I believe this is a self inflicted problem but I'm lost. We'll start at the beginning.....

I just rebuilt my 46RE transmission including new solenoids and speed sensor. I took it for a drive and it has the classic starts in 3rd gear but goes into second if you shift it manually issue. I got under the truck to make sure everything was hooked up and I found a round 4 pin plug hanging at the rear of my transfer case with nothing to hook up to. The truck has a 1996 transfer case in it with a speedo in the tail shaft but that is a 3 wire plug.

Question #1: does anyone know what that 4 pin plug is for?

I eventually gave up on the 4 pin plug and started investigating my tcc wiring and relays to make sure they were good. The relay checked out fine, i even swapped it and still had the same problem (all the while I have no codes at all). At this point things went down hill.... I tried grounding out the wire to the transmission solenoids and must have grounded the wrong one, it made a small spark and all of the sudden the O/D OFF light came on. Once that happened I started checking fuses to see which one blew but they all checked out good. In the process of checking the fuses I had a lapse of judgement and pulled out fuse #11 I believe "ignition FD" while the truck was running. The chime started going off so I put the fuse back in and the chime went away. (all the while the truck continued running). I shut the truck off and now it will not start again.

There is no spark now and the cel is on. The odd thing is that before all this happened I could cycle the key 3 times and get the codes on the odometer. In it's current state, the on board diagnostics are not functional, it just has an illuminated cel. I went back through and re-checked all my fuses and they are all still good. The asd relay clicks when I turn the ignition on.

I have tried disconnecting the battery. The CEL goes away but all it does is crank, then eventually the light comes back on. I'm at a loss here and I don't want to break anything else. All insight is appreciated.

 

Can you beg/borrow/otherwise acquire a reader? See what the PCM is whining about?

That rear sensor is the output speed sensor. PCM needs that to decide what gear trans should be in. Without it, it goes into limp mode.... and starts out in third gear....

What happened to your original T-case?

 

I'm not sure what happened to it. I just bought this truck. I havent been able to find this sensor to buy anywhere. All I can find is the white one that goes in the transmission and the one for the rear diff. Anyone know where I could buy one?

 

On your truck, stock, there wasn't one back there at all, just the one in the side of the trans. (I think.... drivers side, toward the rear of the O/D unit) Truck gets its cue for the speedo from the sensor on the rear axle. Real possibility nothing plugs into the back of the T-case at all. (but then, it is also quite possible, since the pic in the service manual is for 2wd, the sensor moves to the tailshaft housing on the t-case for the 4wd....)

FSM simply calls it "Output Speed Sensor." Might see if you can look up one of those.

 

Ok that makes sense. I still need to figure out where that round 4 pin plug in my trucks harness goes. I pulled the code and its P1389 "asd relay voltage"

 

Not getting the right voltage OUT of the ASD relay. That powers the coil, and fuel injectors. Bad relay?

 

After some more investigation here's what i've found. I swapped the ASD relay thinking that was it and still no start. I figured out that 4 pin plug I was concerned about is for an oxygen sensor. The previous owner took the cat and down stream O2 sensor out and the wire is just hanging there now. Being back at square 1 now with the transmission I have another question.

I replaced all my solenoids with upgraded "HD" solenoids. The kit I bought had the round plug for the gov pressure sensor and the wires going to the round plug that goes in the trans case were different colors than the one I took out. The Gov pressure sensor and torque converter lock up unit I took out of my truck had the 4 blade flat style connector. Was there a major change in the solenoid wiring from 99-00 and perhaps I got the wrong kit/wiring and that is causing my problem? But if that were the case wouldn't the computer be screaming?

 

I have found my problem, or at least part of it. The Grey connector on the PCM had a colossal melt down. It melted the pins on the board to the plug and once I pried the melted plug out of the socket, 5 of the pins pulled out of the board with the plug. So it looks like i'm in for a new computer and plug. Hopefully the computer was causing my transmission issues too and all will be resolved with a new unit.