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Every once in a while I post this problem in hopes of finding a solution, here it is:
I have a 96 4.0L that has a delayed reverse engagement. When it hasn't been driven forward since starting the engine, reverse takes about 30-60 seconds to enage. Sometimes it engages fine. Sometimes with a hard bang or a shudder that triggers the O/D light to flash. If I shut the engine off and try it again I can usually get it into reverse fine. If I have been driving forward, then going into reverse is, but slightly delayed.
I'm stationed overseas and I have no access to a scanner to pull the trans codes. I've been told to replace the entire valve body ($613 ouch!). I've also been told to replace the reverse boost valve.
I wish, boy do I wish! In '96, OBDII made a debut and now you need a scanner to pull the codes. If you know of an alternative, please let me know. Thanks.
I finally got a hold of a scanner. I couldn't figure out how to use the snap on scanner to pull the trans codes. One thing that did catch my eye was that when the reverse failed, shift sol #1 was off. When reverse was good, it was on. Does that mean a bad #1 shift solenoid or is something sensing an error and shutting it off? Here is what I found on the scanner (bear with me):
TCC 0%
Elec Prs Ctrl 51 PSI
EPC 11.01
Trn Fluid Temp 2.38
Trn Range (v) 3.69
Turbspds (RPM) 0
Veh Spd snr 0
CCs Fault no
Shift sol 1 off (on when there is no problem)
Shift sol #2 off
Shift sol #3 off
Trn cont ind lamp on/off (flashing)
TCIL Fault No/Yes (alternating in concert with trn cont lamp:the OD lamp on the shifter handle)
Trn Ctrl Sw off
TCC Fault: no
Unfortunately, the data you posted isn't going to help. What we need to know is the specific DTC (diagnostic trouble code, in OBDII it will be a four digit number preceeded with a P like "P1870"). If the OD light was flashing then the PCM has set a DTC and you will have to read it with a scanner. Without knowing the code, you are just WAGing.
Replacing the valve body may or may not fix the problem, but that is not where I would start (I doubt that's the problem). Oh, and there is no such part as a "reverse boost valve". There is a "boost valve" in the pump but that is not your problem.
You haven't told us what the vehicle is but since you said its a '96 4 liter I am guessing its an Explorer. That means its a 5R55E automatic and the problem is most likely a band servo or accumulator leaking pressure.
Once you have the scanner plugged in and communicating with the vehicle (after entering the VIN numbers and estabilishing communications) then the main menue will ask what system. Select "transmission" off the menue and then "memory codes" off the next menue. The display will show the code numbers along with a one line definition.
You will also want to run the KOEO and KOER (Key On Engine Off - Key On Engine Running) tests.
Once you get the codes out post them here and I will tell you what they are and what direction you need to go.
Well it took a while to get a hold of that scanner again. Unfortunately, he didn't have a transmission cartridge. Here are the codes it would pull:
P0401 EGR flow insufficient
P0171 System too lean bank one
P1000 OBD II system checks inc
P0733 code def not available
P1701 Reverse engagement error
It probably doesn't help much. If anyone can tell me what the other codes mean (bad O2 sensor and EGR?) it would be a nice Christmas gift for me. Thanks!
The 0401 EGR flow insufficient usually means the egr passages are plugged with soot. The valve is probably OK.
P0171 too lean bank one means you are too lean on one bank of cylinders. That's usually a fuel delivery problem. Plugged fuel filer, dirty injectors, bad fuel pressure regulator.
The P0733 looks like a transmission code. I will try to look it up tomorrow at work and see what I can find out about it.
P1701 Revese engagement error is not one I have seen before. I will also check it tomorrow.