Hello there. Our 1996 E350 4x2 with the 5.8 and E4OD transmission won't engage drive or reverse. To make a long story short, it dropped to neutral while driving on the highway with the cruise control engaged and we had to pull it home. We have replaced the transmission with a salvage and changed the torque converter. We checked and cleaned all of the wiring harness going to the transmission that we found (the solenoid plug, the shifter range position sensor, and the plug at the top of the transmission housing where it meets the plug at the doghouse). We even had pulled the vehicle speed sensor out of the differential and cleaned it and its plug, but we didn't know more than that. I tried using an OBD-II bluetooth code reader but apparently these year trucks over a certain weight class (this is a bucket truck) don't have the capability to be read by modern readers. I also checked to see if by chance the truck still had the old EEC-IV plug to test with a meter, but that isn't there either. The overdrive light flashes on the column shifter and we tried unplugging the transmission solenoid pack to see if it would engage first or reverse manually, but it made no difference. The fluid was checked in park and on a mostly level surface. We looked into the two fuse boxes and checked the applicable fuses for such, including the PCM and they were fine. My dad and I have a reasonable amount of mechanical ability and car knowledge, and I will try to answer all questions to my best ability. Any suggestions please? Thanks.

 

You're wasting your time looking at the electronics. The only way you can lose drive and reverse is a mechanical failure inside the trans. We can try to narrow down what broke, but the bottom line will always be pull the trans and rebuild or replace it

 

The transmission was working in forward and reverse in the truck it was pulled from which had a blown engine. The problem not changed regardless of the swapped in donor transmission and torque converter. We had the whole truck pulled apart last night for the swap. From what I have pulled together snippets of information online, it seems to be pointing towards an issue with some sensor outside of the transmission. Do you have any recommendations of how to test sensors such as the vehicle speed sensor in the differential? Is there any way that the cruise control module could affect the transmission, because like I mentioned it went out when the cruise was active. What other factors could prevent the transmission from being able to engage first or reverse manually without the solenoids plugged in?

 

Let's see if I can make this clear:

THERE IS NOTHING ELECTRICAL THAT CAN KEEP THE TRANSMISSION FROM ENGAGING EITHER FORWARD OR REVERSE.

With no electronics plugged into the trans when the shifter is in D the trans will stay in fourth gear. Reverse will work.

If you installed a working trans and still have this problem then the issue is outtide the trans. I assume you would ha e noticed a broken flex plate. That leaves a broken rear axle as a possibility. Does the drives haft turn when the trans is in gear?

 

The flex plate looks fine and the driveshaft does not turn at all. We may end up getting another transmission, as the salvage one we picked up had a 30 day return.

 

There is something wrong inside that trans. It could be something as simple as not enough ATF, or it could have had a mechanical failure.