melted engine wire harness (1 Viewer)

[stuckthrottle]

I did a search and found this thread: https://forum.ih8mud.com/showthread.php?t=144478

Which is great if I'm going to replace the entire harness. Yesterday I was puting along a few blocks away from my house when all of a sudden my LC sputtered and shut off. I had a friend drag me back home and we found a wire that powers the alarm/engine shut off that had come undone, we plugged her back in and everything was back to normal, or so I thought.
We let it run for a few minutes then shut it off, later that night I had to get dinner but I only made it a few blocks before the sputter came back only this time after it died and tried cranking it over again lots of white smoke came from under the hood.
We dragged it back home and started looking for the problem...and we found it (see attachment).

Has anyone ever had this happen to them? We figured the harness had been rubbing in the pcv valve metal hose (after the big nut) but dont know what else could have been the problem. Not one cable is damaged all the way through, they all are melted in the same spot.?

 

[lagwagon]

I haven't seen that happen but have heard of it. I have a harness if you need it. PM if you do.

 

[firetruck41]

Has anyone ever had this happen to them? We figured the harness had been rubbing in the pcv valve metal hose (after the big nut) but dont know what else could have been the problem. Not one cable is damaged all the way through, they all are melted in the same spot.?

Maybe heat from the PCV (EGR?) pipe melted the wires in that spot. When you fix it, make sure you use some good heat tape to protect it.

 

[stayalert]

Yuck!

for what its worth at least that damage is somewhat accessable. I just repaired a couple of chafed wires low on the firewall back on top of the tranny....I had less damage than you but in a less accessable area. Good luck!

 

[stuckthrottle]

err yeah, meant EGR. Sorry it's extra hot today.
Thanks for all the replies.

 

[EricE]

Its totally repairable w/o a new harness. Just separate everything and cut all damaged wires. Then match up color combos and splice back together. Solder them or but splice. It will be a lot of work but do-able.

 

[yardbird88]

Okay, I got the misfire code P0301..#1 misfire for a couple of weeks, about once a week now. Change new plug, new wires, new cap & rotor. The misfire code would come back after a week of driving after I erase the code. I figure it may be the famous melted wire harness near the EGR that everyone is ialking about. I have read a few threads & found this. Do I just open up the insulation & examine all the wires to find that #1 wire ?? Anyone happens to know the color of the wire for the #1 cylinder?

Any suggestion will be appreciated. The truck is still drivable but the CEL will comes back soon. Below are the pictures of other members for reference.

 

[AmaTX80]

I had same issue with mine after replacing wires plugs cap and rotor too. After searching on Mud, it came down to wire harness by egr. Sure enough mine had been heated enough that wires were open to elements but none of them actually melted through to bare wire. So I figured things were just getting heated enough to keep throwing that same code. I bought some heat shield tape and taped the crap out of the harness to insulate it again and then zip tied it up and back away from egr. Been great now for over a year and some hard core wheeling and Texas summer heat.

Go that route if you notice all wires are still good. Best of luck to ya.

 

[Riad]

Don't take any short cut. Buy a new harness, shield it and install it. Trust me, you will not regret .

 

[Tools R Us]

In most cases it is easy to repair the harness, resulting in a fully reliable fix. I don't solder on automotive harnesses, when vibration is in the mix, crimps are more reliable. Most times this failure is simply small spots of melted/missing insulation, so a good tape, then shield job is all that it needs.

The mount that the arrow is pointing to originally had a plastic clip that held the harness away from the pipe. They age, fall apart, if I see them gone, use a couple of large zip-ties around the harness and through the hole in the metal mount to hold the harness. The clip maybe available from Toyota?

 

[97 FZJ80]

Yes. I had to replace the entire engine harness because of it. I had RT Custom do the work on mine. He posted a picture of it about 2 years ago.

 

[yardbird88]

I don't have the 97 LX in front of me, my daughter drove it & won't be back till weekend. Is it painfull to expose the bundle of harness like removing a bunch of hoses or parts to get to that OEM heat shield wrap part?

So I should expose every wires inside that heat shield wrap to detect any defect and splice the defective wire & re-wrap with extra heat shield foil.

Will the aluminum adhesive foil for duct work do the job??

 

[robertaleon]

Here's a link to the stuff that I used: Cool Tape

Costs about $15-$20 at the local O'Reilly's or Autozone. The worst part is going to be getting the EGR off but not as hard as getting it back on! I would inspect the wires and do any necessary repairs as indicated. Wrap the bundle with two full wraps or more. Mine threw a 306 but all my wires were in tact and no problems since first wrap and second wrap while doing my HG. Technically - if you remove the TB to do this - you'll need that gasket too per FSM. $5-$8 (your mileage may vary).

Good luck

 

[AmaTX80]

I don't have the 97 LX in front of me, my daughter drove it & won't be back till weekend. Is it painfull to expose the bundle of harness like removing a bunch of hoses or parts to get to that OEM heat shield wrap part?

So I should expose every wires inside that heat shield wrap to detect any defect and splice the defective wire & re-wrap with extra heat shield foil.

Will the aluminum adhesive foil for duct work do the job??

I used heat shield tape from autoparts store. Can be found in their exhaust section. It's got a nice thickness to it and comes as a small roll, but is plenty for the job

 

[Ebag333]

Will the aluminum adhesive foil for duct work do the job??

Nope. That stuff doesn't even hold up on duct work half the time, and that's not subjected to extreme heat, cold, and vibrations.

If you want to get fancy you could use some ceramic tape, something like this:
Ceramic Tape - Alumina ceramic tape

 

[Offroads4x4]

Jeggs and Summit Racing sell header wrap tape that is rated at 2000*F. Toyota also sells exact replacement wire lenths by color code as well. IIRC.
This works great to shield your wire loom.
As far as repairs replace the burnt wires one at a time if you aren't sure which is which.

Sent from my iPhone using IH8MUD

 

[baxter650]

When i did the head gasket on our 93 i noticed that the harness covering was cooked in the area by the EGR piping.
I wrapped the area with a reflective insulating material like the blankets used for wrapping turbos and such.

 

[BigMac]

I'm with RIAD - a new and well shielded/insulated harness is the optimal solution for the long run, and unless the price has tripled in the 3 or 4 years since I replaced mine (in conjunction with HG/valve job) it is the bargain of all time.

 

[yardbird88]

The mount that the arrow is pointing to originally had a plastic clip that held the harness away from the pipe. They age, fall apart, if I see them gone, use a couple of large zip-ties around the harness and through the hole in the metal mount to hold the harness. The clip maybe available from Toyota?

It seems like the OEM heat shield of the harness is still intact & about half an inch away from contacting the pipe. I add some zip-ties to the harness & the metal clip adjacent to the engine to pull that harness another half inch away from the hot pipe. Hopefully it will stop the harness from dancing around and create all sorts of problems. I am assuming that the wires are okay inside the shield since I don't have CEL error code for a few days now.

Keeping my fingers crossed!

 

[Michael Hanson]

Wires will be corroded well beyond this area. Ditch this cable. 2 cents MIke