markwt

Hello, I am sure if your on this forum you have had as much problems with your 04-08 f150 disaster.


I have an 2004 f150 fx4 with 5.4, auto trans with O/D. I am experiencing Trans Fault error and flashing o/d light immediately at start up. If it does nor come up right at start I am fine, transmission works perfect, never has come on while driving. After trying many things I decided to replace transmission instead of throwing money at old trans which has 118k miles. With transmission replaced I was still experiencing trans fault. I figured it must be in the computer so I replaced that, still did not fix the problem. I then replaced the transmission wiring harness, still had problem. I them figured that maybe there was an internal electrical issue inside new trans, I replaced the through case connector and also hard internal wiring harness, once with an aftermarket, then again just recently with a Ford one just to be sure it wasn't an aftermarket issue.


I have researched endlessly and cannot figure it out. Weird thing is that when it was warm out I had trans faults, when it got cold I did not have one trans fault all winter, had a few 70 deg days, was fine in the morning when colder but when warmed up got trans fault back, which is what triggered my decision to thinking it was temp related and maybe the TFT was malfunctioning and replace with Ford hard internal harness.


Does anyone have a sequence of operations to process map that truck goes through to prove points before it starts. It is something definitely electronic because trans works perfect when I do not experience trans fault. Any help is more appreciated that you could ever imagine.

BadFish523

Nope my F150's have been great! Sounds like you're just throwing money at it without trying to diagnose anything. Might as well continue throwing money at it!

BadFish523

Sorry that was rude of me. There is TONS of reading that can be done on this. Do you have and Edge tuner? Are there any codes saved? Whats the fluid look and smell like?


https://www.f150forum.com/search.php?searchid=12737982

markwt

Stephen, no big deal I get what your saying. I have tried everything I have read both on service manual and every post I have seen on this topic. I have tested components, tested continuity on wiring, etc. I do not have an edge tuner, only an OBD2 scanner. The bad part is that I am not getting any codes when it goes into trans fault, I used both of my OBD2 scanner, same result. Maybe the edge tuner will provide more codes? If I drive it in trans fault I will eventually get O2 sensor fault codes, both on sensor 2, both banks. The fluid is almost new, looks and smells good.

BadFish523

Wish I could help. I'm not much help when it comes to transmission. Just wanted to post what was already found on here and hope it helped. The reason I asked about the Edge tuner is some have said the tuner was causing the trans fault. Hope someone else can chime in with better luck. Not sure what would be left since you replaced the trans, the PCM, and the wiring harness. Did you get the PCM flashed when you put it in? Does the truck have the latest updates flashed to it? Just a thought but I don't know if its a good route to go.

markwt

I bought the PCU online and they said it did have the latest flash. At one point I eve sent it back to they to test it to make sure everything checked out and they said it was fine. I may have the dealer flash it to be certain the PCU is not the issue. Most everything I have read is people experiencing Trans fault after over heating and burning fluid, or it happens while they are driving. Mine comes up as soon as I start it and has never come on while driving if it did not come up at start up.

techrep

iTrader: (1)

Have you had a transmission shop look at it ?

markwt

I have not. Besides all the research, testing, and replacing parts I have personally have done, I have only had it back to the mechanic that installed the rebuilt transmission. They cannot figure out what is causing the issue either.