On the highway on my way home from an all day wheelin’ marathon my auto transmission all of sudden lost Overdrive (depressing OD button light would go on/off but nothing would happen) and the RPM’s shoot up real high like 4th gear was missing or something while I was maintaining freeway speed. I pulled off at the next exit to check things out and didn’t see any thing abnormal…linkage, leaks, fluid level, smell, or anything I noticed. Kind of late and I wasn’t that far from home so I continued on and made it home.
Next day I check it out and everything visually looks ok but now I have no reverse gear so I go back inside and review the ESM and run through a bunch of diagnosis procedures, checks, and even attach the scanner and pretty much come up empty as far as codes. Some indication point to the tranny maybe in a partial “fail safe mode” according to the ESM but that doesn’t explain the reverse gear not working or the fact I was able to maintain highway speeds the night before even at a higher RPM range.
So I tow strap the X out of my driveway onto the street with my LC and then drive it to my local transmission shop. The tech who I know pretty well checks it out for about a hour and then tells me its time for a rebuild ($700-800 parts + $600-700 labor installed) or to start looking around for a remanufactured/rebuild one which will liked be cheaper.
After a few days I find a low mileage (90) day warranted auto tranny (60k) from a recommended local importer for less than half ($500) of what a rebuild costs or a fraction of a new factory one. Figure I can do the swap myself in the driveway over a weekend.
Started out Saturday about 10am and had the whole assembly dropped by dark the same day, with breaks for lunch, playing with the kids and what not but it was a PITA and really cramped with the X on jackstands and me on my back. The bolts on the bellhousing where tuff to get out and I had to use some really long extension. Really tight in places with my big hands and you have to remove all the wiring, exhaust piping, starter, etc not to mention the suspension components, driveshaft, et although having a SAS helped in that regards. Overall took me longer that I anticipated; I was beat andsore by the end of the day so I put off the reinstall until the following weekend. Not to mention I needed to replace the rear main seal which I found out was leaking previously.
The 2nd weekend the install went a little quicker and smoother with a friend who helped out more; we had the transmission and tranny all back together in an afternoon. Filled the fluids, double checked everything and went for a spin. Hum…well reverse works so does OD and the other gears but the ATP light comes on when in P and the 4x4 one doesn’t at all…back to the ESM.
The 3rd weekend day I decided to swap my ATP and 4x4 sensors from my old transfer case to the newly installed one and install the B&M transmission cooler. Go for the test drive and now the ATP light doesn’t come on and the 4x4 indicator does so I thinking I’m all set now. Hit the highway and then the check engine light comes on and the RPM are higher than they should so I head back home thinking what now? Hook up the scanner and get a P720 code…Vehicle speed sensor error.
4th weekend day I rest the code and decided to swap the VSS from my old tcase to the new one since I know that one works and I even benched checked to make sure via the ESM procedure. After the swap the code still reappears, shifts are still off so back to the ESM for me. The only thing it might be is the revolution sensor which I find out is a magnet sensor that gets speed info from the tailshaft that is send to the TCM for shifts and ECM for diags. Trouble is it’s on top of the tranny and ESM says the tranny must be drooped to access. Damn, I’m thinking I’m cursed now
so I go drown my sorrows
and ponder what to do next.
5th weekend day I ask a neighbor with really small hands if he could access the wiring loom attached to the revolution sensor, after about 15 minutes of smoke and mirrors he manages to get a hold of it. We tape the old loom to it and pull it out though the engine bay and then he connects the old loom to the sensor. Take it for a test drive and yippe everything finally works right. On further inspect I noticed one of the wires on the loom attached to new transmission for the revolution sensor was partly damaged once we pulled it.
So what’s the moral of the story? Don’t assume sensors works even if they look newer than what you have, swap in the ones you know are good. The ESM and small hands are invaluable.
Man it was sweet to wheel and drive again after that. No more weekend's wrenching for me the rest of the year I hope.
Background: ~ 140k; I’m the 2nd owner from 120K on. PO told me regular services & fluid changes always done at recommend intervals or before and from the records, conditions of the vehicle that seems accurate to me. I changed the tcase and tranny fluid about 15k ago. Prior to the day detailed above no problems detected or noted.