need help! ECM??

[dieseldon]

So, went camping with son this weekend and his 98.5 had some problems we're trying to figure out.

Went for a short drive and smelled smoke, turned off truck and looked under hood, alternator was smoking!

Alternator was hot as hell!

Fidled around a bit with the connector coming out of it and he thought they were possibly touching each other? One definitely was showing bare wire at connector.

Any how, after messing with those wires he turned truck back on and alternator seemed operate at least cool to touch , problem is now no WTS lamp and grid heater not working. We did get it started in morning but below freezing and it wasn't happy! Didn't think about it at the time but probably no fuel pump either. He has a mechanical belt driven one or probably would have been stuck in the middle of nowhere!

 We're back in town now trying to figure out, reading threw forums and what not, sounds like possible ecm issue? Bad ground somewhere? Alternator took out ecm?

Son just updating me:

 He states before trip something was draining his new batteries, Now say's he just unplugged ecm to inspect connector, plugged back in and reset apps, now WTS lamp coming on and grid heater works!? Say's WTS is a little delayed.

 Question, what all does the ecm operate? Since he does have the mechanical pump can he rig something up to manually turn on the grid heater if in fact the ecm is dying? Is there a way to actually test the ecm?, (We're both

electrically challenged)

 I did the wt ground mod on his a while ago but never checked ac noise before or after, not positive how to do that, need to check mine too!

I know, he needs to get on here and join forum too!

Sorry for the long post! Thanks for reading.

 

 Any suggestions or help would be greatly appreciated!

Alternator? Grounds? Ecm going out? All the above??

         Thanks!

 

 

 

[IBMobile]

@JAG1had something like that happen to him not long ago.   I think it was a shorted cell in one of his batteries.

[dieseldon]

1 minute ago, IBMobile said:

@JAG1had something like that happen to him not long ago.   I think it was a shorted cell in one of his batteries.

Brand new batteries, seems unlikely?
 Thanks for suggestion!

 

 

[dieseldon]

Not sure if this update means anything?

He says he got a little shock last time he touched the alternator bracket.

 Maybe the bracket needs a ground?

 

 Does anyone have a good link to the alternator ac test, (with cheap dvm?)

Were to set dial, what to disconnect, with pictures,etc. ??

Or should we just pull and have tested?

Just hate to have someone do something I should know how to do by now.

Here's my dvm, not sure what settings to use or how/ were to test.

 

If I'm guessing, set it to this? Hz mv, ac?

Are we looking for volts or amps?

Did I mention I'm electrically challenged??

 

 

    Thanks for any help!

[Dieselfuture]

Set it to vac, it needs to be 0.03 or less 0.05 is on the edge. Test it on the alternator stud red lead and body of alternator black lead. Pcm control alternator not ecm, sounds like you may have did some damage to ecm because of high ac voltage coming from alternator. Ac volts should be minimal, diodes make ac go to dc, cuts the wave in half basically. Not sure if your meter can do this. 

Yes you can put grids on a switch, both of them have a coil, 2 little wires is what powers ( energizes) the coils signal comes from ecm, one is ground one is on the battery, you can tie two of the ground ones together and run it through a switch to ground. I'm using a push button one so I don't forget the switch in the on position. One of the best mods I did. It will set a code but will not show anything on the dash. 

Your grids coils could be failing and sticking on causing alternator to work overtime. 

[dieseldon]

1 hour ago, Dieselfuture said:

Set it to vac, it needs to be 0.03 or less 0.05 is on the edge. Test it on the alternator stud red lead and body of alternator black lead. Pcm control alternator not ecm, sounds like you may have did some damage to ecm because of high ac voltage coming from alternator. Ac volts should be minimal, diodes make ac go to dc, cuts the wave in half basically. Not sure if your meter can do this. 

Yes you can put grids on a switch, both of them have a coil, 2 little wires is what powers ( energizes) the coils signal comes from ecm, one is ground one is on the battery, you can tie two of the ground ones together and run it through a switch to ground. I'm using a push button one so I don't forget the switch in the on position. One of the best mods I did. It will set a code but will not show anything on the dash. 

