1987 coolant temp gauge needle bouncing.

[rab]

1st off the truck is a 83 2wd ranger, i swapped in a 2.3 turbo from a 87 xr4ti.
Recently i swapped in a 87 ranger tach cluster also.

The coolant temp gauge needle is just vibrating at a fast rate on the lower end of the temp i.e. cold.

Now I'm almost 100% positive i repined the new tach cluster gauge correctly as everything works correctly as it would if it was a stock piece.
I can't remember but i assume the coolant temp SENSOR for the gauge (i.e. the one on the engine is from the xr4ti and not the 83 ranger)

I know ford had some different sensors for dummy lights clusters compared to clusters with actual gauges in the 80s. Im not sure if thats the case or not.

So do think the actual gauge on the cluster is bad,the sensor on the engine is bad,the sensor on the engine is incorrect or something else?

Also i never really had the stock 83 cluster hooked up or looked at it much since i did the 2.3 turbo swap,so I'm not sure if it worked with the stock 83 cluster and i don't drive the truck much as its kind of my low budget spare project as i have other projects going on too.

 

[RonD]

Temp gauge uses a SENDER, it only has 1 wire hooked up, like oil pressure sender.
Sensors have at least 2 wires, just FYI.

Easy to test if it is the gauge/wire or the sender that is the issue.

Find the sender, it will only have 1 wire hooked up.
1987 2.3l it should be on the thermostat housing or very near it.

Remove that 1 wire
Turn on the key
Temp gauge should either show full HOT or full COLD now
Use a jumper wire and Ground that 1 wire to Battery negative or any good ground on engine.
Temp gauge should now show opposite of what it was before, if it was full HOT, then it will now be full COLD, or visa versa.

If gauge needle doesn't work then wiring or gauge issue, if it does work as described then replace the sender.


Fuel injected engines have an ECT(engine coolant temp) sensor, these are only used by the computer and have 2 wires.

Some also have CHT(cylinder head temp) sensor also only used by the computer, and 2 wires.

 

[rab]

Great way of putting it, thanks i will try that.
side note i think my coolant temp sensor for the gauge cluster is on the backside of the intake somewhere by the oil cooler on my 2.3 turbo motor.

 

[RonD]

Could be, I know on some 2.3l if was not near the thermostat, so would always read cooler than it should.

But 1 wire hook up is what to look for a sender