I bought this 99 Expedition 4x4 with the 4.6L hoping for a quick fix. It only had reverse no forward movement at all. I took the 4r70w out and replaced the broken parts and the burnt forward clutch. I installed the transmission and now it goes into first and second but just keeps climbing in second won't shift into third at all. Manual 1st then 2nd is better as in D it will climb in 1st and not shift in 2nd. When in 2nd if I shift into D it will go neutral. I know the computer is not original and it looks like it has a different EGR. No check engine codes. Overdrive button works. Its not in limp mode. Checked pressures are good at test port and direct clutch port. Not sure what to check next. Anyone have any ideas?

 

After rebuild problems can be tough to diagnose because most of the time its builder error and that leaves the door wide open for just about anything.

I am not sure I understand what the transmission is doing based on your description, it sounds like you just dont have 3rd and 4th gears or maybe not shifting at all in drive but has manual 2nd.

Are you sure your scanner can read transmission codes? most small handheld scanner wont. Data would help catch things like the speed sensors, the MLPS switch and computer commands.

If the transmission is shifting and will shift from first to second, will it eventually shift into neutral by itself? If so this tells you all the shift valves moved and the problem is with the direct clutch.

I would start with the valve body, go through it thoroughly making sure the check ***** are correct and the valves move freely. You can air check the transmission with the valve body off, key on the direct clutch apply.

 

Thanks James for your knowledge. So to be more clear on what it's doing. I can manually shift from first to second no real problem kind of slow to engage second but that's the least of my problems with this thing. Once in second it won't slip into neutral it just keeps revving higher. If i put it into drive while it is revving in second it goes into neutral. Now if I start in drive it will keep revving in first and won't shift into second until I manually shift into second. I already took the valve body back off and checked all the valves and check *****. Blew everything out and made sure everything was all clean. The only thing I didn't remove and clean was the EPC solenoid I just blew it out as best as i could because I didn't want to disassemble the linkage for the shifter. I'm trying to figure out what is suppose to happen when it goes into 3rd and see if by the symptoms i can figure it out. I pretty well know the transmission inside is good unless the band's are not engaging or maybe the overdrive servo is leaking which by researching seems to have been an issu with this transmission. I'm a troubleshooter at heart so figuring it out is part of the fun. So any input is appreciated.

 

Still sounds like it just might not be shifting out of first automatically.

When you start off in drive it pulls in first with no shift to second then you select second and it manually shifts to second and you speed up. Then when you shift to drive it downshifts to first and over revs because of your speed.

Can your scanner read trans codes and have option for data for the transmission, it would be helpful to know what the computer is doing.

I would not worry about the EPC right now, they are pretty tough.

 

Yeah your right about that it's not upshiftng unless i manually shift from first to second but when I'm in second and Put it in drive it's not dropping into first and revving because of that it just goes neutral. It revs while giving gas but let off and it drops like in neutral would. The scanner i have says it reads transmission codes. So if it's not upshifting at all what would cause that? I have noticed there are allot of things replaced on this truck like a different main computer for one and it has some electrical things that are screwy. The odometer sometimes works but most of the time it's either blank or just going crazy like it's shorting out.

 

Ok so I'm thinking about what you said that it sounds like it's not shifting and because there are no error codes what could cause the computer to not know it's time to shift? So I'm thinking how about the speed sensors? If they don't send the signal that the truck is moving then the computer won't shift the transmission right? So I check for signal voltage at the transfer case and there is none. I check the pcm and it's been replaced and it's for a 2 wheel drive so I'm thinking that may be the issue. What do you think?

 

First get the right computer. If the vss isn't being received by the pcm then it will never shift right. The pin outs n the 2wd pcm may not be the same as a 4wd

 

They are the same. The difference is that the two wheel drive vehicle never grounds the pin that tells the PCM it's in 4x4 low because there is no transfer case and no transfer case sensor.

If that were the problem the truck would always shift in high range, which is 4x4H and two wheel drive. It would not upshift in 4x4L.

 

I'm thinking the vss to be the problem. I'm trying to figure out what all goes on before the pcm signals the transmission to shift and how no signal to shift could happen without throwing a code. Mark's right the pcm is the same for the 2 and 4 wheel drive it's just flashed different I've come to find out. Where I'm at now is I removed the speed sensor at the transfer case ohms are around 5 Mega ohms don't know yet if that's good but it's hard finding good wiring schematic's and in depth troubleshooting procedures that i can do with a multi-meter. I'm going to figure out the PSOM circuit and see if that may have a problem too. The odometer has that cracked solder pin I think because it has that flashing on off mixed up display showing up. I sure can't wait to figure it out though it's going to be a nice truck once it finally hits third gear! Any ideas and comments are greatly appreciated. Thanks guys

 

When you repaired the forward clutch how far did you go into the trans? Was it completely torn down and every part inspected? Whenever I see a burnt clutch 9 times out of 10 there are other damaged parts. The only thing that changes on 2-3 shift is the direct clutch comes on. The forward and intermediate stays on and the intermediate one way overruns. So if the direct is not holding it will stay in 2nd until OD is commanded then it will neutral because in OD the forward is released and the OD band comes on. I have seen stripped splines for the stub shaft, broken welds in the drum, and ripped seals with good clutches that all can cause direct not to work.