Dash temp gauge not working

[s1de_ways]

So iv just installed a Haltech E11 to replace my old Wolf. The problem i have is the temp gauge sits on High until i put my foot on the accelerator then it drops to low.

The temp sensor that goes back to the ECU is correct and the Haltech is seeing the right temp.

What i need to know is where does the dash gauge get its signal from?the probe from the thermostat goes straight to the ECU in the loom.

Im assuming the Wolf sent a signal out to the gauge and the wires been cut under the dash but i cant find it.Any ideas?

Its a 94 GSR running a 6 bolt 4G63 if that helps.

 

[EVO-00X]

If you're using a Haltech plug and play patch loom for an EVO I-III then there should be no issue with the temp reading. Was the Wolf spliced into the factory loom? if so looks like when it was removed something has been crossed over. The temp sensor in the cluster gets its feed from the factory interior loom going to the ECU.

 

[s1de_ways]

Yeah the Wolf was spliced in but i cant find where. Can i cut the wire feeding the gauge and splice into the probe coming back to the ECU or would that not work?

 

[EVO-00X]

Not sure about that way, depends how the signal is sent to the ECU and how the ECU sends the signal to the cluster. It may or may not use the same voltages/signals.
When you're in the Haltech Halwin software does the software pickup the engine temperature? If so thats a good start and the problem isnt from the engine bay to the ECU.

I would then get the EVO I-III ECU pinout drawing in the tech sticky's section and look for the pin number corresponding to the water temp sensor, which actually is ECU pin#63 a yellow wire with green trace (in the 3 x OEM yellow ECU plugs). Then I would remove the gauges cluster and look at the back of it and trace the foil in the flexible circuit board which leads to the temp gauge. Follow the foil all the way to where the brown and blue plugs plug into the back of the cluster. Take note of the position. Then look for the corresponding wire going to that foil in either the blue plug or the brown plug. When you find it, run a multimeter between the factory yellow ECU plug pin#63 (yellow wire with green trace) to the corresponding wire on the blue or brown plug behind the cluster. Check for a voltage reading on the wire to make sure power is getting from the ECU to the cluster with acessories turned off (to make sure wire isnt cut). If you get a signal then all good and you've got the same wire. Then turn accessories on and see if something happens to the reading on the multimeter (in case it is earthed out somewhere).

Let me know if you didnt understand what I wrote as eletrical issues are a lot easier to faultfind in person than to explain in words lol

 

[philsth]

There are 2 temperature sensors, one that the ECU uses and one the Temp gauge uses.
Pin 63 is the sensor the ECU uses and doesn't have any input to the gauge.
The other temp sensor goes directly to the temp gauge, it works by varying the resistance to earth as the water heats up which changes the current flow through the gauge causing it to read higher.

It is strange that fitting the ECU has effected your gauge operation as it doesn't use the ECU.
If it sits on High then its very likely that it's earthing out but why it goes low when you hit the accelerator is WTF :huh:
I'm not sure of the locations of the sensors on the 4G63 as I have a 4G93.

Not sure if this helps but it gives you a bit more info.

 

[s1de_ways]

The haltec software is getting the signal alright. The gauge wire is a Yellow with red trace. Philsth that makes sense.the Wolf was wierdly wired so they must have got the temp signal off the gauge probe. As soon as i can find that ill just run a new wire to it from the gauge. Anyone know where it is?

 

[s1de_ways]

Found the other temp probe.Ran another wire to it and it solved the problem. Cheers for the help.