Okay so after taking my 2005 F150 through the car wash my Temp gage starting acting up. It goes from the middle to the cold and then the check gages light comes on. Then after a couple of minutes it goes back to the middle. This again only started after washing the truck any ideas.

 

Sorry if this is posted several times first time on here. Back to my original question though. Could something have shorted out with the car wash? Would it go back to normal once it dried out?

 

Given the operational design of the engine coolant temperature (ECT) system, it seems doubtful to me. Unless water/soap could have gotten to the PCM through the cowling above the PCM plugs or wiring harness. Or if you washed the engine compartment.


If you are dealing with a 5.4L or 4.6, you have no coolant temperature sensor. The PCM calculates engine coolant temp based on the Cylinder Head Temp sensor, which is located UNDER the intake manifold on passenger side and not too susceptible to getting wet. The PCM calculates and sends the coolant temp, via a two conductor serial communication bus to the instrument cluster processor. THAT processor drives all the gauges on the instrument cluster.

CHT and calculated ECT values are available from the OBDII system if you have a code scanner capable of reading live data. That would help narrow it down to the CHT sensor or its wiring, or the Instrument cluster.


Good Luck