean the inside part with a scrub pad.Both of my plastic electrical connections dry rotted,on the sender,I used a male connector,and use this type on my sensor.Autozone has a lifetime warranty on both.My power steering bracket has a ground cable coming from the battery tray in which the negative battery connects to along with a smaller gauge black ground wire.The way Nissan did it.

Edited November 3, 2024 by Thomas Perkins

[datzenmike]

YES!! If you have the Z24i with throttle body injection there is a temperature sensor rather than a temperature sender for the gauge. I should have thought of that. It's directly grounded through the sender to ground on the intake. It's mounted near the gauge sender just under the thermostat and should have a Yellow/Black stripe wire. Unplug and hold the wire against the intake to ground it. Gauge should read full HOT.

 

Good catch Tommy!

[Stinky]

I have a carb and it came w.a carb

[datzenmike]

Yeah some have the ECC (electronically controlled carburetor) and it requires a coolant temperature input to the ECU to compute the primary jet solenoid rate. If you have a round 6 pin plug from the harness to the rear of the carburetor this is what you have.

[Stinky]

After seeing Thomas' pictures, I finally found the sender.  The plug was still there, but the wire was busted off.  It works now, but I don't know, the temp was low.  It was raining last night and it wouldn't get up to temp, which is believable as there woulda been a bunch of water on the road splashing up.

 

I have trouble getting up to operating temps in the winter.  I changed the T-stat, and the old one seemed fine....so cardboard it is.

[datzenmike]

The thermostat stets the minimum engine temperature. If there was over cooling from rain or road splash, when the engine gets down to the thermostat's rating it closes and will go no lower.

 

Over the years I have found that 'normal' engine temperature is about 1/2 way into the marked 'run range' and perhaps a needle width more.