Neighbor needs (transmission) help 94 F250

[MountaineerGreen]

Some vehicle info first:

94 F250, 5.8 EFI, Auto Trans (E4OD I think), 2wd

The problem:

Has been fine up until today, was driving down the road, AMP gauge pegged out, truck started acting up. Battery cooked and was replaced on the side of the road. Alternator was replaced, truck runs fine, but now has some electrical issues, and the transmission won't shift. The wipers now come on when the breaker is in the fuse panel regardless of stalk switch position, but the breaker blows quickly. I suspect the multi function stalk thingie went nuts with the power surge.

The other major issue is the trans won't shift out of 1st. Runs fine, but won't shift. It appears the E40D is electrically controlled to some extent, but I can't figure out what does it. This is where we really need some help. What module controls the trans?

 

[Tbars4]

...just some input here but i had this happen to one of my f250's...it was actually the positive side cable to the starter and it started a fire between the battery and the starter out of the clear blue...the reason i say this is you may have that cable or another positive wire grounding now after heating up and creating a new short....i myself would be doing some more wire check and trace before i fried something else...just my .02 cents...

 

[MountaineerGreen]

Back for an update: the trans, manually shifted, will go into second, but will not pull in 3rd. I don't know diddly about these, is the trans controlled by the ECM on OBDI systems?

 

[MountaineerGreen]

Anybody?

I have spent hours looking and reading, I guess I assumed other sites would be close to as informative as this one, boy I was wrong. I can't find diddily on Ford truck forums, not much technical info available.

I am thinking the PCM controls the trans, but the MIL illuminates when the key is turned on, the motor runs fine. Can a PCM go bad only in one portion?

 

[Tbars4]

...a major electrical short like the one he had, can do that...nothing can fry circuit's quicker....there is nothing worse to trace either....have you tried to pm glacier or brooklynnbay about the tranny???

 

[MountaineerGreen]

No, I haven't PM'd them- I hate to bother them, I am sure they get lots of requests for help. I guess I shall though.

 

[MountaineerGreen]

bump- trans still no shifty

 

[TedJ]

The E4OD is electronically controlled according to the service manual. If it is the E4OD, there will be an O/D on/off switch on the end of the shifter.

E4OD Automatic Transmission

The E4OD transmission is a fully automatic, electronically controlled, four-speed unit with a torque converter clutch. The main operating components of the E4OD transmission include a torque converter clutch, six multiple-disc friction clutches, one band, two sprag one-way clutches and a roller one-way clutch which provide for the desired function of three planetary gear sets.

Transmission gear selection in the (D) range and converter clutch operation is controlled by the EEC-IV control system. Operating conditions are relayed to Powertrain Control Module (PCM) (12A650) by various sensors throughout the vehicle. The powertrain control module compares these conditions with electronically stored parameters and logically determines how the transmission should operate.

In the (D) range, automatic operation of all four gears is possible. The transmission control switch lockout switch, located on the vehicle's shift lever disables overdrive operation and enables automatic operation through the first three gears. Whenever the ignition switch is turned on, the vehicle will automatically provide overdrive operation regardless of the switch position the last time the vehicle was running.

Manual gear selection is available in the 1 and 2 range. Second gear is commanded when the gearshift selector lever is in the 2 range and when downshifted into the 1 range at speeds above approximately 56 km/h (35 mph) (for diesel 48 km/h [30 mph]). First gear is commanded in the 1 range at start-ups and when downshifted into 1 range below approximately 56 km/h (35 mph) (for diesel 48 km/h [30 mph]). Any reference to Intermediate Brake Drum or Direct Clutch Cylinder are one and the same.

-Ted

(wiring diagrams coming soon)

 

[TedJ]

I would start by checking all the wiring for melted portions and that none of the battery cables have been messed up (ohm them out, don't trust your eyes) A major over voltage can blow out just about anything....Check the grounds on the trans, ecm and solenoids

-Ted

 

[MountaineerGreen]

Since the trans works in 1st and 2nd, manually shifted, and was fine before the "meltdown", I'd suspect a short somewhere or which ever module is the controller for the trans. Does the PCM control the trans on this truck? I assume it does, since it monitors trans fluid temperature and modifies shifts accordingly.

If that is the case, why could the engine run fine, but the trans not shift?

