M1010 electrical issues

[nedbread]

Hello!

I have an M1010 with 32k miles that runs and is in good condition.

The starter went bad and I had to manually remove the battery cable from the 24V + terminal to get it to stop turning. Big flash and spark and the battery post melted a chunk off of it.

I replaced the starter and whirrr up it started.

Only problem was that immediately after this repair a fuse started blowing moments after the truck started up, my dash lights would go out and I would not be able to start it again without replacing that fuse.

Annoying.... I checked the installation of the starter and the wires around it and it all looked fine.

Recently -- after a handful of successful starts -- I tried to start it and it would not turn over. I tested the batteries at 12.36 (the first battery, goes to 0V during cranking) and 11.8V (top battery, does not change during cranking). Cleaning the battery terminal post did nothing. I was able to jump start the truck and it ran fine. However after driving it 50 miles the batteries had not charged up at all.

First of all I would like to diagnose why this fuse is blowing. I suspect it could be related to a bad idle up solenoid, a mechanic told me mine was bad. It had never worked since I bought the truck. Then after the starter went, all of a sudden the idle up solenoid works again. The fuse seems to blow when the idle up solenoid finishes its cycle and the idle returns to normal. **What should I do to diagnose this fuse?**

Second, **Does anyone think they know what is going on with the no-start?** Does that top battery need to be replaced?

Thanks!

Ned

 

[MarcusOReallyus]

Sounds like you fried your batteries and possibly one or both alternators, and you likely popped a few fusible links, too .

Autozone will test your batteries for free, so that's a good place to start.

Then tackle the fusible links. See the "Helpful Threads" sticky at the top of the forum. Lots of good info on just about everything, including starter run on and fusible links.

Once you get all that squared away, see the "doghead mod". BUT, you really don't need that massive relay. A good quality 30 amp automotive relay will work just fine there. The concept is important, thought.


Lastly, tackle your alternators. Top of the forum, thread on testing alts while on the vehicle.

And make sure you check ALL of the above. If you miss something, you can wind up in a vicious circle of frying this component, then that one, and on and on. You need to get them ALL fixed.

 

[nedbread]

Good afternoon.

I have been tinkering with this problem for a while. It did seem as though I had a short somewhere in my electrical system, because of the fuse blowing. I began by looking through the wiring diagrams and identifying which electrical systems were on this circuit. Then I tested each of the systems in turn. The first thing I did was repair the fast idle solenoid. That did not fix the issue. The second thing I did was repair the voltmeter (on the dashboard). That also did not fix the issue. Later on I was able to identify a diode in the voltage regulator that was bad (shorted out in both directions). I went to napa auto parts but they do not, I found out, carry a supply of single diodes for general purposes. They of course sell a voltage regulator for $300 but it is different than the one that is installed on my vehicle. The Napa employee says this is because the military installed a different voltage regulator on the M1010, which I do not doubt.


I shall order a replacement diode, however, in case the voltage regulator needs to be replaced, should I try to replace it with the one that is currently installed, or go back to the stock part that was in the Suburban, Blazer, etc.?

Thanks,
Ned