M1008 alternator issues, and other stuff

[MadWooter]

Hello everyone!

I've watched this site for some time, particularly recently as I've purchased a 1986 M1008 (and have just finally been able to get it tagged) and have been doing repairs on it.

Now I seem to have an alternator problem, and I'm left scratching my head and hoping that someone on here will be able to point me in the right direction. I've read a whole lot of threads on here about different alternator problems, but no one seems to have had exactly the same problem I've had, and a few links I've found seem to be dead. So, here goes.

When I got the truck, both batteries were completely dead because it had probably been sitting for a couple of years (there were even some sort of coccoons in the treads on the tires). Anyway, after I got new batteries and started driving it in the last week, I noticed that the belt on the driver's side alternator was loose (and making a whole lot of noise), and eventually tracked it down to two missing bolts on the power steering mounting which were letting it flap around. I've replaced the bolts, but now I seem to have a new problem. The other day I thought that the Gen 1 light was on, but it was very faint and almost invisible in the daylight. The voltmeter was pointing right between the yellow and green areas. However, at some point the light went out, the voltmeter went back into the green, and I was able to drive the truck offroad for several hours. Last night, however, this happened again, but the light did not go out and now it comes on whenever I start the truck. It glows very faintly (much less than the Gen 2 light) before cranking the engine. Using a voltmeter, I see that the front battery has less voltage than the rear, and that the driver's side alternator does not seem to produce power.

Looking at other threads on here, I've already tried cleaning corrosion from around the Gen 1 lightbulb, but there was none. The alternator is spinning freely and not making noise, but produces no power. Given the writing on the alternator, it seems to have been replaced in '03, but like I said I don't think the truck has moved for a few years. There does not appear to be any corrosion on any of the alternator terminals.

Is there anything else I should check (a relay for the charging circuit, maybe?) or is it safe to assume the alternator is fried somehow and needs to be rebuilt? I find it strange that it seemed to fail the other day but just came back to life on its own. Also this problem only seemed to start after I replaced the bolts holding the PS pump in place. I don't know too much about this truck, and my only other real experience with working on a vehicle is my '88 Celebrity. Any help would be greatly appreciated on this.

Oh yeah, and does anyone have any idea why turning on my windshield wipers in any way also turns on the wash mechanism? Bad switch maybe?

Thanks a bunch in advance, and sorry about this huge post.

 

[Westech]

"Oh yeah, and does anyone have any idea why turning on my windshield wipers in any way also turns on the wash mechanism? Bad switch maybe?"

Mine does that from time to time also. I really don't know why. The pump and wiper motor are all in that same unit. I would think there would be some crud or a stuck relay in there. I am thinking of taking it apart or just replacing the unit. As for the alt not charging, it could just be going/went bad.

 

[uscgmatt]

Check the plug on the alternator. Make sure you have 12 volts on the red wire and the plug is making good contact with the alternator. The brown wire goes to your light. Hope this helps.

Matt

 

[MadWooter]

I did try wiggling the plug around, but I didn't actually take it off or check voltages. If the red one has 12V, is that with respect to the chassis ground? I would suppose that the 12V there is connected to the front battery and therefore the chassis ground.

I'll also have to look into the wiper motor assembly. Thanks.

 

[Michael]

I would clean both ends of the ground wire on the alternator next. Then I would move to all the electrical connection in the charging system. Trucks that sit tend to get a lot of corrosion.

If it still doesn't work, I would just pull it and have it tested. Be sure to find someone who knows how to hook it up with the isolated ground.

 

[devilman96]

Why would anyone work on a electrical system of a vehicle with out having a TM in front of them?

Why are the rest of you not pointing him to it?

You could try going here... http://old.steelsoldiers.com/index.php?module=pagesetter&type=file&func=get&tid=1&fid=file&pid=10

and reading... "ALTERNATOR TESTING AND REPAIR (ALL EXCEPT M1010)."

 

[Westech]

Someone GRUMPY?

 

[MadWooter]

Thanks for the manual. I had previously found a operator's manual for it, and have been using a Haynes repair manual meant for the civilian trucks. Not everything matches up. Hopefully this will be some help. I hope it does come down to just a corroded contact somewhere, maybe at the voltage regulator. Any idea why it might have gone out the other day and then just come back? I'm about to just start banging on it and hoping that technique fixes alternators as well as it fixes everything else.

 

[Crash_AF]

Since it came and went, I'd almost guarantee that it's a corrosion/connection problem.

BTW, the light is supposed to come on when you turn the ignition to 'ON' and the engine is not running.

Later,
Joe

 

[MadWooter]

Yeah, I know it's supposed to come on with the key in the "ON" position, but its the dimness of it that gets me. The Gen 2 light is bright as can be before starting the truck, but the Gen 1 light has the same dullness it has while the truck is running. The alternator doesn't seem to be producing any power at all, so I'm not sure what to make of that. In other threads people have said something about the light being dim with alternator problems, but nobody seems to know why. You would think if the alternator is not charging it would be bright as can be. Probably some bad design.

 

[devilman96]

Someone GRUMPY?

Naw... Just tired of the bad ideas and bad advice in this fourm... yank this, jiggle that, cross this... Spin on one foot while smacking yer self in the sack with a hammer would make more sense... and prolly be more productive.

The next posting he puts up will be because BOTH Gen1 and Gen2 lights are now on... and some goober will start in with Roscommon 12V conversions *shudder*... then we have another 12V truck which will have starter, glow and cold weather starting issues to post about later down the road.

