Engine overheat help

be aware that the liting circuits are not hot to chassis ground

 

Are you saying there is a separate return wire for what is normally hooked to chassis ground?

 

The lighting on this vehicle is controlled by the body control module. That can shut circuits down if it detects a fault. Codes might need to be reset in the bcm after the fault is fixed. I have access to wire diagrams if it will help Well Seasoned? Feel free to pm if you like. Around the time this vehicle was designed people decided it was better to make things more complicated than they need to be…

 

2 common issues for this year are the ground by the drivers rear tire rotting off and poor pin fitment at the bulked(firewall) connector. By the parking brake control.

this is why I suggested checking the ground circuit first.

 

The “big wire” that rots off on the drivers front fender does not apply to this model year.

 

not only that but some of the circuits are bidirectional ( mostly engine controls) if this is a gasser the the control modul for the fuel pump ( low pressure) is located above and ahead of the spare tire. these corrode out from the bottom.

 

Sorry to hear that,

 

Ain’t that a b*itch! I’m on the road for work today. The pcm is on the passenger side cowl area. There are three big connectors going to it.

the truck will crank but not start?

 

I believe you are referring to network circuits. Every module will have at least one dedicated power and ground. The tricky part comes when a network circuit isn’t intact. Open or short. It will take the network down and the vehicle will be a brick.

 

Looks like this CAN bus crap started on the gasser F250's in '05...looks like I dodged another bullet with my 2003.
Don't need anymore headache than I already have with the 08 Honda Odyssey...darn thing gets a little moisture in the wrong spot and about all it will do is start and drive, almost nothing works otherwise...low beam HL only, high speed wipers only, no turn signals, manual heat only...the last round with it I never found anything wet and the trouble spots were already packed in dielectric grease (per Honda) finally chased around heating everything with a hair dryer and suddenly everything is fine...covered all the trouble spots with plastic until I can find/fix the leak...which turns out to be the roof body seams from what I'm reading.
There's kinda something to be said for 90's vehicle technology...

 

Multiplex electrical is just an awesome failure in the north.

 

Well Seasoned ,I don't know if this is similar or not; thought I'd post my own experience with ford and elec problems.

About 40 years ago, I started having issues with my ford pickup. Could never really trace it down and I didn't rely on the truck for anything but going back and forth to work. Sometimes it would start, sometimes maybe not; lights blinking on and off; I think there may have been some really bizarre occurances like pressing on the horn butrton and the wipers would come on....that sort of stuff.

Insurance came due for the next policy term and in order to save $$, I decided to cancel full coverage on it. (big mistake)

A few months later, one day the dog was barking (alert worrried serious something is wrong type of barking)...sure enough, the truck was on fire in the yard.

Total loss.

It ended up being the multi-plug electrical connector between the interior cab and the firewall...where all the wires pass into and out of the cab.

 

What year truck?

 

Had a 2013 f150 with similar issues, ended up being the run/stop relay under the hood fuse box, not sure off the top of my head if yours has, should have something similar

Also have had weird things happen when one completely unrelated module goes haywire and causes issues in the network

Unfortunately the oems feel even the simplest task needs 3 modules involved, sometimes a system reboot works by removing battery cables and rubbing them together to discharge all capacitors in the network