First the acronyms:
- TECA, PCM, TCM: these all refer to the computer. TECA is transmission electronic control assembly, PCM is powertrain control module, and TCM is transmission control module.
- TECA relay: Referred to as the EEC relay by most autoparts stores, it switches power to the TECA and sensors when the key is on
- VSS sensor: Vehicle speed sensor. 91 and older it's located on the trans tailshaft with a cable going through it to run the mechanical speedo. 92 and up use the rear ABS sensor, sometimes referred to as the VSS sensor at autoparts stores
- FIPL: fuel injection pump lever sensor, also referred to as the TPS (throttle position sensor) by autoparts stores. It tells the computer how much the throttle input is
- MLPS: manual lever position sensor. It's also referred to as the TRS (transmission range sensor) and it tells the computer what gear is manually selected (PRND21)
- Tach sensor: located on the timing gear cover, indicates engine speed to the computer
- TFT: transmission fluid temperature sensor, it's part of the solenoid pack
- SS1: shift solenoid one
- SS2: shift solenoid two
- TCC: torque converter lockup clutch
- CCS: coast clutch solenoid, controls the coast clutch to allow some engine braking on deceleration *See MLSC's post below*
- BPS: barometric pressure sensor, indicates altitude to the computer
- EPC: electronic pressure control solenoid, located in the solenoid pack, controls shift firmness.
- PSOM: programmable speedometer/odometer module. On 92 and up it converts the rear ABS signal into a VSS signal for the trans. It's also the speedometer as it is attached to the rear of the speedo gauge.
The most handy piece of equipment to have is an old style Ford EEC-IV code reader, or an newer code reader that can hookup to the old style EEC-IV diagnostic terminals. Codes can also be read with a test light or a multimeter. If your trans is acting funny the first thing to do is get the codes! The second thing to do is remove and replace the connectors on the trans, clean off any corrosion. The problem could be as simple as a bad connection. If there is no automatic control then either the trans isn't getting power, the sensors aren't grounded at the pass. side battery, or the solenoid pack is burnt. In my case metal sendiment from miles of trans issues settled on the solenoid pack circuit board and shorted it out. It doesn't hurt to pull the pan not only to check condition of the fluid but to do a fluid and filter change. If you do it wouldn't hurt to unbolt and remove the solenoid pack and give it and it's connector a good cleaning.
Now just throwing sensors at the problem can get expensive so again it's best to get the codes. 92 and up used an upgraded MLPS and the connector is different, most parts stores will sell it with a pigtail connector or a new connector body that the terminals from your old connector snap into. If this is bad all sorts of things can happen, no OD, no converter lockup, dropping in and out of lockup or gear, etc.
There are posts all over this board about the FIPL, make sure you have the newer grey style. IIRC it should be 1.1 ohms in the closed position and no more than 4.5 ohms at WOT. This is meaured by sticking a probe on the middle wire and the other to ground, then manually move the throttle from idle to full slowly looking not only for min/max but also bad spots in the range.
The VSS signal tells the trans when to shift as well as lockup the converter. If it's bad or open the converter may not lockup and the trans takes forever to upshift, almost like it's slipping. I believe a bad tach signal can do the same thing.
If your trans is shot try to get one appropriate for your year. I bought a 94 trans to go into my 91 van and found that there is not a gear machined into the tailshaft for the VSS and cable speedo drive. I was able to get around this by rigging up a PSOM from an 93 van and outputting it's VSS signal into the original trans harness. I had to completely remove the trans harness and install the updated connectors for the solenoid pack as well as the MLPS. The end result however is a trans that shifts really nicely. I also have a 99 4R100 trans with a driveline parking brake, my brother confirmed it has the gear for a cable driven speedo in the brake housing. It was also confirmed elsewhere on this forum that that trans is the same as a 4x4 trans if you remove the driveline brake and install a transfer case. I believe that most transfer cases have the provision for the cable speedo drive.
My future plans include hooking up a manual TCC switch that will give me locked, unlocked, and normal. I'll post more on that later. I also plan on a large trans cooler with an electric fan and a trans temp gauge as I often do heavy hauling. Eventually I'd like to rebuild the 99 4R100 if it is confirmed it will fit this van and do a 4x4 conversion. Especially since I've got a front Dana 60 waiting for me to pick up. I'd also like a torque converter setup for towing and the appropriate shift kit.
If you are experiencing harsh shifting, funny shifting or no shifting, please check the codes and the appropriate sensors and connections first. Don't let it go unfixed. I am certain letting it go destroyed my original transmission.
I hope this thread helps as many people as possible. I am no expert but i have learned a lot in the past few weeks from trial and error, the forum, and wiring diagrams from the library. I have also learned that the E4OD is one heck of a stout trans and should live a long time if everything that supports it is kept properly maintained. I admit I was very frustrated with it at first, seemed like a lot of complexity for an extra gear and a locking torque converter but once you understand how it works it's rather simple really.