grid/manifold heater/preheater

[LittleSmoker]

Just recently got back after a 19,000 mile trip, pulling my 5th wheel. After cleaning up the truck (under the hood also), my "wait to start" light does not stay on any longer than the rest of the dash display when starting. Also, the amp gauge does not cycle to indicate that the heater came on at all. Any suggestions as to how to trouble-shoot this? Hopefully it will be something easy like a blown fuse. Haven't located a bad fuse yet.

 

[klenger]

The heater is not used if the temperature is above 63 degrees F (I think that's the correct temp). I think that the owner's manual mentions how it works.

 

[LittleSmoker]

To Klenger, Thanks for the reply, but I was aware of the minimum temp. for the heater to come on. Unfortunately, the light doesn't stay on even if the temperature is in the 50's. Any other ideas would be really helpful. Anybody have a problem with the relay switches that are mounted below the fuse box on the left fender well?

 

[illflem]

The heaters on my '95s don't come on till about 50°

 

[Diesel Freak]

you could make it fully manual... I disconnectrd my grid heaters from the ECM, and now I have a momentary switch on the dash to operate them when I want to

 

[Missouri Mule]

Lil' Smoker,



Yes some members have had trouble with the heater relays. Most of the time when they are going bad they tend to leave the grid heaters on to long.



I would check out the manifold tempature sensor to make sure it is reading tempatures right and that is at the correct resistance for the tempature inside of intake manifold.



Sometimes the intake mainfold will stay warm (Above 59 degress, this is temp the heater grid will normally activate. ) enough that the grid heaters will not turn on. So wait to start light will not be activated.

But if the air being pulled into intake manifold is below 59 degrees after engine is started the IMTS/PCM will turn on the grid heaters on in an on/off cycle or until truck reaches a preprogrammed MPH.



Your PCM turns on and off the grid heaters thru the relays. Your PCM decides if heaters need to be turned on thru the data (resistance) the intake manifold tempature sensor sends to it.

 

[ABailey]

Originally posted by Diesel Freak

you could make it fully manual... I disconnectrd my grid heaters from the ECM, and now I have a momentary switch on the dash to operate them when I want to

Diesel Freak:



Can you elaborate on how exactly you did this? I want

to do this too but I don't know where to start. Thanks

for any input you can provide.

 

[Diesel Freak]

well, I just disconnected the trigger wires to the solenoids, and installed a momentary switch I purchaced from Radio Shack and mounted the switch in the dash. I used a permanently hot lead from the fuse box in the engine compartment along with a two amp in line fuse to give the switch and trigger side of the relays power... then I grounded it to the frame. I am not at work, so I cant draw you up a basic schematic... . I will post one by thursday.







PDX? if you are in Portland, I could just show you.