'99 XLS OHV, TCC code, found insanely destroyed 5r55e wiring harness

[Juanhmi]

So two years ago, I bought a '99 XLS with the OHV V6 motor. For $400. 200,000 miles at the time.

I bought it in Austin, TX where I lived at the time as my first vehicle (I'm 32, but have been a bicycle commuter my whole life, go figure I buy an SUV). Carfax says it lived in Texas its whole life, ten years of that was as a government fleet vehicle, but the central Texas thing explains the absolute lack of rust anywhere. I am (I think) the third owner.

I now live in Louisville, KY, after moving up here with my dog - in the sub-$500 Explorer. It's my daily driver. I've done a lot to the truck, although it's mostly been restorative or preventative maintenance, and mostly easy stuff:

-Radiator/coolant flush
-Coil pack
-Plug wires
-Spark plugs
-Front and rear brake rotors and pads
-Power steering pump
-A/C compressor, accumulator and hoses/orifice tube (blows cold!)
-Front end work: control arms, sway bar links
-Touchscreen radio and all four speakers
-Yokohama Geolander tires
-MAF sensor
-K&N air filter
-PCV valve
-All the vacuum hoses
-Oil every 3,000 miles religiously

We're now at 230,500 miles. Just did a road trip to Austin and back to see my folks, truck ran strong the whole way and got 19-20 mpg, but I did have the dreaded P0741 torque converter clutch code and flashing O/D light come on about 500 miles into the trip. I would stop, let the transmission cool off for half an hour, clear the code and the overdrive would work normally but it would come back on after 300 more miles or so. Repeated that process a few times on the way down to Texas and on the way back to Kentucky.

That road trip was two weeks ago, O/D light hasn't flashed and the code hasn't come back, but after doing some research, I got a new transmission pan, filter, and all the solenoids, and also got a secondary transmission cooler to install, since it just seemed to be very associated with heat. I've never done a road trip in the car in hot weather like this. Based on what I've read, a fluid and filter change on the 5r55e as well as new solenoids might make things happy again, we'll see.

So, short of the transmission work I'm about to do, I was wondering if any forum veterans had any other advice for me as far as preventative maintenance or common failures. Obviously if I've gotten 30,000 miles out of a $400 truck I'm pretty lucky, but I love driving the old Explorer and I'd like to get the odometer to at least 300k.

 

[Juanhmi]

For reference. Not going to win any beauty contests, but one heck of a reliable truck for a few hundred dollars.

 

[Juanhmi]

Bumping this to the top as I'm now doing this transmission work. I had the old flashing O/D light come back this morning and decided it was time to figure it out.

Pretty easy job so far, pan and filter are off, solenoids are out. Fluid actually looks really good, nice and red. The wall I've hit now: the wiring harness between the solenoids and exterior connector is TRASHED. Lots of cracked insulation on every single wire. I'm honestly amazed things have been shifting reasonably well, but there's no way I can just pop new solenoids in and click everything back together, the wiring is coming apart in my hands. I'm relieved that my problem may have just been electrical, but now I need to acquire the wiring harness.

A replacement harness seems easy enough to find. Found another forum that mentions how to get the old one off, so I'll be working on that. My worry is the transmission input speed sensor plug that hangs down from further up in the transmission. It looks trashed too. So, solenoid harness/16-pin connector seems like an easy replacement. How big a pain is it going to be to do that speed sensor wiring? Will I need to pull the valve body down or does the trans need to come completely off?

Also, if anyone has any tricks to getting that old harness off that would be awesome. Having a tough time with it.

 

[Juanhmi]

Managed to get that sneaky wiring harness off. Can't believe the condition of that insulation. How did I just drive 2500 miles in one week with no issues?

 

[C420sailor]

ATF isn’t a conductive fluid, so unless the bare wires touch each other or the case, nothing will happen.

Definitely good to fix, but unlikely to be your smoking gun. Hopefully you find an easy fix, but your TC may be on the way out.

 

[Juanhmi]

At 230,000 miles I'd be surprised if I didn't need to just do the torque converter or find a new transmission. New wiring bits ought to be here end of this week, hoping I have an easier time of it than I thought!

 

[C420sailor]

Not sure what your skill level is, but for me the worst part is removal/installation of the trans. Once it’s on the bench, may as well rebuild it. A quality reman isn’t cheap, and a used unit is a dice roll.

I can work all day sitting on a stool, but laying under a car...the worst.

 

[Juanhmi]

Actually taking it off myself and doing my own rebuild is probably beyond my level. I'm more or less an amateur at this stuff, though I've learned a ton working on this car. At least doing this I ought to be able to put it all back together and drive away... it still shift very well with just the occasional code thrown, but I thought I'd try this as a bit of preventative maintenance. I also have a decent collection of tools but nothing I could lower or hoist a transmission with... yet.

