Chrysler Repair: P0128/ P2181 Temp Gauge Prob.

Question
QUESTION: Hi Roland

You've helped me in the past and i need your assistance again.

I have a 2008 Town and Country Van, 3.3 L Vin H flex fuel.
Cel on, codes P0128 and P2181.
Has good heat but does take awhile to get hot.
Temperature Gauge on dash barely comes off of the Cold mark,maybe an 1/8 of an inch off C
Replaced the Thermostat, still the same gauge reading.
Van starts and runs fine, has good heat

I'm thinking its a bad Engine coolant Temperature sensor.

Aftermarket sensors are cheap but not sure if i should go with that or the $38.00 Oem one.
or is this something other than that
any help is appreciated

Thanks

Joe

ANSWER: Hi Joe,
Other than the thermostat or low coolant level both those codes point toward the ect, either in its circuitry or the sensor itself. So examine the harness wires to the sensor for any signs of damage. If none are found then you can either do a check of the wiring using a volt-ohm meter or by-pass that and get a new sensor. The sensor is a simple device so I don't believe that an oem is necessary if the aftermarket is much less expensive. Let me know if you want to trace the 2 wires from the sensor to the pcm and I can give you the pin assignments.
Please read the PS below and respond to it.
Thanks,
Roland

---------- FOLLOW-UP ----------

QUESTION: Hi Roland

Thanks for the fast response.
I'll go with the aftermarket then and see what happens.

Quick question.....

I was told by someone to disconnect the wiring connector at the ECT and use a jumper wire to connect both terminals together and see if the gauge reads hot....
Can i do this or will i ruin the PCM?

Thanks
Joe

Answer
The ect has a resistance of around 4,000 ohms when cold, and as it heats up its resistance drops below 1,000 ohms. I doubt it would do damage to do a jump with a wire, but better would be to buy a resistor of around 1,000 ohms at an electronics store and jump that across to see if the gauge then reads about 3/4 to full scale.
Roland