The computer was pulled 2 days ago for a visual and it looked fine. He brought it to town and I looked at it and smelled it and it seemed normal, but that doesn't always mean it is! I did tell him to check all the grounds, but he never said if he did or didn't. It's supposed to rain tomorrow so I'll have some time to go help him. Thanks again for the help.

 

Yea doesn't automatically mean its good but sure sounded like some damage would be evident.

One of my computers the leg of one of the caps was corroded away but wasn't noticeable with naked eye.

When inspecting it using a magnifying glass could see where the juice had leaked out of the cap down and down one leg enough to eroded away most of it but no damage to the board at that point, leg all pitted and rough looking and nearly severed rather than smooth and uniform appearance like the others.

Sounds like hes going to have to do some testing to narrow it down, eliminate one or the other, a couple of the trucks circuits or the computer...or both.

 

Took the computer out today and sent it to this guy: Ecu Repair Now, automotive circuit board testing and repair
He is going to test it and let us know.

 

Well here's a little update. NEVER, and I mean NEVER, send anything to that guy I mentioned above. My friend called him and he said he could "test" it to make sure it was bad. He called us back and told us it for sure was bad and he would fix it and put in all the "updates" so the truck would get better mileage and have more power. That should have sent up red flags with me but I thought maybe he has made some kind of new discovery. Well, a few days and $150 plus shipping later, put it back in the truck and it runs WORSE than before! What the heck! So we popped the case apart to have a look. Oh boy! I wish I would have taken a pic to show everybody. All he did was solder in new caps, but in the process he dropped solder all over the place and burned the board around the caps so bad I figured it was ruined. We cleaned off the solder splatter and looked at the work he had done. The caps were not making contact, totally missed it with the solder. So my friend, which is pretty handy with electronics, re-soldered the connections. We crossed our fingers and put it back in. Well, it runs again, but we are back to the same problems. We called the guy up to talk to him to see what he actually found wrong and he totally went off on us! Cussed at us and told us it wasn't his problem anymore! All we did was ask him how he tested it, we didn't even get the chance to tell him about the splatter and the cold solder joints! He hung up on us. We sent him a text back asking about his "1 year or 100,000 mi warranty" and he said "Warranty Void. Not my problem." We sent another requesting a refund and his reply can't be written here. So lesson learned, don't go there!

I made a few calls to friends with trucks and made arrangements to borrow a computer from one of them. The numbers were an exact match. Put it in the truck and it still does the same thing so the original computer is still functioning OK. The next step we are taking is to do some more testing on the transmission. I'm thinking a bad solenoid or bad internal wiring. We did remove and test the external harness for breaks and inspected for bad pins or connectors, but found nothing wrong. we will see how it goes.

 

Is there any way you can get a multi-meter onto a sensor 5v supply line when the truck starts acting up? That would help eliminate a power issue.

 

Thank you for the help. Power was checked for and verified, but not while it was acting up. We will give it one more check, but after that it is getting a new solenoid pack.

 

I defer to Mark for any correction as necessary but I believe reverse in the E4OD is all mechanical nothing electronic to it.
The only electrical aspect would be when moving the shifter to reverse, results in a resistor change value from the MLPS to the computer, low resistance down in 1st gear highest value in park.

You have a trouble codes for EPC, its not a huge leap that it may be directly related especially now that the computer has been eliminated.

Without looking back over the thread, has he looked over the harness for the trans, running from the top of the left side inner fender down the frame, following the cross member over to the trans?

Can be subject to damage from this or that where it follows the crossmember over to the trans.

Not good news about Ecu repair now, looked after seeing your post about them. A quick search shows they have bad reviews, have a couple of good ones but more than likely where posted by his friends.

Doesn't appear like they ever fixed a computer.


Consumer Complaints for ECU Repair Now - BBB serving Denver & Boulder Colorado

Ecu Repair Now - Auto Repair - 418 S Euclid Ave - Marissa, IL - Reviews - Photos - Yelp

Ecu Repair Now, automotive circuit board testing and repair

Some changes but the phone number remains the same!

Claims to have been in business 10 years but website has only been up for 3.

 

I have no idea if this would apply to the 94, but I have a 2002 which had a similar problem, but in reverse and drive. What I found out was that the ECU would cut cylinders as necessary to limit power when there were certain transmission error codes. The engine didn't set misfire codes because it wasn't misfiring (I mean, the ECU made it misfire deliberately). I realize on a 94 you wouldn't get that data anyway. The 2002 was designed to kill engine power in certain situations to prevent transmission damage from slipping clutches.

When the transmission solenoid power supply was fixed, it ran fine.

 

Does the truck actually die out when trying to drive in reverse?

 

I've been watching this thread since the start so I thought I'd throw my 2 cents in... Could it be something with a vacuum line somewhere or an engine electrical issue like a wire just trying to ground out when the engine torques in the direction of reverse?

 

It doesn't completely die, it stutters and bucks and misses. Now it does it in forward gears too unless you start it in neutral, then it's just fine.

 

That crossed my mind too. Went over all electrical and vacuum stuff with a fine toothed comb and the only thing I found was a crack in the tiny white vacuum line going to the heat/ac controls. Doubt that was the problem. Thanks for the ideas and keep 'em coming.

 

So now if you stay away from park it works "normally", you can use any gear forward and reverse and it runs fine?

Park position in the MLPS has much higher resistance than any of the other positions, 4100ohms for park. The next highest is reverse for 1448ohms, the remainder are lower yet,

N = 733, D = 401, 2nd = 211 and 1st = 85ohms in order from neutral down to first.

You stated it threw a bunch of codes when when started with the MLPS unplugged, but never actually stated if it would run right with it disconnected or if changing gears had any effect etc on it?

Not sure if that has a thing to do with it but wanted to mention it now that you stated it happens forward gears too and unless started in neutral. The lower resistance value neutral provides somehow effects it allowing it to start and run right?

I bring it also because MLPS and TOT both share a common circuit.

You had a "TOT sensor voltage out of self test range" trouble code, as a reminder you had stated the truck was up to full running temp when the self test was performed.

If hasn't tried it yet I'd unplug the MLPS and see what effect doing so has, gonna throw codes yea but can erase them easy enough after the test. Start it up run it throughout the shifter range drive it around some, then plug it back in to see if there is any notable difference between plugged in and unplugged.

 

When all this first started, no codes could be retrieved because of the bad MLPS. It was replaced and then codes became available. We did try unplugging the MLPS and running it by starting it in neutral, unplugging it, and then shifting it. That made no difference. But we did not try starting it in park with it unplugged by jumping the starter solenoid and then shifting it. I'm going to his house tomorrow so we will try that and see what happens. Thank you for the info and ideas danr1.

 

Yea you'll want to jumper the starter relay or the Park/Neutral safety aspect of the MLPS so you can start it with it unplugged to get a good test so to speak.
Start it without the MLPS plugged in, doing so with it plugged in then unplugging it may negate the test but jury still out on that...

Jumper the wht-pink to the red-lt blu wire at the MLPS connector, if you'd like to be able to start it with the key. (that is if my book lists the correct color code)