Assuming no shorts exist, is the PCM the likely culprit?

 

[Tbars4]

... i think you are on the right track as it being a short and affecting the trans...that is why the engine would run fine but not shift....a major short will overload the weakest electrical it can find and then to the next one...it is probably in one of the modules and that is why you can't find it...again, i would hit glacier up as he can point you in the right direction of which module...
....tedj has given excellent info and i do understand myself, not knowing the simple workings of one item can be frustrating as heck...

 

[BrooklynBay]

Have you dropped the pan to check the internal wiring harness for the solenoids? It's possible that the problem lies in that area. Another thing you could do is test the connections on the PCM going to the transmission. An EEC-IV break out box would come in handy at this time.

 

[MountaineerGreen]

I haven't dropped the pan, didn't even think of that. An electrical surge could mess up the internal wiring?

It is OBD1, so I am going to jumper the test port, read the codes and see what it says.

I jsut can't see how a PCM could be partially fried

Oh, and I don't know if its related, but since the surge, the speedo doesn't work, its buried at the high side and doesn't move.

 

[BrooklynBay]

It sounds like there is no electricity going to the transmission, or possibly the circuit is open so the PCM isn't receiving any input from the sensors, and solenoids.

 

[MountaineerGreen]

I guess we will spend some time this afternoon following the wires around and looking for burnt or melted wires.

My neighbor is a really nice guy, it seems like bad luck just follows him around. He doesn't have much money to work on his truck, I don't have much at the moment to help him. This is his only vehicle for his whole family of four including two young children, so he needs a running, functioning vehicle.

 

[TedJ]

You need to be looking at the VSS and instrument cluster. The solid state portion of the cluster SENDS VSS SIGNAL TO PCM. If the cluster (which is one of the more electrically sensitive things) is not working, then the will be NO signal to the PCM. The truck can't shift w/o a VSS signal. Don't do anything else until the cluster / speedo is working...

If the speedo did not work at all, then I would say that it might be the sensor or wiring, but since the needle goes all the way up, then that would seem to be a internal problem with the cluster. It relies on a frequency counter to read the signal generated by the VSS, and there is no B+ connection in the sensor portion of the circuit (so i doubt that fried). I would think that only an internal problem could cause the needle to go up. There could also be a problem with other things as well.

This pothead kid at my old school was trying to jumpstart his car, and reversed the cables. We replaced the coil and ignition module to get it to start, and then later he had to replace the alternator, b/c it would drain the battery (fired diode pack). Automotive electrical components are not well protected for over-voltage/reverse polarity. His ECM was ok though...

I had to delete the other wiring diagrams b/c my upload space was filled... If you need them back lemme know.

-Ted

 

[snoborder42]

I know that this may sound simple but my dad has the same drivetrain in his f150. Have you checked the fuse in the panel inside the cab. I don't remember exactly which one it is but, There is one fuse that controls a ton of things, including the electronic shifting of the tranny, the speedo, interior lights and many more things.

 

[MountaineerGreen]

We checked every fuse individually, none were blown, but I will recheck them.

The instrument cluster may be the thing- the speedo needle is maxed out at all times, never goes down. If the VSS feeds the cluster, then the cluster feeds all others, then that may be the thing.

Is the Programmable Speedometer Odometer Module in the cluster?

Thanks for the input, I really appreciate it.

 

[TedJ]

Yes I beleive that the module is part of the cluster. The VSS (actually the rear abs sensor) does not produces pulses (what the PCM wants). It produces AC voltage in much the same way a generator does. The frequency (and voltage) varies with the rpm of the axle (ground speed) The circuitry in the solid state part of the cluster takes this AC voltage and measures its frequency, which is equivalent to a certain speed, and converts it to a pulsed DC signal, and sends that on the the PCM. So it does not just send it on, it electrically converts the type of signal that is sent into the unit.

Is the ABS light on? The way the system is set up, The ABS system gets signal before it reaches the cluster and is converted. The abs system is not necessary for the cluster to get the signal, but it will tell you if the sensor is high resistance etc. I don't know if a lack of VSS signal to the PCM will set a code...

-Ted

 

[MountaineerGreen]

The ABS light is on.

So, do you think replacing the cluster with a junkyard model would be worth a shot? My neighbor works long hours, its their only vehicle, so long troubleshooting times or complete down time is unacceptable.