Hello!

Just recently rebuilt my E4OD out of my 1995 F350 with a 7.3l 4x4, and after a few drive-cycles it began not going into OD intermittently (some days it would go into OD), and now after doing some 4x4 snow driving, the truck starts in 3rd gear, and does not shift out of it during driving. I can manually shift to 2nd gear, and that functions as intended.

Troubleshooting:
1. I verified my solenoids actuate on the bench when I had the transmission apart, and physically saw the valves move in the solenoids when triggered.
2. I verified the harness with the solenoid bank unplugged is getting 12v, and that all pins are seated in the connector, and none are broken on the solenoid pack.
3. I can hear my TCC solenoid click when I use my TCC lock up switch wired in my dash (so I know it's getting 12v). But the TC is no longer locking up. I was able to lock up my TC using the switch prior to this right after rebuild. Why is the solenoid triggering but not locking it up now?
4. When it functioned normally after rebuild, sometimes 1-2 would give a harsh shift if at high engine speeds (this also happened pre-rebuild, and I noticed I had a broken spring in 1-2 accumulator body piston, so i'm surprised this hasn't changed much - solenoid pack related? Seems like it slips for awhile and then hammers it on. Solenoid related?).
5. Speedometer works with no drop outs.
6. Brake lights work.
7. OD switch does not flash, but verified bulb in it works, and goes out of OD as intended when pressed.
8. Fluid level is correct.
9. During Key-on, if I plug in the Solenoid connector, I hear 1 faint click and a humming sound if I hold my ear to the pan. This means something is getting 12v, but If i recall correctly, I thought I heard multiple solenoid clicks when you connect the plug when I tested it pre-rebuild. Is this correct?
10. No codes stored (used ForScan). Maybe I should go drive this at length and see if one populates?

Parts that I reused during the rebuild:
1. Solenoid pack
2. Accumulator body that I pulled off of a 97 F250 gasser from the junk-yard but modified all sections with the superior kit springs. The original one looked like a Sonnax part, but the steel line pressure piston was mangled from the back and hard to remove.
3. MLPS switch.
4. Valve body in general.

I really just replaced seals in all pistons, clutches in all assemblies, bushings, and the TC, and replaced the accumulator body springs with a superior kit (somebody already rebuilt this thing awhile ago with a superior shift kit, it seems like).

I haven't dropped the pan either to check if I screwed up installing something in the casing, and I followed the Transmission Bench videos closely. The truck seemed to drive OK in all gears up until this point besides the harsh 1-2 shift, and i wasn't hearing any grinding or strange sounds.

Any help is appreciated.

Thank you,

 

How did you determine it is in third gear? When the solenoids are not powered the trans defaults to fourth gear, and manual second gear is available when the shifter is in 1 or 2. This matches what you have, so I highly suspect the solenoids are not getting either a power or ground signal.

 

Well, I thought 4th gear was overdrive, which normally puts me at 2000rpm @ 60mph with the TC locked up (4.10 rear end ratio, 33" tires), and my engine speed was closer to 2600 @ 60mph (although I don't remember the exact range since it's been a few days that I drove at that speed - I can re-check). It seemed like 3rd gear to me, but am I understanding this incorrectly to begin with? When i calculate the engine speed, it should be 2600rpm based on my specifications.

If they aren't grounding, and there is continuity to the PCM (not sure if Ford calls it the PCM - whatever controls the transmission), has the PCM been known to fail in this way?

Thank you,

 

It is rare for the PCM to fail. Usually, the problem is an open circuit in the wiring harness.

I don't know of a way for the E4OD to fail into only third gear. I suppose if the shift solenoids failed with both in the third gear position, or the shift valves failed in the third gear position, but both of those involve multiple failures that have to happen at the same time. Same thing for the PCM. For to fail to third gear it has to have multiple failures where it is holding one solenoid on and one solenoid off. Very unlikely.

It is much more likely that the wiring harness has some damage and has two or more open circuits.

 

Fair enough - thanks for the feedback, and I'll keep digging.

 

Ford post



Hello, some updates:

• checked the harness for open circuits, short circuits, etc, and no issues found. and re-loomed it with stuff I had laying around.
• Modified the harness to output led indicators for the solenoids (will do arduino + digital number readout later, for fun)
• Modified the harness to accept manual solenoid actuation.

Here’s a video of a drive after cold-start of the LEDs lighting up.

LEDs top to bottom:

1. Solenoid 2
2. Solenoid 1
3. TC lock up solenoid

For those interested:

Solenoid 1 ON = 1st gear

Solenoid 1 + 2 ON = 2nd gear

Solenoid 2 ON = 3rd gear

Solenoids OFF = 4th gear




I just wanted to verify the PCM is actually commanding them correctly during driving, and it seems to be. In the video you don’t see the TC lock up led illuminate, but it does after it’s a bit warmer, and seems to work fine.



Looks like the problem lies either with the solenoid pack or valve body…unless something in the casing assembly is causing this issue, which I’m not sure.



I’d like to try manually actuating the solenoids first during driving with switches before I pull the pan.

 

Great job building that diagnostic tool. It really rules out the ECU since it's commanding the transmission; the transmission just isn't responding.

 

Problem solved.

Old main valve body had a bunch of chips in it and some cracks that I didn't notice before (so maybe some valves were sticking?). Replaced the that with a good condition part off ebay, and has been shifting well and functioning properly the last few weeks.

Valve body casting was fine too - checked it for straightness with a machinist straight edge, etc. I was worried about putting the check ***** back into the valve body casting upside down, but ATF paste saved the day.

Thanks for tuning in everyone.