M1031 Electrical GURU's, Inside plz.

[FORD RECOVERY EXPERT]

I have a 1986 M1031 Contact Maint truck.

The truck is completely stock except DRW front Hubs/HMMWV Tires/wheels.

Now, The problem I'm Having is:

Sometimes all is well, and sometimes (Randomly) the following stop working;

The Battery indicator gauge.
The GENSET Throttle Governor Circuit
The "Wait" lamp
The Water in fuel lamp
The PTO indicator lamp
and maybe some other things I haven't noticed yet.

Also, The "Upper" Alternator IS producing 15.5 volts with the engine running, However, This voltage IS NOT reaching the "Upper" Battery...

and the "Gen 2" lamp is not working at all, even during lamp check...

I have an extensive knowledge of automotive electrical systems...
I am only posting this to see if someone has an idea of a common point between these items (Ground, Junc. Block, ETC) or has ran into this before...

Thank You in advance

 

[Warthog]

Welcome to SteelSoldiers

First and easiest check is the ground wire next to the parking brake. There is a "spider" 6-lug connector with the ground wire mounted to it. It is a known problem area.

Have you ever removed and cleaned instrument cluster?

We do have FREE technical manuals that have troubleshooting and wiring diagrams in them.

 

[Warthog]

What is the "upper" alternator and battery?

 

[Keith_J]

What is the "upper" alternator and battery?

The rear battery and right alternator are sometimes termed the upper.

 

[FORD RECOVERY EXPERT]

No on the instrument cluster, although I have read that if the bulb for GEN2 is expired, then the alt loses contact w/ the battery?


also, the strip you speak of near the P Brake, I haven't been to it yet as it is raining here, but that sounds like a good place to start...


the "Upper" term is coined due to this pair being responsible for the "Upper" half of the 24v

 

[Keith_J]

No on the instrument cluster, although I have read that if the bulb for GEN2 is expired, then the alt loses contact w/ the battery?


also, the strip you speak of near the P Brake, I haven't been to it yet as it is raining here, but that sounds like a good place to start...


the "Upper" term is coined due to this pair being responsible for the "Upper" half of the 24v

The indicator bulb is required to energize the regulator. Without continuity through the bulb, the regulator in the alternator cannot energize the field. Meaning no output. Alternators regulate the output voltage with the field current, this varies the magnetic field. A stronger magnet means higher voltage.

 

[FORD RECOVERY EXPERT]

Ok, then I will investigate further tomorrow on both the bulb, and the ground block

I will give a sit rep after

 

[Skinny]

Sounds like it is time to park it and tear in. Pull every electrical component apart and clean it, rebuild both alternators, replace both batteries, change out the box filter for a spin on, change all glow plugs and verify proper operation, do a resistor bypass mod, doghead mod, etc etc etc

Then you will be very happy with your rig!

Be sure to post up some photos of your new truck.

BTW, does anyone know how many M1031's were produced? Just out of curiosity...

 

[Warthog]

Just checking on the "upper" to see if you might have the M1010 setup.

Check this thread for the "spider" connector at the emergency brake.

http://www.steelsoldiers.com/cucv/50551-cucv-switches-diodes-relays.html

Sometimes it is mounted on the brake and sometimes next to it.

 

[FORD RECOVERY EXPERT]

ok, still raining hard here... Will post back my findings asap

 

[FORD RECOVERY EXPERT]

Spider is good and tight, GEN2 lamp is good.... Still have to clean inst cluster & re-install.

Going to work for my week, I'll see more about it next monday.

 

[FORD RECOVERY EXPERT]

Spider is good, Instrument panel cleaned, die electric greased and reassembled... tommorow will tell the results

 

[FORD RECOVERY EXPERT]

Ok, been putting this project off a while, but... The bulb is good, and so is the spider lug near the p-brake... Where to next?

 

[llong66]

The things you mention that you have in common w my M1008 are all on one fuse, number 17 I think it is, the engine control fuse. I found this out earlier this year and the problem ended up being the coolant temp switch at the rear of the pass. side head that controls the fast idle/advance on the injection pump. The switch must have been shorting out internally causing the fuse to blow. I am not sure what may be happening to cause the same symptoms and not blowing the fuse and you have some items on the circuit that I dont on a M1008. Maybe unplug the switch at the head and see if the problem goes away and if it does, then plug it back in and check each plug at the injection pump, might just be one of the solenoids that controls either the fast idle or the cold advance.
Good luck!

Greg

 

[Keith_J]

Fuse clips in the fuse box get dirty, weak and then can cause issues. Weak clips can be retensioned. The right alternator is switched on with a relay, this can also be dirty in connections (plug) or contacts (check blackout light operation, if that works, swap relays).