A couple electrical issues with M1009

[jward37]

Hi, I just bought an M1009 (my second one) and have been able to get all the electrical working for the safety inspection except for 2 things. One is the Gen1 light. I replaced both alternators as gen1 was outputting 17 volts across a new battery and gen2 just 12.5 volts, probably the battery voltage. Both gen1 and gen2 lights were off in this configuration. With 2 good alternators putting out ~14.5 volts across each battery the gen1 light stays on, yet a bit dim. What triggers these lamps to go off? Typically they are both on when I first start the vehicle, then a punch to the accelerator pops them off. These alternators came off my first m1008 which has become a bit rusty. The other thing that isn't working is the windshield wiper hi speed, which does nothing. Low works fine. Thanks.

 

[jward37]

I'm scanning the schematics right now.

 

[OL AG '89]

If the truck isn't dling fast enough the lights will stay on, at least that's as I understand the circuit.
read through the troubleshooting section and you'll find several things to check. Done in the correct order you will avoid buying additional uneeded parts.

 

[1stSarge]

Welcome!

It seems at first glace that the belt might be slipping. Any noise? Does it need replaced? There is a lot of drag on an alternator pulley that is putting out its full charge.

 

[sierrajcharlie]

If that doesn't do the trick try replacing the heater fuse. There seems to be a hidden circuit going through that with Gen1. At least that's how I fixed my Gen1 dim light issue. But mine only would be on dim when I had the heater going. I don't imagine that's an issue in Hawaii! My fast windshield wiper speed works when it darn well wants to. It has to be in the switch but I'll live with it instead of tearing things apart.

 

[jward37]

Thanks for the suggestions. I was hoping the 17 volts from the bad gen1 had tweaked a voltage divider or some comparator on that light since it was not on with the 17 volts. And I was hoping the wiper issue was something outside of the switch since I really don't want to have to pull the steering column stuff to replace it, which I think is the case.

Just a fun note. There was a lack of power driving this home after purchase. Solution; replaced fuel filter which would not bleed air and was full of brown rusty fuel. The brake fluid was mud, but the brakes work. Scraped out the mud, shot in new silicone brake fluid. Brakes still work, but seriously ready for bleeding after I soak the bleed fittings in penetrating oil. Changed oil first thing. Next transmission fluid and filter (fluid looks clear) and then transfer case and differentials. Radiator and coolant looks great, but I will replace the thermostat valve. Then on to the brake hardware inspection. Why did I buy this truck again?

 

[Warthog]

Have you visited JATONKA's website and downloaded all the tech manuals?

www.jatonkasm35s.com

We usually have the manuals on this site but the old server is offline so, JATONKA is hosting some of the more popular manuals on his site.

 

[jward37]

Yeah. I have all the manuals. I kinda know this truck. It's just been a few years since I worked on one. On my first one I reverse engineered the glow plug card and rebuilt it. You can also bypass the card and just put a push button on the dash. So I was hoping for something not to difficult with the wiper and gen1 light. I hope to sort it out this weekend and I'll post if successful. I found a lot on the alternator system out there and will be rebuilding 2 very soon. Looks like the cost will be around $60 max each in parts. Just a note; the part numbers in the manuals crossed over perfectly with Napa and Carquest, which surprised me.