1994 Peterbilt 378 Cab Fire - Wiring Harness Fault

[cfherrman]

I have a 90's 377 cab that should be the same except of the l10 engine part. Of course I'm in Kansas but let me know what I can do to help

 

[mekanik]

Have you looked into maybe your insurance will pay for the repair?
I replaced the cab harness on a 95 Kenworth for an electrical fire. It was a plow
truck so there were quite a few extra switches and such. It was around 40 hours
work plus the harness. Also see if a Peterbilt dealer will contact the factory and
see if they will build you a new harness.

 

[631G]

Have you looked into maybe your insurance will pay for the repair?
I replaced the cab harness on a 95 Kenworth for an electrical fire. It was a plow
truck so there were quite a few extra switches and such. It was around 40 hours
work plus the harness. Also see if a Peterbilt dealer will contact the factory and
see if they will build you a new harness.

I have a call into the insurance company and got sent to a different dept. because they want to know what caused the fire. My guess is they're getting ready to argue on why they don't have to pay.

I called the dealer this morning to get a part number and they were helpful. But the harness that matches this truck is going to be near $6,000. I had not thought about asking for a new one to be made. Might be worth a shot. This truck shipped with a 3406C and we have a B in it now. Might be an opportunity to get a harness made that suits the B series instead of the C series for the truck so we can have all the gauges and the jake break again.

 

[631G]

Two speed rears? Were they pulling superloads?

Not sure. Best I can tell is that this truck came from some one pulling hills and/or heavy loads all the time. The paint job on it reminded me of my power plant days when we hired out Bigge for heavy haul to bring in the harps and other heavy components on the steam side of the plant. Maybe it was once one of theirs.

 

[631G]

Fire started at the fuse/distribution box. It's not uncommon to remove a bad relay
for lighting and find the plastic is melted around the four spade connection and on
the other end find the connection at the toggle switch has been hot too. Especially
1987 through 98. A true Pete issue given age, dirt and moisture.

Well for background the A/C randomly quit about 1 week before this happened. Had been working fine and then nothing. Maybe we had a fault and that then grew into this disaster.

 

[631G]

Nothing in that wiring setup gives me any confidence that the same thing wouldn't happen again. The whole deal looks like spaghetti strung through trees.
The chances of short circuits with poorly laid out and poorly-secured harnesses is huge. We lose a heap of trucks every year around here with major fires caused by short circuits, and they're usually a total
loss.

And the worst offenders are the units with a high level of electronics, and a high level of emission control equipment.
So much so, guys are buying old trucks from the 1990's and rebuilding them from the ground up, they are generally so much more reliable.

But I'd be going through the harness on any replacement cab you buy and ensuring the wiring is properly secured at regular intervals, and that pinch points are avoided or the wiring is properly protected at those points.

I like your description. We thought that was what we were getting here; simple reliable old truck. Everything was working well on the truck electrically, so we never really considered there was a potential fault waiting to happen. As I continue the search for a cab this will play a big role in evaluation of the purchase.

 

[631G]

Would anyone know what year and potentially other series Peterbilt day cabs will work with my truck? I have no idea what's actually usable for swap over.

 

[Truck Shop]

I like your description. We thought that was what we were getting here; simple reliable old truck. Everything was working well on the truck electrically, so we never really considered there was a potential fault waiting to happen. As I continue the search for a cab this will play a big role in evaluation of the purchase.

Here is the interesting fact about Peterbilt.
The last 359's were built in early 87, 1987 was first year for the later semi flat dash.
The 359 prior had the corvette dash with the circuit breakers mounted in the left
side of dash. The corvette dash had very little issues with harness and breakers.
When Pete moved the fuse panel to the floor is when electrical issues began to appear.
Pete also had a high amp breaker panel in the left kick panel, those were known to rot.
Mud, water, chemicals tracked in caused a lot of problems with the later cab.

 

[Truck Shop]

Would anyone know what year and potentially other series Peterbilt day cabs will work with my truck? I have no idea what's actually usable for swap over.

Assuming it has a flat dash, any of the 379's will work short or long hood. The 377 will also work.
As long as of the same time period.

 

[cfherrman]

I was told the 377 just has high cab mounts over the 379 and a different hood obviously.

 

[terex herder]

You can try this place. He buys a lot of 3406 trucks, as he has a customer for all the engines he can get.

Robert Ullom Used Truck Parts - Largest Supplier Of Used Truck And Trailer Parts In Kansas and Nebraska

Largest Supplier Of Used Truck And Trailer Parts In Kansas and Nebraska

www.robertullomusedtruckpart.com

 

[631G]

Pulled off the fuse panel to see what it looked like and here is the damage. Looks like there may have been a hard short from the main cable putting power to the panel as all of the fuses were blown. May have just a likely been the cable insulation melting off and them making contact with the others near by but this was an idea floated to me.

So far I've managed to find a good cab in Idaho and 1 here in Atlanta that match up really close to our truck. They're both very reasonably priced. the search continues....

 

[631G]

Just finished a call with Peterbilt of Atlanta and he was able to do some digging. Apparently, the serial number of this engine we have in the truck now is not a 3406B it is a 3406C. He said that some folks would take the pump off and remove the electronic governor and replace with a manual governor. The truck I am looking at in Idaho also shipped with a 3406 C and looks nearly identical to my truck from the photos of the engine harness setup and plugs. Might be onto something here...

Here are photos of my pump. I think this pump retrofitted back to manual governor? It looks that way to me given there is a rod going back to the pedal.

 

[Truck Shop]

Yup. Looks like a driveline socket on the floor. It was real common to convert a 4CK to a
manual pump and advance. Who has the cab in Idaho? Holst?

 

[631G]

Yup. Looks like a driveline socket on the floor. It was real common to convert a 4CK to a
manual pump and advance. Who has the cab in Idaho? Holst?

Just so I'm on the same page with you, you agree that I've got a manual governor, or I need to go look for the hole in the floorboard you describe?

Yes Holst is who has the cab and its in great shape.

 

[Truck Shop]

Yes that's a manual injection pump. About a 95% chance it was Holst.

 

[mekanik]

Holst? PEEC?

 

[92U 3406]

Personally I wouldn't waste my time putting a 30 year old wiring harness into the truck. Just asking for endless electrical problems. I'd either go new or junk the truck.

 

[Truck Shop]

Holst? PEEC?

There's only one main salvage yard in Idaho that advertises nationally-Holst.

 

[Truck Shop]

Personally I wouldn't waste my time putting a 30 year old wiring harness into the truck. Just asking for endless electrical problems. I'd either go new or junk the truck.

He's looking at replacing the entire cab, dismantlers won't part out a cab or sell in many cases
the harness from one only on rare occasions. Pete won't custom build a harness back that many
years. I don't know any manufactures that do. About the only thing they continue to supply
is a distribution box/fuse panel.

It's one of the issues that can happen running older equipment to stay away from emissions.