I posted on this a while back, but it appears to be gone.

My headlights will intermittently dim when driving down the road, or when sitting still. I thought it was the multi-function switch as someone on here suggested, but a new one made no difference.

The truck has no problem starting ar anything like that, but I have noticed when the headlights dim, the charge meter also drops significantly. I also have a windshield wiper that wont park itself if you switch it off in mid stroke, and the key fobs don't seem to always work. I mention these, because I am not sure if they may be related or not.

The issues occur with or without the trailer being hooked up, and the headlight thing definitely seems to be worse after you have been driving for awhile. I have noticed the charge meter doesn't hardly drop at all unless the headlights are on, but it does drop from time to time.

For some reason, I am beginning to think I need a new computer....

How would one go about testing the alt since the grid heaters will come on if you aren't going fast enough ? start the truck then disc them ??

any ideas on what's going on here ??

 

Grid Heaters
cookie

 

nope...not grid heaters.....unless they come an at 70 mph, and in a sporadic fashion

and the charge meter drops MORE than it does when the grid heaters are on

 

I would disable them to be sure. Sometimes mine will come on sporeradicaly at diferent times and speeds. Check intake air temp sensor if its bad they can come on anytime.

 

Ok, I went and had them check the alt tonight.

1st time, with grid heaters connected, 13.89 v, 128 amp

2nd time, no grid heaters, 13.89 v, 143 amp

left and started home, gen light comes on and doesn't go off. turn around

3rd time w/ gen light still on & grid heaters connected, 12.88 v 201 amp

turned engine off, and back on, gen light went out


4th time with gen light off and grid heaters connected, 12.88 v, 183 amp



any clue as to what's going on here ????? lights still dim with grid heaters disconnected

Keep in mind this is a 120 amp rated alternator

 

i did notice you mentioned the key fobs don't allways work. posible bad ctu?

 

that's what I'm thinking...or should I say fearing

 

how about a floating short or ground in one of the batteries?

 

both batteries check out good

any more ideas guys...this is getting to be a PITA

 

Whatever you do, don't go to the dealer there in NN. They ripped my wife off big time.

You have a dead short somewhere, a loose wire, a chafed wire, something like that. It is normal for the alternator to drop off line if the draw is more than it can handle. I have my grid heaters wired to a toggle switch and if I forget to turn them off or the switch gets turned on by accident the alt quits soon after. I have to shut it off, wait a few seconds, then restart it. This has happened about a dozen times over the last 4 years and the alt has always come back on line.

Chasing wires is a PITA, especially when it is intermittant, but I don't think throwing parts at it will help. We have a PCM. What is a CTU?

 

I don't know...ask biododge

That's why I am checking everything I can to avoid throwing money at it....

I may take it to a local electrical shop and see what they can find.

I got a hookup at the dodge dealers around here.....

 

Shucks, thought I might learn something. Good luck.

Just thought of something. Look for a large wire, something akin to the size going to the grids. A smaller wire grounding out will burn in two if a fuse don't blow. When you checked the grid wires did you disconnect both ends? Carefully inspect the hot leads to the battery and it wouldn't hurt to disconnect and clean the terminals at both ends of the ground wires.

 

I disconnected both grid wires, but not both ends of each grid wire.

I am gonna check the ground wires real good tomorrow

the 200 amps scares me...you can weld 1/2" thick steel with that

 

OK, time for an update.

Still have the problem.

I checked the grid heater tonight, and the FSM says if it reads anything other than 0 ohms when checking from the post to ground, to replace it. It reads 0.4 ohms with the grodun being less than 4" away. I also noticed the posts for the grid heater never tighten up. I'm thinking this is part of the problem, as it would not get a good connection when the heaters come on.

I checked the temp sensor. For the outside air temp, it should have read in the 15k ohms range, but it read 11k ohms...not sure if that is a problem or not. Seems to me it just means the grid heaters won't come on as much as they should.

I checked the relays per the FSM, and both of them seem to work fine with no sticking evident.

Now, if I have the grid heaters hooked up, the charge meter is not steady at all, and varies from 12.2 - 13.9 v. If I disconnect the grid heaters, the charge meter stays pretty steady at 13.9-14.0 v.


I am supposed to make a long trip this weekend to move a truck for someone and pick up some parts for myself.

I kinda need some input on this now.

No MIL fault codes either BTW.

Any ideas ? All this testing was done sitting in the driveway, so the grid heaters may have been cycling off and on, but there was no pattern to it at all.

 

You surely have a problem with the grid heaters system somewhere . I would completly disconect both make my trip and between now and next winter troubleshoot the entire grid system wires grounds and whatever activates them.