Engine/Transmission (1998.5 - 2002) Manifold Heaters

[Claw231]

I have a friend that has a 2000 3500 and wants to know if there is a fuse or relay that controlls the manifold heaters. He thinks that they are not working. His truck is very hard to start unless it is plugged in. I only saw relays something like "engine control 1" and 2, diesel fuel heaters, that sort of thing, not one that said anything of manifold heater.



Thanks in advance for the help.

 

[B.G. Smith]

Heaters

The heaters are controlled by yhe Powertrain Control Module through two relays which are located just below the battery on the drivers side. bg

 

[illflem]

I've ran into a couple of rigs whose manifold heater problems were as simple as reattaching one of the smaller wires that slips over a screw stud on the relays below the battery. They were both way too loose, smashing them a bit with pliers before reattaching made for a better holding connection.

The large wire that leads from the battery to the relays is a fusable link, pretty obvious if it's melted.

 

[Claw231]

Thanks illflem, it was just a loose wire.

 

[Cooker]

illfelm,

On those trucks did the headlights still dim and voltage drop when the grids were engaged?

 

[Claw231]

The headlights do dim momentarily when the grid heaters cycle on, then get bright when they cycle off.

 

[Cooker]

Claw231, did they still dim when the wire was loose?

 

[B.G. Smith]

Diom

Originally posted by Cooker

Claw231, did they still dim when the wire was loose?

Not to butt in but if the heaters are not working, the lights should not dim unless there is a short circuit in the system, the heaters pull about 190 amps when on and even with the engine running that is more than the alternator can keep up with. bg

 

[illflem]

What BG said



I've gotten into the habit of checking the aforementioned wires on every rig that get under the hood of. Many are loose, a little pliers squeeze with it disconnected is good for peace of mind.

 

[Cooker]

Thanks. The reason I was asking is I have a friend who's truck is really hard to start when cold and he is not able to plug it in where he lives. He says the lights are dimming and voltage dropping so I assume the grids are working. He mentioned that sometimes there is a ton of white smoke so I am thinking maybe timing? It has only been cold here once so far but I would like to help him get it sorted out before it gets too cold.