Recently rebuilt the E4OD in my '96 F250 4x4 w/460. Installed new pump, solenoid pack and Transgo Tugger shift kit.

Now the tranny wont do the 1-2 shift unless the throttle is cracked and sometimes it will jump to third. All other shifts (2-3, 3-4, 4-3, 3-2 & 2-1) are good and solid.

Tests Performed:
-air test when on the bench and no leaks
-Also tested the MLPS and all voltage and ohm values were within spec.
-pulled the valve body and accumulator apart and everything looked and moved good

Does anyone have any ideas? I'm stumped and dont want to pull the tranny back out...

 

What do you mean it won't do the 1-2 unless the throttle is cracked?

 

It won't shift out of first unless you lift off the throttle a little. If you completely let off the throttle it will go into third.

 

I'd start by getting a multimeter and measuring the voltage of the center TPS pin in relation to ground. It should be .6-1.0v at the idle stop, and smoothly increase to around 4.5-5v at WOT.

 

Thanks Lead Head. I checked the TPS and it was .8V @ idle, smooth to WOT @ 4.7V. I also pulled the codes:

KOEO - 111 (pass Code)

KOER - 311 (Air Pump, hasnt been on the truck for about 10 years)
538 (A/C switched on, A/C was actually off)

I also created an LED light bank to test to see if the solenoids were getting the signal when they were supposed to...result was Shift Solenoid 2 & Coast Clutch were not getting the signal.

while the transmission was out I inspected the wire harness and saw no signs of wear or stretching. I will inspect this again.

Any other ideas of direction to head in? Thanks for the help.

 

Coast clutch usually only engages when the O/D cancel button is activated. Sounds like you have an intermittent wiring fault between the computer and shift solenoid 2. I'd break your multimeter out and check continuity.

 

Yeah. That was my plan for the long weekend. Just wanted to see if there were any other thoughts/ideas.

 

Removed the transmission harness and throughly inspected the harness for kinks, cuts, knicks and anything I could see that didnt look right. The only thing I found was the insulation had rubbed off the wire at the solenoid connector. Fixed those areas and continued checking continuity. Everything looks good from the transmission to the Main ECM connector on the fire wall. Not exactly sure were to go from here...

I did come across a new symptom though. I was backing up hill and noticed some chatter...not sure if thats related.

Something else I found was if the battery is disconnected, for a period of time, and reconnected it will shift normally through all gears the first time you drive it. When that happened I finished going through the gears and stopped. I wanted to make sure it wasnt a fluke and tried it again. Went back to no 1-2 shift.

Very confusing and frustrating trying to get this issue solved. Any ideas would be great.

 

You may have a failing ECM (computer).
Cick this link :A9x ECM's (and same years ECM's) Failures Due to Age
I'd read the above link and remove your computer, open it up and just give it a visual inspection.
Be aware that a "visual inspection" is just that. It doesn't guarantee that a "non-visual" problem exists.

You've checked wiring and solenoid operation(s) and they all seem to be good, leaving the "control aspect" of your transmission problems to be checked.

My take,

Bob

 

Where did you tap into the harness for the LED lights?

Right at the EEC or down at the trans?

Did those Shift Solenoid 2 & Coast Clutch LEDs get the signal, light up like they should, for that first trip after you disconnected the battery and it shifted as it should?

You tested everything else and computer give it a system pass, gets a system pass because its not moving.

Sounds like the problem might be caused by the POSM, it does the the analog VSS signal to digital output conversion required by the computer to process the information it needs, so the computer knows exactly how fast the truck is moving.

How fast its moving verses engine rpm verses throttle position brakes are on etc etc. If the computer gets bad info or no info from the POSM it won't shift right or not at all or suddenly upshift more then one gear when all a sudden gets information / correct information from it about actual speed.

Problem might not be in the POSM itself, might be in the circuits between it and the computer for example.

 

I tapped into the harness at the solenoid connector.

I had taken the lights out before I found out it would shift after the battery was disconnected.

I have not checked the VSS yet. I will put that next on the list of things to do.

 

You said you inspected the harness but did you check those two circuits for continuity from the computer harness connector to the solenoid pack connector?
If you test those two circuits and find no continuity I'd first suspect where the trans harness plugs into the main harness up on the drivers inner wheel well. Disconnect it and check for signs of corrosion, those two circuits pins.




I'd check those circuits first, the fact you didn't get a light down at the trans pack was no real surprise.

Had you connected the lights right at the computer too, that would have shown if the computer was giving the command or not, then trans not getting them from that point.
That would tell you everything else was good, computer getting the information it needed, just not getting its signal to the trans coast and 2nd gear solenoids.

You pulled the trans no doubt little rough on the harness, physically test those circuits before doing anything else. Any cheap multimeter will do the job provided it offers continuity function that is. Some wire and a 12v light bulb will work too!

 

All the wires in transmission harness were tested for continuity and passed. I started with checking continuity between solenoid connector and plug on inner fender. Then worked my to the firewall while having the opposite end being the solenoid connector.

 

Ok short of a bad connection at one end or the other, kinda doubt it, that's all good.

Did you pull the VSS out of the hole, see if its got any shavings stuck to it?

Check its wires out? Test its output?

Locate the test port on drivers side inner fender, directly behind EEC test port, light green-black and pink wires.

Connect DVOM meter leads to pins, doesn't matter which way you hook up the red or black leads.
Set the scale to AC voltage 0 to 40 scale.
With rear wheels off the ground start the vehicle put trans in drive and make transmission upshift watch meter.
You must see a increase in ac voltage or VSS is bad or problem with tone ring.

Subford posts other way of testing it, verify VSS output at 30mph but do not recall the exacts.

When I did the test I put the front bumper against a large tree, if the jack dropped it (3 ton floor jack, never failed me yet but never can tell) it wouldn't go running a muck, and I had my wife in truck shifting/holding it at 30mph and higher etc. Some things are better done with little help!

 

Tested the VSS using the connector on the inner fender. At stop is was .23 VAC and steadily increased to 1.75 VAC @ 45mph. Did not pull the VSS out. I figured if it showed good voltage then theres no need to pull it out and risk damaging it.