Engine/Transmission (1994 - 1998) Cold weather and Grid heaters

[BWilson]

Man was it cold this week!!! I have a question though, has anyone had the grid heaters cycle, at highway speeds, after the truck has run for over an hour????? It happenned to me a lot Wednesday, maybe 10 times. Can I chalk this up to kinda normal activity at these temps or do I have something about to break????



Thanks and have a great weekend!!



Brad

 

[ata]

I would say something is not right. The 97 Service Manual say`s they are suppose to shut off at 10 M. P. H. and I wouldn`t even have a guess why they did that.

 

[Extreme1]

The intake will get really cold when driving at highway speeds and the temp sensor will sense the low temp. I towed a trailer several hours in really cold temps last year and shut the truck off to unhitch when I got home. When I restarted the truck (about 2 minutes later) it went the through the heater cycle.



The PCM controls the heaters by the temp sensor and vehicle speed since being started. If your's is cycling at highway speed (and the speedo is working right) I'd guess that the PCM has issues. Check for codes. If it's the PCM and you didn't want to spend the money, you could put a switch on the wires to the primary wires to the heater relay which would allow you to turn it off.