I purchased a 97 1500 with a 5.2 (my first Chrysler product) a few months ago and am in the process of working through some issues with the truck.

In the process of replacing the stamped plenum plate with an aluminum one from Hughes I manage to break the coolant temperature sender for the gauge (the one wire sender). No problem, I ordered a new one from Rock Auto along with some other parts I needed. Anyway started the truck and the coolant temperature gauge needle went about half way between 200 and 260 degree marks. At first I thought the system was not circulating coolant. Finally I got the bright idea to check the coolant temperature with my code reader and it was 196 degrees F. Installed a new 195 degree thermostat during the manifold repair. With the original sender the gauge and the code reader read more or less the same. The new sender brand is a WVE. Since there was no sealant on threads used Loctite PST 592 for thread sealer.

I kind of doubt that it's an issue with poor contact between intake manifold and sender because according to service manual sender resistance goes down as temperature goes up. If contact between the manifold and the sender was poor the gauge would read too cold not too hot.

Have any of you had this issue?
Service manual has no specific information on sender resistance as it relates to temperature, any one know where that info might be found?
Any recommendations on sender brand?
Thanks,
Jeff

 

Replace the sensor. Don't use anything on the threads. Usually, they will come with some sealer on them, (depending on brand...) but, they are pipe threads, so, if it leaks, just tighten it up a bit more.

Standard Motor Products are generally good, genuine mopar sensor would be best, though, generally more expensive.

 

Page 14-53 in the '96 FSM has a resistance chart for different temperatures in case you want to verify the sensor. If you have some resistors at hand you can also check the gauge with the table.

 

Put a BWD in mine, it's off almost 30 degrees. Like Hey You said, Standard Motor Products or Mopar.

 

Hello-
I appreciate the replies, I checked out page 14-53 in the service manual, unfortunately that chart refers to the 2 wire sender that the PCM get it's information from. On this truck the gauge uses a separate 1 wire sender. Page 8E-29 has has resistance specs. All that's there is 361.7 ohms for low normal and 77 ohms for high normal. I have access to a gauge calibration tool that allows me to put a given amount of resistance in a circuit. Attached is a picture to show what I came up with.

Drawing of temperature gauge. Outside numbers are resistance (ohms ) needed to get gauge needle at that point.

While the needle is slightly high with 362 ohms it is where it should be with 77 ohms. The figures in between seem reasonable. I believe the gauge circuit is OK. Right now with engine coolant ~195 degrees F as indicated by the PCM the gauge needle is slightly over half way between the 200 degree mark and high normal mark. Will obtain a Standard Motor sender and install. Sorry about the sideways picture, do not know how to turn it. Thanks again for the input.
Jeff

 

Thought I would update.
I replaced the WVE sender with a Standard Motor Products sender. The Standard works the same as the WVE. Going to leave it for now. May obtain and install a Mopar sender in the future. I am concerned that the Mopar will work the same as the WVE and Standard senders.

 

Sorry the thread had fallen off my radar. Did you test the gauge from the connector at the sensor ? Also, did you check the resistance of the sensor itself, and does it read the same when measured to the engine block and to battery ground ? Does the reading correlate with the picture you created above, say engine temp is 195F according the PCM the resistance should be somewhere around 190 ohms.

 

The resistance values shown in my picture were generated by imputing resistance at the connector for the sender and grounding to the engine. I have not tried checking the resistance of the senders at operating temperature. Right now for me this is more of an irritation than a big problem. I know what the engine temperature is based on readings from the PCM. The truck is going to be parked for the winter shortly, I may pick this up in the spring. If I find a solution I will update the thread. Thanks for the reply.

 

Verify the temperature with a temp gun or something. The other sensor may be off a bit.

 

Did you use any thread sealer on the sender?