Grid Heaters not cycling after starting

[scotty-u]

This is the second time I noticed that after I started the 94 the grid heaters would not cycle like they normally do. The temperature was 27, and the truck had not run for 12+ hours. I cycled the key twice, as I thought the 'wait to start' message went out quicker than normal. After the second time, it started as normal, but the grid heaters did not cycle as indicated by the volt meter, or the decrease in RPMs as they turn on and off.

As stated before, this is the second time I noticed this. The next time I started the truck and ever since then, up until this morning, it has acted as it should. Can anyone explain why, or what to look for. Winter is here and the outdoor garage is closed for the season:-laf. Nothing has changed or been modified in the recent past.

 

[klcammie]

Possible IAT sensor going bad, loose connection or maybe a bad ground. Since it is a sometime thing I would start with the IAT connection also pull IAT and clean. Check the two small wires at the grid heaters. I had one that was loose had to squeeze it a little to make better connection

 

[sootnsmoke]

Did you get this fixed? If not, have you narrowed down the possible cause?

 

[CumminsPuller]

Resurrecting an old thread here....When cold out, my 97', with the key in the on position, the wait to start light does come on. You can see on the voltage gauge, the drop as the heaters are on. Once the light goes out and the truck is started, the heater never cycles again. After that, anytime during the rest of the day, they will cycle as they should upon startup.

Dirty IAT or connection? Other possibilities?

Jace