I picked up a 1990 Bronco with the E4OD in it.. The guy that I got it from took out the stock 8.8 rearend and put in a 9 inch. The transmission shifts hard and late and the speedometer dosent work. The ABS light is also on because of the rearend swap.. What would cause the hard shifting?

 

Where is the output shaft speed/road speed pickup coming from? PCM needs shaft/road speed to properly shift the E4OD. I am guessing that without this input, the PCM goes to a crude default table of values to drive the shift solenoids.

 

Edit note:

Okay, at least I caught myself.

For years 93/94+ the following is pretty much the case, not so much the 90.

One link for reference. Speedo cable in the transfer case on 90? See first response on this thread for reference. https://www.ford-trucks.com/forums/1...different.html

sorry about the bad post info though..

Nick


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Torky is on the mark. The 8.8 rear end originally had a sensor sticking out of the top of the differential (VSS = Variable Speed Sensor.. I think) which read from the internal tone ring. The VSS generates a signal that is used by the PSOM (programmable speedo odometer module) and, perhaps not surprisingly, the Antilock brake.

As I understand them, the Ford 9.0 do not come with either the VSS or the Tone ring and would require modification to retrofit. I'd be surprised that yours had been modified, pleasantly, but surprised none the less.

Do some searches for VSS, limp mode, hard shift, PSOM, etc., you should find plenty of references. Be aware, there are many causes for the speedo to not work (PSOM) including a too long screw in a dome light. (Fuse 18 & 8... don't ask how I know)

See what else pops up, but were it me, I'd probably be looking to do something else with that 9". There's lots to be found in tech threads on axles.

Nick

 

so simply put, install an 8.8 rear diff back in the bronco and your problems will go away.

 

Find someone that wants that 9 and can give you an 8.8 with the VSS housing. And of course, make sure the gearing matchs the front. That's probably the cause of the speedo/E4OD not working properly. I any case, check that the 9 hasn't been modified to accept the VSS, then you'll be looking at a different issue.