I'm new to the forum here. I have had ongoing problems with this. It all started back in August. I changed my fuel filter and the next day I started my truck and got the dead pedal and low pps input code. I cleared and all was fine for a few weeks. Then it threw the code again so I replaced the APPS. Its the one under the battery. It didnt fix the problem so I took it to a shop who said the ecm was bad and replaced it. It was fine until January when It threw the APPS code again. They said the ECM was the problem, not the APPS. So they warrantied the ECM. Same thing happened again two weeks later. Warrantied the ECM again saying it wasnt the APPS. Two weeks later it happened a third time. This time I took it to a dealer for a second opinion. They said it had a bad APPS, changed it and all was fine for about two weeks again. It then threw the APPS code again. I found the APPS plug was loose so I plugged it back in, drove it that day and all was fine. Then then next day it threw the code again but it wasnt simply a loose plug again. Took it to dealer which said the APPS was bad and that something is wrong with my wiring harness and they need to replace two pieces of it. This is 2000 dollars worth of parts for the two harness pieces plus labor. Has anyone had this happen to them and was it indeed the wiring harnes? Any info/advice would be appreciated. I did tell the dealer to give me all the old pieces they take out so I can look them over and look for bare spots etc. Figure if I find any then I can reinfoce those areas on the new harness. But what if it isnt the harness? If the ECM is good and the APPS is good can it be anything else? Batteies are new and the cables and grounds are good and clean too.

thanks!

 

Did I post this in the wrong section? Thought there would be some replies by now.

 

Sometimes it takes a little time. Don't get frisky.

 

I had an electrical issue similiar to yours and went thru the APPS replacement thing (which it didn't help by the way...) and I had lost OD. Just one minute it was there and the next morning it was non-functional. Go figure. Took three weeks of troubleshooting, hitting the boards, asking shops, etc. then I took the cables off the batteries, bought 2 cans of contact cleaner and commenced to spray and clean every connector on the ECM, the PCM (The three plug ins where it's located on the pass side firewall area) and the APPS. Do this multiple times, plugging them in and disconnecting them to get a lot of friction on the connector pins and thus cleaning the microscopic corrosion off them. I did it like 6 times to each connector and then blew them off with the air hose before reassembling. I used a little vasaline on the tip of my finger to lube the seals on the connectors at the final assembly.
As of this date (some 170000 miles later) I've had no more issues.
There was a tech TSA on these plugs as well where a recall said the dealers had to inspect the cables and plugs and make sure they had good o-rings aroeund the plugs. I think it was referenced for the PCM issues.
Anyway, saw your post and knew you'd be waiting for a reply. This is just what I ran into, and it might give you something to do while waiting for another reply to your dilema.

Here's the link to the TSA and it's post #5
https://www.dieseltruckresource.com/...d.php?t=242216

 

The truck is at the dealer having two sections of harness replaced. They said that there is two harnesses between my apps and the ECM. I think the auto trucks had 3 or 4 pieces. Mine is a six speed. Hopefully any problems with connections will be resolved by replacing the harnesses. Is this a common problem? If starting to think it is from finding other posts.

 

The dealer called yesterday and said the wiring harnesses are definitely the problem. Had one plug melted almost completely in half and a few more that we're in very bad shape. Sound like I've had a voltage spike at some point in time. What can cause this. I've already cleaned all grounds and battery posts and replaced the batteries. Anything else could cause this? My alternator always charges at 14.9 volts. It has gone to an even 15 volts a couple times but not more. Any ideas? I'm glad I found the problem but would like to make sure it doesn't happen again.

 

These kinds of problems are created by corrosion on the pins of connectors. This is normally caused by the ingress of water (seal failure). Once the corrosion occurs, the connection becomes resistive, which causes voltage to drop across the corroded connection. This causes the pin(s) to heat, which causes more corrosion and more heating etc 'till total meltdown.

 

Well, the truck is ready to pick up tomorrow. They replaced what I am believing to be all three pieces of harness in the APPS Circuit. Am I correct in believing that will fix all this? ECM is pretty new and checked out ok, APPS is new, All wiring harness is new, and batteries/battery cables are new. Grounds have been checked and cleaned. Anything I'm missing here? I cant keep having the same problem every two weeks anymore... If anyone has any other ideas please let me hear them. I really want to get at least another 180,000 out of it.

 

Picked the truck up. It made it home. That's a good start. Lol. Seems like as I accelerate through the gears that when I press the clutch and let off the accelerator the engine is slow to idle down. Don't know what to think. Any ideas?