ecm provides ground for the brown wire. check the ecm at the black c2 connector pin 27.

key off disconnect the c2 connector at the ecm, disconnect the ect connector. with a ohmmeter check for continuity for the brown wire from the ecm pin 27 to the ect brown wire connector pin. Should have 0 ohms. If its open, you could run a new wire.

I've wondered if you could run the brown wire to chassis ground; and the circuit would work? Would be easy to try and nothing lost.

 

Got 0 ohms testing for continuity. Going to try just grounding it the frame now.

 

Doing the exact same thing still with it grounded to the frame. I also left the coolant sensor unplugged completely, still did the same exact thing. Now what?

 

I must have overlooked something, I managed to get a p0117 code today.

 

Was the p0117 set by grounding the yellow wire to chassis or jumping the connector pins?

wondering if a bad wire is intermitantly affecting test results. Now that the wiring was disturbed the circuit may be working properly for now.

Is the code returning and the guage working with everything connected?

 

I cut the ground and 5 volt wire before the connector, attached them to get the p0117. I tested the ground at the connector but for some reason not the 5 volt side. Turns out it was the 5 volt side at the connector. Took a dremel to get the plastic out of the way and soldered in a new wire, everything works fine now. Thanks for the help, really appreciate it.

 

thanks for posting the fix