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How does the water temp gauge work on our cars? Is it just a single wire going straight to the gauge?

After I spliced my standalone in, my temp gauge has been reading full hot all the time after it warms up. I know for sure its still running 180-190 by plugging in my lap top and checking the CTS via standalone software.

This accured the moment I installed the new ECU.

Is there some way to rewire the sensor?

Water temperature is sent to the ECU and the gauge cluster by 2 different wires.

The wire going to the gauge cluster is just a single wire that taps into the coolant crossover pipe, and has nothing to do with the ECU.

The wire going to the ECU is the coolant temp sensor which is a 2 wire which sends resistance readings to the ECU to adjust idle and tell the ECU when to run the cooling fans.

Which one did you tap into?

Jessekrs123 wrote:Which one did you tap into?

Based on his post I'd say he tapped into the single wire (wrong one).

I left the single wire sensor...the gauge one alone. The CTS 2 wire one I spliced to the standalone and recalibrated to read properly. The CTS is working fine. After the install, the gauge started to read fully hot. I think there might be a shared ground somewhere in the harness that is causing the issue.

All I need to know is how the temp gauge sensor works and is wired.

probably need a diode in there somewhere to keep the sensor from grounding through the new ecu wire. I'd try to put a diode between the "new" wire and the gauge wire with the band facing the gauge.

Sounds like you have a sensor ground for the stand alone shared somewhere that you need to fix. When I installed my link I did not have any issues with the dash gauge.

How do you have the stand alone hooked up to the two-wire CTS? You should have the stand alone supplying +5v to one pin of the sensor, and then the other pin on the sensor should go to the analog input for whatever input you're using for the engine temp.

Here's a diagram for the dash temp gauge. It's for the Liberty, but gives you the idea.
http://www.main.experiencetherave.com/s ... n-USDM.zip

I spliced the Pin 7 on connector E2 (main engine connector) with the coolant (connector B) on the Haltech....this must be the 5v supply

Pin 11 on connector E2 was spliced to the Signal Ground on the Haltech

I left the gauge thermometer wire untouched

Unless you are calling the pin numbers different, you connected them to the wrong pins. They should be connected to pins 5 & 6 of F26, which plugs into E2. The FSM almost always lists the pin numbers for the male connector.

Pin 5 is what you want to hook your 5v supply up to. Pin 6 is the reference sensor ground which needs to be separate from the chassis ground.

If you haven't done so, get the factory manual from my server. It should help with the wiring.

I was thinking of running a fresh wire from the thermometer sensor to the temp gauge.