Hello,

I have a 97 F150 4.6 engine and am having some issues with the gauges. When I start the truck all the gauges are normal and after about 2 min the oil pressure gauge starts to creep up all the way to H. As soon as that occurs, the coolant temp gauge goes straight cold. After a bit the oil pressure gauge goes low and the coolant goes high.

The truck drives fine and does not enter into limp mode so it is electrical I believe. I have replaced the PCM, and the coolant temp sensor and the oil pressure sensor. No change at all. I remove the coolant temp sensor wire and all three other gauges work fine but no coolant temp.

I have heard it could be a GEM(removed that and looked at it no water damage or anything), the instrument cluster, or a grounding wire issue.

Has anyone ever experienced this or have any idea?

Thanks,

Jon

 

Jon, seems I have replied to this question in the recent past.
You just guessed at what you have already done.
.
In the dash panel assembly, the signals are received from the sensors, and processed by a solid state device 'in the dash', then displayed on the readout gages.
The PCM and GEM have no part in these specific functions except generate the information the sensors measure.
See the Haynes repair manual page 12-30, major and minor block diagram for this part of the dash system.
Good luck.