Introduction + heater issue

[Not Alex]

Good morning all!

Despite my username, my name is Alex. I bought an M1008 sight unseen about 5 months ago while I was in Korea and just returned to get started wrenching on it. It received some 255/85r16 Falken Wildpeak MTs and a tan softopper to keep my stuff dry. It shifts through the gears just fine, actually reaches 60 somehow, and rides better than I expected these things to.
I'm happy with it!

Of course, as with most of these trucks, there's a couple of little issues such as rubber things rotting and electrical things not working right. I've got new window channel rubber and window seals arriving in a couple of days and I'm about to order new door seals. Luckily the wing window rubber is in half decent shape.

Now, the reason I decided to go ahead and make my first post is the heater. It worked fine when my brother picked up the truck and hauled it home, but now when I switch the blower on, the gen 1 light comes on. I thought it would be simple to troubleshoot through the TMs but I haven't gotten the hang of those yet and don't quite know how to navigate it.

Any help with the heater issue or TM tips would be appreciated. I'll include a couple pics of the truck as a benchmark.

Thank you!
-(Not) Alex

 

[Barrman]

When you turn the fan on any speed you get a bright red ALT 1 light and no air from the floor or the defroster, correct? I would suggest you remove the blower motor from the passenger side front fender/firewall area. A 1/4” drive socket set works best for me doing that. The screw at the outside bottom always wants to jump down between the fender and inner fender. Keep an eye on that one. It is kind of crazy.

If you get air moving and just a glow from the ALT 1 light with the fan on, that is not exactly perfect but pretty close to normal. Cleaning your blower fan ground alone might solve it.

 

[cucvrus]

I had this issue on several plow trucks, and I had an electrical shop put a separate relay in for the blower motor. I never done it to my own trucks but customers with snowplow trucks found that low glowing light annoying and that solved the issue. Running 24 hours straight with everything electrical system working to the max is going to show a weak point. That is the only one I found over the years.

 

[nyoffroad]

Check the alternator output, they have three 'legs' and if one diode burns out you lose 33% of charging and that would cause the light to come on when a load is put on it.

 

[Not Alex]

When you turn the fan on any speed you get a bright red ALT 1 light and no air from the floor or the defroster, correct? I would suggest you remove the blower motor from the passenger side front fender/firewall area. A 1/4” drive socket set works best for me doing that. The screw at the outside bottom always wants to jump down between the fender and inner fender. Keep an eye on that one. It is kind of crazy.

If you get air moving and just a glow from the ALT 1 light with the fan on, that is not exactly perfect but pretty close to normal. Cleaning your blower fan ground alone might solve it.

Correct. I definitely left out the important part of the fan not working, along with the gen 1 light coming on. I pulled the motor out and confirmed it does not turn on but it rotates freely though, so it's not a seized motor. I found that the capacitor had a bad break on one end of it though, so I went ahead and helped it come apart. Is the capacitor something I can just get rid of and connect the wire where it was? My understanding is that it's was just for reducing interference with military radios.

 

[cucvrus]

You don't need that capacitor. The wire will plug directly into the fan motor.

 

[Jeepadict]

You don't need that capacitor. The wire will plug directly into the fan motor.

Rick, I've seen them on civvy Squares a plenty...what is that gizmo there for since the wire reaches fine without it?

Sent from my SM-G970U using Tapatalk

 

[Mullaney]

Rick, I've seen them on civvy Squares a plenty...what is that gizmo there for since the wire reaches fine without it?

Sent from my SM-G970U using Tapatalk

.
It is to "quieten" the fan motor when running - with a radio running.
The fan will still squawk and squeal if the bearings are bad.

It helps isolate the motor from the rest of the electrical system...

.

 

[cucvrus]

This is what a new resistor looks like.

 

[WWRD99]

Correct. I definitely left out the important part of the fan not working, along with the gen 1 light coming on. I pulled the motor out and confirmed it does not turn on but it rotates freely though, so it's not a seized motor. I found that the capacitor had a bad break on one end of it though, so I went ahead and helped it come apart. Is the capacitor something I can just get rid of and connect the wire where it was? My understanding is that it's was just for reducing interference with military radios.

There needs to be a solid ground on the motor. You can run a separate wire to ground or clean off the mounting points of paint and such. I do a wire up to the bus bar right above it off a mounting bolt for the motor. It needs a decent sized wire since it can pull 20 amps on high which will turn on the gen light if the ground isn't good enough. Also check on the passenger rear intake for a braided ground or other wire type ground going to the cab...it is the only thing grounding the cab so it is needed. There should also be a battery sized ground on the same bolt coming from the lower bus bar. Spray some good lube in the bearing of the fan while you have it out too...look for a left over mouse house in the heater box as well.

 

[Not Alex]

There needs to be a solid ground on the motor. You can run a separate wire to ground or clean off the mounting points of paint and such. I do a wire up to the bus bar right above it off a mounting bolt for the motor. It needs a decent sized wire since it can pull 20 amps on high which will turn on the gen light if the ground isn't good enough. Also check on the passenger rear intake for a braided ground or other wire type ground going to the cab...it is the only thing grounding the cab so it is needed. There should also be a battery sized ground on the same bolt coming from the lower bus bar. Spray some good lube in the bearing of the fan while you have it out too...look for a left over mouse house in the heater box as well.

That's a good point. I'll check the cab ground and the contact between the motor and firewall. I confirmed continuity between the switch and the power wire connector, so it's gotta be a ground or a faulty motor. Now that I think of it, the motor did say "Made in China" so there's a good chance it pooped out. I'll report back in the morning. Thank you!

 

[adf5565]

Most likely the issue won’t be this simple, but my Gen 1 light started coming on when turning on the blower on my m1008. I don’t remember if the blower stopped working or not. It ended up being that the fuse spades were getting a little corroded, I swapped a new fuse and everything worked the way it should.

So it might be worth checking the fuse, maybe you’ll get off with an easy fix.