Your grids coils could be failing and sticking on causing alternator to work overtime. 

 

So, a little confusing reading some old posts, some say any cheap dvm can do the job, others suggest you need a high dollar fluke or equal?? Am I missing something?

Volts ac, not millivolts?

I also have this old cat meter my Dad gave to me years ago, old cummins mechanic, wish he was still around.

 

 

 

Also do you disconnect power to the battery, the breaker most of us have before testing?

 

Not sure but it does seem like he was having some screwed up volt readings before this happened?? Maybe those grids were messing with alternator, just wish we knew what messed with what, in what order!?

 

Did you just power those grids with a random 12v ignition on power wire, or constant power from fuse box, a fused wire?

 

 Thanks again!

[Dieselfuture]

Volts ac, my meter auto adjusts the scale to volts or I can chose it myself. On your cat one try acv 2 that should set the max at 2 volts ac so if your alternator let's say putting out 0.05 it should display that. If you set it at 20 then it may look like 0.50 I'm not an electric guru just know what to look for. You don't need to disconnect anything when testing just make sure you're testing at alternator not at battery and turn everything off also disconnect your positive cables to grid heaters or drive the truck so grids quit cycling, I believe you need to go faster than 15 mph. Then make sure you leave the truck running before you test, if you shut it off and start it again grids will be going on off. That's why I say disconnect them. 

If you put them on a switch, just use any push button switch like a start button, so when you let go it shuts off the grids. The grid silinoids are at the bottom of driver side battery, 2 of them. Large wires are power from battery that go through grid silinoids to grids on intake, smaller wires that push on are what energizes them, one wire is positive and the other is what comes from ecm, gives it ground, that's the wires I ran inside the cab through a switch and to ground on the dash frame. So when you push button you give ground to the silinoids just like ecm would only now you're in control. I kinda suck at explaining this. But I love it now that I only use the grids when I need to and not every time I start the truck. Saves all kinds of wear and tear.

[JAG1]

It has happened to me twice now on the same truck about a year apart. The Alt got smokin' hot both times. Looked everywhere for a full sink to ground short and cannot find one anywhere. I think these rebuilt Alt's are doing that if they are overloaded and the overload is caused by something in the rebuild that has marginal workmanship or marginal parts. There is no way for me to know for certain of this, but seems to happen when I turned on both seat heaters after using the grid heaters. First time was a shorted cell in one battery and that was my fault. I think these ALT's are marginal in some respect. May not be what they are rated for.

[dieseldon]

 

 

3 minutes ago, JAG1 said:

It has happened to me twice now on the same truck about a year apart. The Alt got smokin' hot both times. Looked everywhere for a full sink to ground short and cannot find one anywhere. I think these rebuilt Alt's are doing that if they are overloaded and the overload is caused by something in the rebuild that has marginal workmanship or marginal parts. There is no way for me to know for certain of this, but seems to happen when I turned on both seat heaters after using the grid heaters. First time was a shorted cell in one battery and that was my fault. I think these ALT's are marginal in some respect. May not be what they are rated for.

Yeah, I can see someone's put a different alternator in, not sure what kind?

Did you have issues with the wts lamp and grid heater afterwards?

Again, not sure if grid heater got stuck on and messed with alternator or other way around? And then the real expensive part is the unknown ecm/pcm?!!

All these parts together would almost total that truck!

[JAG1]

1 hour ago, dieseldon said:

 

 

Yeah, I can see someone's put a different alternator in, not sure what kind?

Did you have issues with the wts lamp and grid heater afterwards?

Again, not sure if grid heater got stuck on and messed with alternator or other way around? And then the real expensive part is the unknown ecm/pcm?!!

All these parts together would almost total that truck!

I think the Alt's are so marginal in these trucks, relatively cheaply built inside with the real rating somewhere around half depending on age, temperature and condition. When they start getting warm their rating diminishes placing them on a road to deterioration with more overloading. developing heat, a purely destructive cycle. I cannot find any reasons for my two experiences with smokin hot ALT's. Nothing  to cause this full sink. I did see the B+ charge wire in line fuse bolt holding the lug terminal glowing like a light bulb is why WT told me it was a full sink to ground. After changing the ALT again, there has been no problem now for about 6 mos.