More now than ever, I have learned that yes, if you can get it off the car and work on it on a bench, you should. I usually consider myself fairly tidy when doing this kind of stuff, but I'd be lying if I said I didn't have a head of hair slicked back with Mercon V the other day.

I keep looking at the old wiring harness and in places it's almost totally bare wires braided together and definitely touching. Suppose I'll see what happens.

 

[Juanhmi]

Case closed on this, at least for now... all solenoids and wiring harness replaced, fluid and filter changed, and so far (only 50 miles in), no O/D light or other codes, all gears and overdrive working. Probably just bought myself some time on such an old 5r55e, but sure was cheaper than a rebuild.

 

[C420sailor]

Niiiiiice

 

[Cstoliker]

I can’t believe you picked that up for $400. The bush guard alone is worth a few hounded!

 

[Juanhmi]

I can’t believe you picked that up for $400. The bush guard alone is worth a few hounded!

I did add that myself after the first year of driving, too terrified of deer in Texas and Kentucky.

 

[Cstoliker]

I did add that myself after the first year of driving, too terrified of deer in Texas and Kentucky.

I have the same problem with deer up here. So I made mine battle ready. Light bar and bush guard

 

[96eb96]

Rust free truck like that here would win lots of beauty contests. And would find an owner in days.

 

[Juanhmi]

I realized pretty soon after I moved from Austin to Kentucky that if I ever buy a used car again, it will be back in Central Texas or somewhere similarly dry. My beater truck is a '91 F150 that I bought here in Louisville and it loses half a pound of metal or so every time I drive it.

 

[Mr. Alligator]

@Juanhmi

did you ever figure out what caused the deterioration/destruction of that wiring harness?

Rats/mice???

 

[Juanhmi]

I assume heat and time. Then again, this truck lived for 200,000 miles without me as the owner, and I've only ever put Mercon V in the trans for 30,000 miles, but who knows how well it was taken care of. It's worth noting, the transmission pan that was on there when I bought it had a hole drilled in it and one of those rubber wingnut plugs, so someone did a halfass job of changing fluid at least once before. When I did this job I replaced the original pan with an aftermarket pan that has a real drain plug.

 

[Juanhmi]

Unfortunately, resurrecting this thread. My solenoid job and fluid and filter change got me another few thousand miles and then another long trip got my TCC code coming back and my O/D light flashing. So, not wanting to get rid of the truck since the rest is in good condition, I took it into a shop with really good reviews and got a remanufactured transmission put in.

Drove home from the shop today, in a great mood to have the car back, didn't get much over 45 miles per hour... flashing O/D light comes back to haunt me, same old codes. Although generally the truck's driving amazingly better and no longer making a host of horrible noises that apparently were from the old trans, I might be crazy but I felt like the shifting got harder when that light began flashing.

I've been doing this long enough to know that I need to complete a drive cycle after the battery is unhooked for awhile, which is what my mechanic recommended I do over the weekend when I called him, and of course I do have the P1000 code coming back that indicates that's true. I'm having a hard time believing just clearing the computer with the battery off would cause a TCC issue though. Maybe somebody forgot to plug something back in? I'm pretty amazed to be having the same symptoms with a new transmission.

 

[Mr. Alligator]

Was the deteriorated wiring replaced?

Maybe you had two issues.... transmission AND transfer case.

What is the pattern of the O/D flashing.... six flashes separated by some time?

Good luck, and I am sure you will resolve this.

 

[Juanhmi]

The wiring issue on that original transmission was the internal harness connecting the solenoids in the valve body. The external wiring is original. I'll have to recreate the O/D light flashing and double-check, but I'm fairly sure it's a steady flash... but I may never have stared at it long enough to notice six flashes and then a delay.

I just took it out on the highway on a whim to see how it would perform faster than 40mph - started blowing some serious smoke after a few minutes, smelled like transmission fluid. Pulled over and let the engine run for a few minutes, then drove the shoulder to exit the highway, got home with no more smoke.

I'm really hoping it was just a messy mechanic getting a bunch of fluid all over my exhaust and not something leaking, although I suppose it could also be a messy mechanic overfilling the trans and having fluid fly out the vent tube all over everything once things got warmed up. Neither option is making me very happy with the shop I chose right now.

Old transmission, performance was bad all the time, worse once the light started flashing. New transmission, performance is excellent - until the light starts flashing.

My paperwork from the shop shows cooler lines were flushed, so I'd think I can rule out overheating.