My latest 2nd Gen electrical system gremlin
 

I walked out to my truck yesterday and, as I usually do, pressed the unlock button on my factory remote. Not hearing any sound at all, I repeated the operation, to no avail. After hearing the old "Uh, oh" in the back of my mind, I used the key to unlock the driver's door—only to find a dead zone within. "Did I leave one of the overhead lights on?," I thought.

So I opened the suicide doors and pulled the required tools out for a battery removal [the place we live in won't allow me to run an extension cord out for a charger]. As I did my normal visual inspection, I noticed that the aluminum air intake inlet connected to the top of the preheater coil block was discolored (darkest just above the grid block). Upon further inspection, I noticed that one of the boots covering one of the electrical connections to said preheater coil was burned beyond recognition.

Judging by what I saw, I must assume that my truck's psycho ECM decided to energize the preheater until the batteries were totally drained. This happened while the truck was parked for the night, so it's just another crazy signal sent my ECM (I guess). By the way, this isn't the first time something like this has happened. Once, the truck alarm woke everyone in the complex up in the middle of the night and, on another occasion, I had an open fire under the driver's seat while I was troubleshooting an engine run-on issue ... speaking for my truck, the electrical system leaves much to be desired.

If anyone out there with a 2nd Gen CTD Ram can clue me in on what's included in the Ram preheater circuit, I’d be much obliged. I've already disconnected the wiring harness running to the preheater coil block, but I have no way of knowing what else might drain the batteries in this particular circuit. In other words, I don't want to end up with dead batteries again because something else in the preheater circuit is continually energized.

Thanks very much for your time,
B&W
:c:

if you didn't have all the other problems, it would be the grid solenoids that are sticking on. i'd still probably start checking that first. but all the other problems--yikes!

the ecm on these truck have many issues i would recommend get a new updated on with all the bugs worked out of it. you can get them from a company based out of florida with a life time warreny for under 600 buck last i checked i think mine was 495 for my 99 2-3 years ago dont remember when exactly i changed it. the name of the company is, auto computer exchange, 954-983-4948, they are in Fort Lauderdale. they are good to deal with. i agree with the solenoids sticking on but something had to cause them to stick and the ecm controls that. youve probably killed the heater element too with a discharge like that. so i would replace both solenoids and the grid aswell as the main wires feeding them. and i would really look into a ecm preventative mant will go a long way, who knows next time it may cause a fire and burn the truck to the gound. if you didnt live in a cold climate i would say just delete the thing and all the wiring for it. thats what i did.

I was aware of two separate intake heater relays -- one for each element -- but this is the first time I've read about "grid solenoids." Can you tell me where they're located?

I've since reinstalled the batteries, taped up the intake heater leads/terminals and secured the supply harness to the plastic dipstick cover. As far as I know, the intake heater elements are the only loads in the intake heater circuit, so disconnecting the wiring from the heater block should prevent the batteries from being discharged again. I guess we'll see in the morning.

As for changing the ECM, that seems pretty interesting. Did you get a modified harness with the new ECM? Why did you change the ECM on your '99, BanditsDiesel?

Have a good one,
B&W

i had same problem on my 01. it never gets cold here so i just took of main lead to solinoids. i always figure in a emergencey i could hook back up, well im to cheap to buy new cylinoids, and they are a pain to change.

it was just the module. and my heaters wouldnt work some of the eletronics came and went. no harness. try to access the ecm with a tunner and have to do a recovery mode on the truck

the solenoids are the relays. some say they are undersized for the application, and get fatigued and cause the failure you had.

On the left hand fender, below the battery. :tu:

If anyone out there with a 2nd Gen CTD Ram can clue me in on what's included in the Ram preheater circuit, I’d be much obliged.

I will try to attach a file that will provide you the entire circuit for the heaters. I would also recommend you check the 40-AMP slow-blow #7 fuse in your engine compartment as that should have controlled those relays. In theory, it should have burnt the element due to the power consumption the heater took for such a long perios of time. Either the fuse itself is higher than the factory 40-AMP or ???. Good luck!!

Thanks for the posts I've been getting so far, fellas. :tu:

x2be1: The viewer I'm using to see your drawing doesn't magnify it enough to be of much use. Can you PM me with your email address so that we can correspond about this? Looks like a very nice schematic.

Please keep 'em coming
:c: