Main engine control wiring harness

[Rich Stern]

Long time no see, folks. Hope the Sport Trac faithful are all doing well.



My OD light started blinking. I checked my transmission fluid and under the truck to make sure I wasn't leaking anything. All looked ok. While I was under there, I noticed the wiring harness the leads to the tranny was frayed. I must have hit something, because at least a few of the wires are shot. It's in a tough to reach place for spliciing the wires while the harness is on the truck, so I'm trying to figure out if I can get the harness out without major surgery to the engine bay, or, if necessary, replace the harness. It looks like the harness is part of the main engine control harness.



Anybody ever serviced this part on their own?

 

[Mike Caldwell]

All the wires connected to the tranny are combined into one harness including the oxygen sensor between the cats. Your best bet it to try and undo all 5 or 6 connections and get some slack that way. IIRC the wiring harness is actually quite long once it is all undone. That would be my plan of attack for it, it may still be awkward to work on but at least there will be mobility in the harness.



Hope that helps

Mike

 

[Kevin Palmer]

Or, go to a salvage yard and cut it LONGER than what you need, then you will not need as much slack to work in the tight area...



Nice to hear from ya Rich.

 

[Todd Z]

Hey good to see ya around !!!!



I would get a pigtail.... if you can or splice in wires and use solder and heat shrink then rubber tape......



Done deal...



Todd Z

 

[LaRue Medlin]

HEY HEY RICH!!!

 

[Rich Stern]

Good to see all you guys. Good to be around. Thanks.



I managed to get the damaged section of harness disconncted from all the various plugs and attachment points, and pulled up into the engine bay. It was a knucklebuster. I now have enough room to do the repair. Whatever hit it took out a bunch of wires. I will probably use some weather proof butt connectors to do the repair, so I'll have that much more slack when making the connections. Then I'll have to work out a way to feed it back into position without stressing the connectors.



I guess I know what I'm doing tomorrow...

 

[Todd Z]

The weather ones are good, BUT i don't like them in a stress condtion...... Solder and shrink is the only way to fly with this man...



Todd Z

 

[Rich Stern]

Todd, you're probably right. If I was doing it on my workbench, I'd be all over it. Just not relishing doing a bunch of soldering learning over my fender. But if I must, I will.

 

[Wes Davis]

Put a sheet of heavy cardboard over your engine and use it as kind of a work table. Punch a hole or slit in the cardboard to pull your wiring harness through and it should help to hold the harness in place for you while you work on it.

 

[Todd Z]

I remember when the main harness of Rachel's BII got burnt on the exhaust manifold.... I think it was something like 40 wires to cut and splaice..... Took a good 8 hours..... Sucked...



I know your pain..



Todd Z

 

[Kevin Palmer]

Rich,



IF not the solder and heat shrink method, then after you are done I suggest using liquid tape at least as it will handle heat as well as seal the wire very well in the area you do the work...



[Broken External Image]:

 

[Rich Stern]

I started with solder, but eventually changed to weather proof/heat shrink butt connectors. Try as I might, the soldering was too difficult because of the space and cable length limitations. I bought the best connectors I could find, and got a high quality crimper that did a good job. The connections are very solid, and the heat strink ends worked well. I then strain releived everything with ty-wraps, electrial tape, and a cable conduit. Was plenty strong. Got everything back in position and plugged back up.



Unfortunately, my O/D light is still winking at me, and my check engine light is on. Truck can go forward or reverse at slow speed, but balks at shifting and very runs rough when encountering any resistance (like the hill on my driveway).



Todd, question: A handful of wires that I had to splice had duplicate color coding. (white/black stripe, blue/orange stripe). I tried to piece them back together to the correct ends, based on comparing the separation damage. Do you know if multiple wires color coded the same way carry the same signal, and are just bound for different connection points, and perhaps it doesn't matter which is spliced to which?



Also, I assume that having the battery disconnected while I was doing this is enough to reset the computer? Any other needed procedure?

 

[Todd Z]

Rich,



Yes the reset was the best......



The wires i believe do carry different tasks.....



Steve M has the manuals and i et can get you the schematic you need to confirm or deny the wiring..



Todd Z