Hi guys, 

got the new grid heater battery jumper wire set I had ordered.  I put it on, tried it and fried it in 5 seconds- bye bye $40. Anyway, I just followed the troubleshooting instructions here after this disaster:

 

 http://dodgeram.org/tech/dsl/troubleshooting/Maniford_htr.htm

 

I have .1 or 0 Ohms (depending on the multimeter setting) across the heater grid terminals as stated in the 2002 instructions. But it seems like you wouldn't want 0 if going from the grid terminals to ground as that would in indicate a direct short to ground.

 

If I jump the grid straight to the battery its like a welder. Anyone have any issues with this before? I took the intake horn off just to check if something was sitting on the grid and it's clear.  Im not sure what could be grounding out. I also checked the heavy relay to grid wires and they are fine.  

I'm out of ideas and its 10F today and high of 1 and 3 F this week.

 

Thanks

 

First of all is it one or both? If it is one then I would look real close at the insulating bushing where the stud comes out. If it is both then I would pull the intake horn and go from there, but remember, they do pull about 90 or so amps each and a lot of welding is done at lower amperage.

It melted the new wire in 3 seconds, so its getting way too much power. Hard to say if one or both because I get the same readings.  Are the bushings a problem?

It melted the new wire in 3 seconds, so its getting way too much power. Hard to say if one or both because I get the same readings.  Are the bushings a problem?

I have not heard of many problems with the bushings. Something else you can do is pull the heater elements out to look at things better too.

edit: I found a video that shows the grids pull about 75Amps MAX. http://www.youtube.com/watch?v=LQONNwYr2ks

Edited January 26, 201411 yr by MnTom

I just pulled the relay set and checked them, No shorts or visible arc damage to speak of.  I put 12v to each side and they opened and closed normally.  I guess it has to be the heater itself- there is no other possibility I can see. I do see a NAPA part # CRB265000 for $161 and a mopar Part # 5086720AC for $130 from dodgepart.net (Berry Dodge, TX). Guess I'll order one up unless someone has another idea. 

AP

Before you order one up take a bit of time and examine your heaters. They are really simple in design and about the only place I can think of is either the stud(s) are shorted or MAYBE there is something shorting the grid when it is put together. I have not ever heard of anyone needing to replace the grids.

Thanks MnTom

I'm going to check it again, The new fusible link burned in seconds , all wires check out, no direct ground paths. Only thing I can figure is the heater itself. 

Edited January 26, 201411 yr by AGPTurbo

Ok, Just for S's & G's, I pulled the air horn again, and took some high quality jumper cables and hooked them direct- battery to grid heater.  It never glowed, just made my jumper cables smoke lol.  I guess this thing i shorted internally.  I'll post the results of the NAPA trip tomorrow.

AP

Edited January 27, 201411 yr by AGPTurbo

Again, they are so simple that about the only thing it could be is the insulating bushing(s) broken.Pull the other nut and check them.

If the relay was not energized, & no shorts in the wiring, it has to be the stud. Is it 1 or both that do it?

I would see no problem putting used grids in & you can get them from southerners that think that they are losing massive amounts of airflow to them.

 

Ed

Got the new grid today from Bridgeway Cummins in Pittsburgh.  Cummins # 3969987 $99.55, (great price) Also 2 metal style intake gaskets PN 3969988 , 4.42 ea. I couldn't get a replacement from Rock Auto under 115 plus shipping. Swapped out, works perfect.  The old one had both grids hard shorted. I disassembled and all seemed normal, tested on the ground with jumper cables, did the same thing, hello scrap pile!.  For the $99, I wouldn't waste my time with used junk, especially since this one lasted 100K. Also, I tested the old vs. new with a multimeter- old read 0 ohms, new one reads 3-5 in case anyone ever gets in a similar jam. 

Thanks for the replies.

AP

Glad you got it fixed! Plus it was a simple fix!!