My first E4OD…what is the issue?

[BeastMaster]

The problem with a misadjusted FIPL sensor is that it causes the controller to make inappropriate shifts and not set the line pressure accurately, albeit my experience with the controller is that it is pretty good at keeping the mechanicals out of trouble by going into limp-home mode ( flashing OD lamp, really harsh shifts, as it maxxes out hydraulic line pressure ( via EPC solenoid ) trying to avoid slippage ).

Everyone seems to tell me these are pretty robust transmissions, so I wouldn't fret much. From what you have said so far...sounds like just some sensor maintenance is due.

Now, on my van, the FIPL sensor is secured by two 1/4-20 screws having a Torx T-27 head. I do not know if all use this, as I bought my van off Craigslist ten years ago. On the van, the fuel filter is in the way of getting to the adjustment screws. I used a six-inch long Torx bit and a 1/4" flex-head socket wrench to get behind the fuel filter. Adjustment is done by loosening both screws and rotating the assembly.

On my van, my FIPL sensor had a worn spot in it that kept tripping off errors. If you can get an oscilloscope or an old-school mechanical VOM ( Triplett 630, Simpson 260, or similar ), look for smooth voltage changes as the accelerator is operated. The engine need not be running, just key on is sufficient Don't leave the engine in the key-on state without running for a long time, though ( > 10 min or so ), as others here have noted the fuel shutoff solenoid in the injection pump uses incoming fuel flow as a coolant.

 

[Cubey]

I noticed something recently, hazard flashers will unlock the torque converter too, like if you press the brakes. makes sense, it flashes the bulb element that is the same for brakes. or at all it does on my van. it just keeps it unlocked, doesn't repeatedly lock and unlock with the bulb flashing

 

[ISPKI]

I noticed something recently, hazard flashers will unlock the torque converter too, like if you press the brakes. makes sense, it flashes the bulb element that is the same for brakes. or at all it does on my van. it just keeps it unlocked, doesn't repeatedly lock and unlock with the bulb flashing

Big reason why the rear brake circuit is critical to the Transmission function. The TCM sends a signal current thru the rear brake harness that is disrupted when the brakes are applied, triggers the TC solenoids to aid in faster emergency braking. Clever system, much more so than other trucks of the time...as long as its kept in good working condition, which it rarely is. This is why these trucks have issues if you change out your tail lights for LEDS. LEDs, unlike traditional bulbs, do not allow current to pass thru until that current exceeds their rated value. The signal current tends to be too low for LED tail lights and therefore, the transmission doesnt see the signal and operates under the assumption that you are braking 24/7, until some other signal is delivered to override it, such as high enough throttle position from the FIPL.

I have built a number of flat beds for these trucks over the years and this is always an issue, although it doesnt seem to make much of a difference driving around town but over long distances it could prematurely wear out the TC. All the flatbeds I have built are done with LED lights but I add a small grote halogen bulb somewhere on the back. Usually one under each rear corner to act as a sort of corner illumination. They are sufficient to carry the signal current for the TCM.

 

[OldIron82]

Well, I was able to find the contact information for my local transmission guy that I’ve known for 20 years, I always called him “transmission Jesus” I thought he went out of business over the pandemic, but as it turns out he put up his own four bay pole barn building on his own property and now he does not rent the building. He was working out of anymore.

First thing he asked me to do was take it for a ride with the overdrive off and see if it’s still acted up with the same problem. It does, so unfortunately, he said it’s going to have to come out of the truck and get on his workbench.

I believe he said a one way sprag or something like that is most likely cleaned off. I will let everyone know as things progress further.

Thank you all for your insight and help. I appreciate it.

 

[BeastMaster]

Neither of them go into neutral when the accelerator is released. As I mentioned earlier however, the torque converter does unlock and re-lock when driving at speed and letting off the accelerator and then accelerating again. If that unlock/lockup is overly harsh or there’s something wrong with the converter…..maybe it’s slipping excessively and behaves like it’s going into neutral?

Yes. The only way I know to mechanically put the transmission into Neutral is via the Gear Shift Lever, same as the other modes PRNDL.

In D, the E4OD controller is assigned the task of selecting one of four gear ratios by selecting one of the four binary states of Shift Solenoid 1 and Shift Solenoid 2. Geared down Low, geared down, Straight, and Overdrive.

Done by bands and planetary gears. Each band is applied or not. Band tension is a function of line pressure on the solenoid valving and actuator cylinders.

The illusion of going into neutral is the action of the coast clutch. It's a sprag clutch. If the engine is sped and geared to accelerate the vehicle, the clutch engages to send the energy to the tires. However should the situation reverse, the sprag will freewheel and let the vehicle coast merrily along. The shift solenoid selection continues to be controlled by the PCM(TCM) but the sprag will remain disengaged until the engine RPM ( accelerator pedal ) increases to the point of mechanically re-engaging the sprag clutch.

In order to determine which gear ratio should be selected via SS1, SS2, the PCM(TCM) needs to know how fast the engine is turning (Tach sensor) , how much fuel the driver is giving the engine ( Throttle Position Sensor ( TPS), and how fast the vehicle is moving ( Vehicle Speed Sensor - VSS ). The PCM then determines the best SS selection for the situation.

As you can see, failure of any of these three sensors will cause the PCM to make inaccurate SS estimates, resulting in harsh shifting.

I had read on a design note somewhere that the designers were well aware of the stored kinetic energy of a vehicle in motion, and wanted to make sure a failure of the transmission control system ( like shifting into first gear, full line pressure, with speed of 70MPH ) would not result in immediate destruction of the transmission, truck, driver, and surrounding traffic, so to minimize / completely avoid this predicament, the sprag clutch was designed in to mechanically disconnect the transmission in the event energy was sent back into the transmission. Remember, this was one of the first electronically controlled transmissions.

Knowing sometimes the driver needs to deliberately brake the vehicle through the drive train, means were provided to give the driver that option...the coast clutch override button on the gear selection lever ... To enable engine braking on downhill grades, as well as L1 and L2 to mechanically handle low speed maneuvers where needs of fine controllability and traditional "feel" overrides the need of fuel economy.

Remember, there was a big gas shortage going on when this thing was designed.

 

[BeastMaster]

First thing he asked me to do was take it for a ride with the overdrive off and see if it’s still acted up with the same problem. It does, so unfortunately, he said it’s going to have to come out of the truck and get on his workbench.

I believe he said a one way sprag or something like that is most likely cleaned off. I will let everyone know as things progress further.

Agreed. The transmission should conventionally brake the vehicle with the OD lockout engaged, and the little yellow LED on the gear selection lever should continuously illuminate ( same one that also serves as MIL if it's flashing - Malfunction Indicator Lamp ).

This problem could be electrical or mechanical .

I don't blame your guy for erecting his own building. Every hand that meddles in my affairs usually creates far more hindrance than help.

Especially if it's a Government Hand.

The only people I want to see is my customer and my supplier. And friends to share some bull and beer.