Electrical is daunting... Give help that goes set by step. IMHO... Unless you have the wiring diagram memorized you should have the TM out when working on electrical... and if your going to post advice make sure the person has the most basic tools avlaible... first one being the correct manual.

Madwooter... Toss the Haynes, the glow plug and charging system are totally diffrent... You also need to find the manuals that end in 24, 24P and 34P (i gave you 34)... 24 being unit level maintenance (basic repair) and the -p manuals both being parts... again 24p being more general and 34p being more complex.

Stop bouncing around and check the Alt's inputs and outputs so you know if its even the alternator or not and or get it into a shop for a spin test... Make sure you know AND they know its a isolated ground on the alternator when testing it.

 

[MadWooter]

Heheh, I have absolutely no intention of converting it to 12V. I had to stop working on it because it was getting dark and really cold, but my plan of action for tomorrow will revolve around checking voltages in different connections (as per the TM's troubleshooting) and taking that sucker to Autozone to have it checked. I will certainly make sure to tell them it has the isolated ground. I took an alternator to them once which was actually squealing, but still producing power, and the tech's advice was to put it back because it still worked. I don't have much faith in the automotive knowledge of parts salesmen.

 

[BobM]

In my thread that is titled "My 1008 is making me go bald", I discussed the same problem that you have. And like you my wiring had been "adjusted" by someone so the TM didn't do me much good. Sorry Devilman, but the TMs don't actually cover everything IMHO.
Anyways I HAD taken all the connections apart several (OK,OK a COUPLE) times and cleaned the connections. And when I would adjust the belts or do some other unrelated thing, that darn Gen 1 light would come on, go off or even sometimes work properly.
Finally I took the wire connectors out of the plastic clip on the alt and severely cleaned the brown (Mine had actually been changed to black I believe) wire and Presto, Chango, it started working right and has stayed working for a while now. Hopefully my talking/posting about it won't jinx me!

 

[MadWooter]

As an update, still no luck. I've found that whoever used to work on the truck had a habit of doping electrical connections with what appears to be axle grease, and it makes for a mess when trying to clean it. I fiddled around with the plug on the alternator, with the brown and red wires, but with its size and the fact that it was full of black grease I didn't manage to get much shiny metal. Didn't seem to fix the problem, though. The light has gotten even dimmer, but that might be due to the battery slowly wearing down.

Before I go chasing every possible electrical point, I'm going to get the alternator spin tested. I would have today except for the freezing rain, and now that I can work on it stores are closing.

I did, however, manage to fix the windshield wiper problem. I just clicked the little wheel inside of the wiper controller a few times and now it only pumps fluid when it should.

 

[devilman96]

Mad what are your voltage readings going into and out of the alternator?

 

[MadWooter]

Between the positive and negative terminals? The same as the battery (going from about 11.5V just after starting and rising back to around 12.5V). With the engine off and the glow plugs and starter not used for a while the red wire of the plug reads about 12.5V and compared to the ground the brown wire going to the light shows nothing. I only checked the plugs with everything off, no key in ignition or anything.

I don't suppose it's terribly important now, because I found an Autozone that was open, got them to test the offending alternator (after explaining to them how to hook up the isolated ground), and although it seemed to pass the diode test it failed shortly thereafter (on the rectifier test I think, but I'm not positive). So, tomorrow morning I get to call around to try to get a rebuild. BTW, does anyone know of any good shops that do rebuilds in northern DE?

I'm actually kind of glad that the alternator was the problem and not some crusted over wire in some impossible-to-get-to place. I wonder if the P/S pump being loose and letting the belt flap around had anything to do with killing the alternator.

 

[devilman96]

Well it sounds like you found the problem at least... If you cant find a shop to rebuild it locally (shouldnt be to hard but that pends the area you live in) let me know, I have these on the shelf ready to ship.

 

[jj]

There is a place in Reading,PA., not too far from "Northern DE" that does outstanding work. Called Automotive Electric, 610-376-4032. The gentleman's name is Fred E. Richardson. He knows his stuff, he has been in business at this location for better than thirty years. But take cash when you go, he doesn't buy into the whole credit card or "do you take checks?" stuff. Maybe that is why he is still in business.

 

[csramsey640]

Why would anyone work on a electrical system of a vehicle with out having a TM in front of them?

Why are the rest of you not pointing him to it?

You could try going here... http://old.steelsoldiers.com/index.php?module=pagesetter&type=file&func=get&tid=1&fid=file&pid=10

and reading... "ALTERNATOR TESTING AND REPAIR (ALL EXCEPT M1010)."

Not too many people keep a 500 amp test stand handy, sorry that troubleshooting is pretty hard to duplicate because it was written as though we all have access to MIL tools and testers.

 

[MadWooter]

Heh, yeah I wish I had a whole load of automotive testing equipment, and a big garage, and a machine shop, and, well, a whole lot of stuff. Anyway, I found a place just up the street from me to rebuild it, it's actually where I got the batteries I have in the truck now (some sort of generic remanufactured commercial truck batteries, but they work great for $35 a piece and they fit right into the holders). Unfortunately all but one tech took off this week, so I'm not sure when I'll get it back. Only about $100, much cheaper than a new one, and the guy I gave it too has worked on them before for some CUCV collector in my area. I'm fairly confident that I'll get it back with the ground wired correctly.