Coolant temp sensor

[ronnie4]

Well After my 1J swap my coolant temp gauge wont work. I double checked my wiring and it looks fine. When I put a multimeter between the terminal of the sensor and ground (battery terminal) I don't get a voltage or current reading at all, even when the motor is hot. Does this mean the sensor is bad? If so, anyone know any other cars that use the same one? I would think they are pretty standardized.

 

[suprahero]

I bought one for a MKIV and it fit perfectly. Their may be cheaper alternatives though. I think mine cost me 34.00. Good luck.

 

[ronnie4]

Just tried one from a 7M, worked fine by the way. Temp gauge still didn't work though. Does anyone know how the sensor sends it's signal? It is supposed to send voltage or current when it is warmed up?

 

[soapra]

Well After my 1J swap my coolant temp gauge wont work. I double checked my wiring and it looks fine. When I put a multimeter between the terminal of the sensor and ground (battery terminal) I don't get a voltage or current reading at all, even when the motor is hot. Does this mean the sensor is bad? If so, anyone know any other cars that use the same one? I would think they are pretty standardized.

The sensor has not voltage, it has resistance. As the sensor gets hotter the resistance changes and moves the gauge. The wiring goes to the gauge and it grounds thru the body harness connector where all the gauge wires come from. If that ground is not going to the right pin it wont work. Also if the car is a 89+ the Hydro fan ecu connector is the same as the body harness conector for the gauges. Double check all that and you should find your problem. Good luck.

 

[ronnie4]

That's awesome info, thanks

The sensor has not voltage, it has resistance. As the sensor gets hotter the resistance changes and moves the gauge. The wiring goes to the gauge and it grounds thru the body harness connector where all the gauge wires come from. If that ground is not going to the right pin it wont work. Also if the car is a 89+ the Hydro fan ecu connector is the same as the body harness conector for the gauges. Double check all that and you should find your problem. Good luck.

 

[soapra]

That's awesome info, thanks

Any time, any time. I hope you find the problem. :x:

 

[lagged]

Just tried one from a 7M, worked fine by the way. Temp gauge still didn't work though. Does anyone know how the sensor sends it's signal? It is supposed to send voltage or current when it is warmed up?

keep in mind that the sender for the gauge is a single wire, and then there is a second coolant temp sensor for the ECU which is two wire.

you need both!

 

[Cya]

Which motor set are you using? Im having trouble actually finding the wire for the temp sensor. Im wiring in a chaser swap.

 

[ronnie4]

Which motor set are you using? Im having trouble actually finding the wire for the temp sensor. Im wiring in a chaser swap.

It's a soarer motor, wire for the gauge is green/yellow. The two sensors are right next to each other on the exhause side of the head. If you having trouble locating the sensors I can post some pics tonight.

 

[myjz8u]

i have a standalone that doesn't wrok the gauge so to speak but my problem is when i connect the wire from the sensor to the cluster the gauge goes to hot and stays there what am i missing?

 

[zdatsupra]

I do not mean to hijack the thread but I have the same problem myjz8u describes and I do not want to clutter up the forum with the same subject. Can you Soapra explain better how the gauge grounds through the body harness? Where do you look to see how this is grounded?
When we switched over to using the megasquirt system we bypassed most of the stock ecu stuff. The stock ecu is still in place but now the temp gauge pegs hot and I am on the second sender.
Is it possible to add a ground to the temp gauge?

 

[aphxero]

grounds itself through the motor.

 

[suprastanger507mgte]

I do not mean to hijack the thread but I have the same problem myjz8u describes and I do not want to clutter up the forum with the same subject. Can you Soapra explain better how the gauge grounds through the body harness? Where do you look to see how this is grounded?
When we switched over to using the megasquirt system we bypassed most of the stock ecu stuff. The stock ecu is still in place but now the temp gauge pegs hot and I am on the second sender.
Is it possible to add a ground to the temp gauge?

If it pegs hot, you need to chack the cluster ground on the body plug od the M1 connector. Make sure it is connected. Also make sure the right sensor wire is connected (yellow/green)
Check you gauge itself.

 

[zdatsupra]

I checked the wire from the sender to the m1 connector.It is pin 9 on the connector.
I finally found that the ground wire was missing, it is pin 6 on the m1 connector.

Now after all this I have to see what happened to the fuel gauge that was working before I started messing with the temp gauge.
Thanks for the replies.

 

[myjz8u]

found the problem it was the cluster ground it was a brown wire connected it cluster works great thanks:eek3dance

 

[jmcboost]

Good Info!!!! I think I need to ground mine too. I'm having trouble with my temp gauge pegging out. I think this will work.

 

[ronnie4]

Did you guys just ground it to a metal piece near the cluster or tie it into the ground on the engine harness?

 

[jmcboost]

Yea!!!! It worked. I grounded the brown wire on that harness and my temp gauge reads normal now. I would say that as long as you have a good chassi groung that would work fine.

 

[myjz8u]

Did you guys just ground it to a metal piece near the cluster or tie it into the ground on the engine harness?

doesn't matter just find a good ground

 

[Cya]

Im having this problem as well. Time to find a good ground!