 

It would be wise to install better Alternators even tho many seem to do just fine for some reason.

 

To answer your question.... no, my WTS light was fine both times afterward. I did tear apart the grid heater relays and found nothing faulty except some small burn/ melt marks in the contacts. If it was the contacts failing to open, stuck together there were no significant tell tale signs with major burn marks.

Edited April 15, 2021 by JAG1

[dieseldon]

Still curious, does anyone know what the ECM controls besides grid heaters and electric lift pump?

If he's got a mechanical lift pump and manual heater switch, does he even need it? Does it have anything to do with the VP for instance?

    Thanks

 

[Dieselfuture]

It has fuel/timing maps controls idle speed etc, truck won't run without it. I guess it can if you hotwire VP, but then you're only stuck with idle speed.

[dieseldon]

2 hours ago, Dieselfuture said:

It has fuel/timing maps controls idle speed etc, truck won't run without it. I guess it can if you hotwire VP, but then you're only stuck with idle speed.

Thanks for the info, so that means whatever happened there was some life left in the ecm, or the truck might still be up in no man's land.

 

Anyone know if these trucks can be connected to expensive equipment and diagnose complete health of electric system or is it just a guessing game?

 

   Thanks again for any input!

[Dieselfuture]

Drb3 is my best guess, I'm sure there's other ways too.

[dieseldon]

So, we got .06 on alternator test which I guess is past marginal?

The thing is though that alternator is still getting hot for no apparent reason!

Heater grids disconnected, it's not smoking hot but still reaching 160* F in 5 minutes, crazy!

 Any ideas what they sam heck could cause that? PCM? A short somewhere?

 

He had it tested at parts store and said it was perfectly fine as far as charging, and bearings seem to be fine.

 

 

 He's tempted to put a different alternator in, but ?? I'd throw mine in there but at the moment we're in different towns.

 I'm assuming parts store might frown on testing one of theirs to see if it gets hot, LOL!

[JAG1]

2 hours ago, dieseldon said:

So, we got .06 on alternator test which I guess is past marginal?

The thing is though that alternator is still getting hot for no apparent reason!

Heater grids disconnected, it's not smoking hot but still reaching 160* F in 5 minutes, crazy!

 Any ideas what they sam heck could cause that? PCM? A short somewhere?

 

He had it tested at parts store and said it was perfectly fine as far as charging, and bearings seem to be fine.

 

 

 He's tempted to put a different alternator in, but ?? I'd throw mine in there but at the moment we're in different towns.

 I'm assuming parts store might frown on testing one of theirs to see if it gets hot, LOL!

If I'm not mistaken .06 is a fail. Needs to be less than .05. I think you said your batteries are new so no excessive load there from a shorted cell. 

 

A good test:  With the B+ charge wire disconnected from the passenger battery, place a rag under so it won't accidentally fall back on the positive post. If I remember correctly there should be no continuity between the alternator housing and the B+ terminal on the back of the ALT., if there is, alternator has an internal short. Just for the sake of saving the OHM meter you should disconnect both batteries as an OHM meter gets destroyed if any voltage goes thru it.

 

Only other issue would be something is causing a heavy amperage load on the Alt. and causing it to overheat.

[Dieselfuture]

Loose connection could also be a problem

[dieseldon]

Thanks for the help, probably won't mess with it again till he gets another day off next week.

[JAG1]

I think it's easy for our small alternators to be mildly overloaded and so with enough time will deteriorate to the point of an internal short. Just google forum talk about hot Alt's on our Dodge Cummins and you will see an inordinate amount of 'very hot' alternator discussions. It's uncanny how many and are numerous.

 

Dieselfuture cools his with beer.

Edited April 17, 2021 by JAG1

[Dieselfuture]

1 hour ago, JAG1 said:

Dieselfuture cools his with beer.

Yeah I like my beer worm , use my alternator as heat exchanger running beer through it