Grid heater test

[Mechanos]

In the Tech Manual for my 955, there is a detailed diagnois process for the engine air heater circuit and control module. If all of that checks out, the manual simply states "Check air heater" with no further instructions or info. I looked through the manual in several places and do not see any specs and info on checking the air heater itself.

I was hoping to find some resistance specs on it or some other way of checking it without having tear stuff apart. I guess there may be a chance that I can remove the air inlet hose and may be able to see the heater element to check it.

 

[beenthere]

Interesting.
What is a "grid heater" ?

Is it the same as the engine air heater?

 

[Mechanos]

Interesting.
What is a "grid heater" ?

Is it the same as the engine air heater?

Yes.

Sorry. I've been driving and working on a Cummins powered pickup too long I guess. That's what Cummins calls them.

 

[KWentling]

I would think as long as it isn't open that it is good. I don't know what the resistance should be but I would think that they would burn in two and be open when failed.

Kim

 

[kennyd]

I would suspect you should have near zero resistance if checked with a ohm meter, that's the way glow plugs are. I can't believe they dont put a value in the manual but one things for sure, if it's open (infinite resistance) then it for sure won't work.

 

[JD755]

While nothing in the 955 manual, the 4x00 tractors use similar or same device. That manual shows 0.3 to 0.5 ohms. So like Kenny said, near zero ohms.

 

[KWentling]

I never had the chance to look at one, but if the germ "grid" is used, does it vaguely resemble a window screen? If so, is it possible for only part of it to burn up?

Think "like the grid in a toaster". I'm pretty sure it is one long element bent in a back and forth pattern.

I looked in my Dodge service manual and it says resistance should be zero or near zero.


Kim

 

[Mechanos]

As suspected, the easiest way for me to check it was to removed the air inlet hose and just look down the neck. It actually looks more like a ribbon about an inch wide, standing on edge and folded back and forth many times. A jumper wire from the postive battery terminal to the heater stud was all that was needed.... the heater glows bright yellow-orange. My control module, however is toast.