can't figure it out replaced everything.....

[Tbarnes93]

I have a 1994 ford ranger 4.0. I have replaced about everything i can think of coolant wise. new radiator, water pump, all new hoses, thermostat, radiator cap and even coolant temp sensor.( broke it replacing head gasket) I cant get the temperature gauge to work. it stays on cold even after the thermostat opens. The first coolant temp was faulty and threw a check engine light so i took it back and bought the more expensive one and this time it didn't throw a light but gauge isn't budging off cold. when i turn it off the gauge will rise a little bit but when i turn the key back on it goes back to being buried. i cant figure out what the issue is and i need my temp gauge working seeing how i just replaced the head gaskets. I have tried about everything i can think of so if you guys have any ideas it will be greatly appreciated. I have had nothing but trouble out of this truck..... thanks.

 

[Tbarnes93]

the gauge was working before we broke it btw.

 

[RonD]

The dash temp gauge uses a 1 wire sender on the intake, it is a simple resistance sender.

To check the wire and gauge remove the connector on the sender, turn on the key, gauge should be all the way UP or all the way DOWN, doesn't matter which but all the way.
Now ground that connector wire, short wire to the Negative on the battery is fine, gauge should now do the opposite of above, all the way UP or all the way DOWN.

If gauge does this then wire and gauge are fine, replace sender.
If gauge doesn't go UP and DOWN then you will need to trace the wire and maybe pull the dash.


The temp sender should not be confused with the ECT sensor, the ECT sensor has two wires and is only used by the computer, it is unrelated to the dash temp gauge.
They look similar but are not the same.
A faulty temp sender will not turn on the check engine light(CEL), only the ECT sensor would if there was a problem.

Also on any 1 wire senders, the threads are part of the circuit, so do not use sealing tape on the lower threads, it needs a good ground via the threads.

 

[ab_slack]

^^ What Ron said. It's a different sensor than the one you replaced. If it was working before all the engine work perhaps it got disconnected.

 

[Tbarnes93]

okay i will look at it in the morning i may have forgot to connect it back after i took everything apart.