I have been having problems with the tranny in my 89 F 250. No tach reading, will not shift. If put into drive I get what feels like 3rd or OD being shifted into 1st is the only way that I can get first gear then moving manaly though the gears 1st ,2nd nothing, drive 3rd or OD. I have replaced the tach pick up and checked the other sensors with no change any ideas?
Second question I know the history of early E4ODs and this one is showing signs of needing a rebuild in the near future. How hard is it to put a C6 out of a 86 6.9 into a 89. I know this may seem like im going backwards but this truck is manly used for towing and making short hauls here and there so losing OD isn't too big of a deal for me.
thanks for any help with this.
Jason

 

Are the tach and speedo working as required......

 

The speedo is working fine. the tach guage itself seems to work but it is not getting a signal.

 

This almost sounds like a dead or dying PCM, but it could just be some bad electrical conections.

With no computer imput, the E4OD will default to 4th gear when placed in drive.

How does the initial engagement feel (ie, from P to R, or N to D)? rough, soft?

I actually went from a C6 to an E4OD to get the overdrive, so it can be done, if you want to swap to a C6, but I wouldn't throw away the E4OD just yet.

 

I would almost say the engagements are soft. I tried to pull the codes but the computer gave me no codes at all. like the ECM was dead I checked power going into it and power on all the right pins.

 

No codes at all, did the scanner detect anything at all? I think the system should show a code even for normal operation.

It sounds a lot like a bad PCM to me, although in theory it could also be bad shift solinoids, but that wouldn't explain the dead tach. Oh, and the speedo for 1989 was cable driven, so even with no power at all, it would still work.

Did it all happen at once? Are there any other issues with it that could shead some light on the problem?

 

About 3 weeks ago I started up the truck only to find that I had no tach and the tranny would not shift. Replaced the tach sensor and checked all the contections nothing fixed it. Last week I started up the truck and I had a tach again. The truck shifted fine. Sometimes you would have to wait 30 secs to 5 mins after starting before the tach would work and the tranny would shift. That lasted for about 2 days now its back to no tach no shift

 

No codes at all like the PCM wasnt there

 

I think I'm going to call this one as a bad connection somewhere. I think its unusual for a PCM to partially fail, then come back to life, I think its more likely to be a bad contact in the harness some where.

The most likely place for corrosion is at the bulkhead connector that powers the solenoids at the tranny, its the only conection on the passenger side.

Be carefull when plucking it, it has a stupid setup that locks it in.

First remove the heat shield, then press the tab on the outer side of the connector in while pulling up on the harness (you may have to wiggle it around to get it to pop out). If you use a screw driver, you will just break the plastic.

If you find corrosion in there, it can be repaired with a replacement connector, as long as its not too bad on the tranny side.

You should also check the main connector at the PCM itself, and any other connections in the harness, chances are that if its a bad contact, just disturbing the connection might be enough to get things working again.

If that is indeed the case, you may want to get some electrical grease to protect the conectors to prevent future problems.