Engine/Transmission (1994 - 1998) Grid heater problems

[RStankevitz]

Ok i have a 96 with the ctd and my grid heaters arent working. in the am when it was -5 F i went to start truck and no grid heaters. the wait to start light comes on but stays on for a short cycle more like i am used to seeing in the summer. now i checked and both relays appear to be fine but i haven't bean able to check them first thing in the am? also after the truck has been run if you shut it down and restart it the grid heaters work like normal?

Any ideas what to tackle first? i do have a new air temperature sensor for the intake i will install tomorrow after i get the truck back. it is at the transmission shop getting a new transmission and bd torque converter etc Oo.

 

[EKlem]

I would start by simply unplugging the intake air temperature sensor and trying to start it. If I remember correctly, the resistance goes up as temperature goes down so providing an open circuit should give you the longest cycle allowed. I have run my truck with the sensor unplugged before. I think this would be a good place to start just because you can do the test in about 1 minute.

 

[RStankevitz]

ok i will try that and post back

 

[JFaughn]

Use a test lite to see if the relays are getting a signal to turn on .

 

[RStankevitz]

ok this am 5 deg f i tried and no grid heaters so i unplugged the air temp sensor and they worked. now this is a new air temp sensor i changed it 2 days ago. the replacement is a standard brand from auto parts? so monday i will call the stealership and get a dodge/cummins part? but it has to be the sensor right?

 

[EKlem]

It sounds like the air temp sensor to me but it is not out of the question that the parameters in the pcm are messed up.

 

[DieselDoghouse]

Scan the PCM for soft codes stored with the change in sensor?? Mebbe?

 

[RStankevitz]

well there was a air temp sensor code but i think thats from where i started it with it unplugged and my trany guy cleared them if the new sensor doesn't do it i guess it is in to the diesel shop for the ol girl