Exhaust went Super Nova? (1 Viewer)

[crtx]

Hey all, I purchased a 2000 LC with 204K on the clock. Sat since 2016 or so. Cranks, but does not run. I am in the process of getting it up and going. Came across some interesting findings, and could use some recommendations.

Situation:
I was in the process of tracking down an electrical gremlin that is causing the 15A GAUGE fuse to blow instantly when ignition is keyed on (driver side fuse panel). I have been visually inspecting every wire and plug, checking for signs of where the wire harness was damaged, molested by prior owner, rat chew, water damage, etc.. Wire harness is pristine in the engine bay and cab...

I pull codes to see if any are stored, and OBD2 port spits out a P1760 code: "Linear solenoid for line pressure control circuit malfunction". Hmmm. I crawl underneath to inspect plugs around the trans, and come across this:

The plugs on the side of the trans visually appears though they were a wax candle, and burned. Wires, loom, and plugs all along the left side of trans are heat damaged. Wire harness running on upper left side of trans - also melted/ fused together.

The brake line fastner on the side of the frame - also melted like wax :

Its clear the wire harness experienced some impressive amount of heat from the catalytic converter... which is most likely plugged.

Questions:

1. How would you approach fixing this? (attempt to repair wire harness from scratch? Replace harness completely?
2. What other damage would you be inspecting for?
3. Could the transmission be internally damaged due to this amount of heat? (in reference to the P1760 code?) Or is there a chance the damaged wires are making the ECU throw the P1760 code?

 

[crtx]

Did some more digging, appears there are 3 plugs tucked away on back Side of engine (above red line). From bell housing back is one wire harness? This may make complete wire harness replacement a more appealing option.

Part number circled I believe is the one I am looking for, based on my 2000 year, wire harness could be 82125-60380?

Area heat damage occurred:

 

[Zer0zg]

That could 100% cause your codes. I just replaced mine for corrosion problems and had intermittent and various codes(though not that one specifically. Mine is slightly different as I have an '04, but I found a clean used harness on eBay for $70. Your part number looks right, though was superseded by 8212560382. I'd just buy a new/used harness, your connectors AND wires are shot so you're basically starting from scratch anyway.

Hard to tell which connector that is in the the wax photo as your connectors are different than mine, but if it's the internal trans harness you'll likely need to replace that as well unfortunately. Another part I had to do on mine. Messy job, but not hard. PN 8212560310 I believe. Do a trans fluid replacement while you're at it.

If it's the temp sensor that should be an easier time. PN 8942934010, but either way I'd be taking a VERY close look at anything plastic in the vicinity. Put new fluid in it and see where you stand.

 

[2001LC]

Easiest would be to replace harness. 98-02 was different transmission than 03-07. So likely we've at least 2 different harness in the 100 series. Toyota does sell wire blocks and pigtail, if you decided to rebuild.
Use your VIN # here or call a Toyota parts department, to get correct PN #s.

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[crtx]

Update on this situation - GAUGE fuse blowing has been resolved. It was indeed due to burned trans harness due to hot exhaust.

Only code I was receiving via OBD2 port was P1760 code. Upon visual inspection, heat damage was found to wiring harness around driver side exhaust.

After removing the damaged transmission harness, and keying on the ignition, the fuse GAUGE fuse still intact.

Now that harness is removed, I am getting codes PO0753, and PO0758. (I mention this as it might be helpful for others in the future that get this code, first thing I would check would be the plugs on top of the bell housing. There are 3 of them. Accessible from top of engine, looking down backside.

Here is image of plugs, when removed from vehicle.

Here is complete transmission harness when pulled from vehicle:

Damage to the transmission harness:

 

[Zer0zg]

Update on this situation - GAUGE fuse blowing has been resolved. It was indeed due to burned trans harness due to hot exhaust.

Sounds about right. I’d expect at least some trans codes even stationary with no harness plugged in at all.

 

[J1000]

I'm guessing cracked exhaust manifolds > exhaust leak > cat melt down.

 

[crtx]

I'm guessing cracked exhaust manifolds > exhaust leak > cat melt down.

Thats a good idea. I will inspect the manifolds as well.