Bricknose electrical issues

[chillman88]

Hey all,

My 91 is having multiple issues possibly related.

1. The heater blower works fine and if you shut it off it stays running but when you restart it the blower won't work until you move a little bit.

2. My wipers wouldn't work this morning. I wiggled fuses under the dash and finally they started working. No clue what did it.

3. I had no turn signals, reverse lights or brake lights... until after I got moving and the heater kicked on. Then they started working? My hazards were working fine.

Any ideas where to start? Ran a 4ga cab ground directly to the battery last night. That was before these issues anyway but they've been intermittent all along.

 

[Thewespaul]

Yay intermittent electrical issues. Fun.

For the blower motor confirm you have 12v getting to it in the first place and that the squirrel cage is clear of debris, could be that you just have a worn out blower motor.

As far as wiggling the fuse box and getting stuff working again, check your fuses and if those are good then I would check the connections at the back of the block and make sure nothing is melted or loose.

 

[tradergem]

Just a wild guess, but have you checked the main wire harness plug on the passenger side inner wheel well for corrosion, or being melted down by the glow plug wires over heating?
My main wire harness plug recently cracked apart from the heat of the glow plug wires.

 

[OLDBULL8]

Wiggling those fuses probably made them make contact, those spring clips the fuses fit in can become corroded or bent so the fuse doesn't make good contact, make sure the fuse SNAPS in them. There is a HOT all the time from the pass side battery to the start relay on the fender, that connection feeds several wires, check it. Check the connector that lays over the pass side valve cover.

 

[chillman88]

Are the fuse boxes the same on gassers too? I might have a parts truck source...

As far as wiggling the fuse box and getting stuff working again, check your fuses and if those are good then I would check the connections at the back of the block and make sure nothing is melted or loose.

The fuse box had at one time melted where the blower WAS. It is now on it's own seperate loose fuse holder. All but the blower motor are new issues.

Just a wild guess, but have you checked the main wire harness plug on the passenger side inner wheel well for corrosion, or being melted down by the glow plug wires over heating?
My main wire harness plug recently cracked apart from the heat of the glow plug wires.

My glow plug wires don't go through that anymore, and the plug was NOT melted when I removed them. Do the power leads for the interior go through that?

Wiggling those fuses probably made them make contact, those spring clips the fuses fit in can become corroded or bent so the fuse doesn't make good contact, make sure the fuse SNAPS in them.

Wiggling the fuses didn't actually seem to make any difference. It wasn't until I started moving that the stuff started to work.

 

[typ4]

Dont rule out the ign switch, it has 2 battery feeds and several outputs, try wiggling the key a bit and it may pick up the contact, if so it may be the culprit.

 

[Thewespaul]

Are the fuse boxes the same on gassers too? I might have a parts truck source...



The fuse box had at one time melted where the blower WAS. It is now on it's own seperate loose fuse holder. All but the blower motor are new issues.



My glow plug wires don't go through that anymore, and the plug was NOT melted when I removed them. Do the power leads for the interior go through that?



Wiggling the fuses didn't actually seem to make any difference. It wasn't until I started moving that the stuff started to work.

Not sure if they are interchangeable for the bricknose trucks, I don’t have a gasser here to compare the two. I do have a bricknose diesel fuse block I can send your way, but since the issue was remedied once you got going I almost suspect the issue is in the engine bay, like a cold connector couldn’t make contact but once it got some heat it was able to make contact.

 

[chillman88]

Dont rule out the ign switch, it has 2 battery feeds and several outputs, try wiggling the key a bit and it may pick up the contact, if so it may be the culprit.

I don't know. The blower goes fine until after the motor starts. It seems like the vibrations from cranking cause something to lose connection. That's why I added another cab ground, I was wondering if it was losing ground.

Not sure if they are interchangeable for the bricknose trucks, I don’t have a gasser here to compare the two. I do have a bricknose diesel fuse block I can send your way, but since the issue was remedied once you got going I almost suspect the issue is in the engine bay, like a cold connector couldn’t make contact but once it got some heat it was able to make contact.

Well I have a fuse that has fallen out a couple times so I know I will need to replace it anyway. I know someone with a gasser they're scrapping and he's going to let me swipe some parts before it gets crushed. (Driving these with a leaking vacuum booster is really fun fyi)

I don't think it would be a "heat" issue. Truck was plugged in all night and had been running for 5-10 minutes. Nothing short of actually moving the vehicle fixes it. Oddly, revving and quickly letting the clutch out doesn't do it either.

I have new poly cab mounts which had no effect at all on this, so it's really odd that "moving" makes the blower work. 5-10 feet is all it takes.

 

[chillman88]

As far as power goes, I have changed a couple things.

I put a 3g alternator in. I used a mega fuse or whatever they are called rated for 175amps.

Power goes from the battery to the fuse box. From that same stud it goes to the fender solenoid. The other side of the fuse goes to the alternator. Power from the battery does NOT go through the fuse to the fender solenoid. 4ga wire in all mentioned circuits.

My glow plugs are run in a similar fashion from the battery through a 200amp fuse. 4ga wire to the relay.

Everything else is stock as far as I know except the power feed to the blower. It was cut off the back of the fuse block before I got it because it melted the fuse block. I put a fuse inline to get it to work. (The idiots had it hardwired to a fuel pump with no fuse and the blower disconnected).

 

[franklin2]

I vote the ignition switch also. I didn't think the later trucks had as much problem with this, but when it's cold this is a very common problem with the 86-dwn trucks. I kept driving mine, all I had to do was give the key a slight wiggle after the truck started. I could hear and see various things start working after that. It's aggravated by cold weather when the linkage in the column gets stiff. It got to be a habit and I found myself wiggle the key a little bit in everything I drove.

 

[chillman88]

Dont rule out the ign switch,

I vote the ignition switch also.

Well I guess if two reputable people both suggest the same thing... I'll try that tomorrow morning if I get my other problem sorted out. (Brakes stuck)

I didn't think the later trucks had as much problem with this, but when it's cold this is a very common problem with the 86-dwn trucks.

The 80-86 columns are mechanically the same as the 87-91, only the plastic trim is different as far as I can tell. I actually have a column from an 84 in my 91 now because the original column was horrendously loose!