Drumguy999
Member
Ok, I haven't spent much time on forums in recent years, so I'll try to keep this post concise. 2018 model year, 59k miles. I'll first describe what it's currently doing then the back story below it for those interested:
The dealer states that there are 2 wires in the TCCM harness that are not communicating properly, and the whole dash must come out to properly diag it. (i have little faith in their abilities currently, but I'm not excluding it)
Switching from 2H to 4A. From what I can tell, this seems to work just fine every time without issue, and the truck responds correctly
Switching from 2H to 4H. INTERMITTENTLY works. sometimes it shifts into 4H just fine, sometimes it gives me a powertrain fault and defaults back to 2H.
Switching from 2H to 4L. Same issue as 4H. The other night it wouldn't shift into Low but after several attempts it finally went into 4L. Unfortunately it was STUCK there for some time. I had to drive 20+ miles home and after about 40 attempts to get it OUT of 4L it finally did.
**it should be noted that every time i select a drive mode on the 4wd switch, i can actually feel and hear the tcase shift motor trying to select the proper drive. but often it will then default back to 2H, and give me a warning**
Is it more likely to be the TCCM or the wiring itself? I am unsure exactly how the wiring can be messed up, but i have not yet looked at the harness myself.
From my browsing, it seems that @FordTechOne has pretty extensive knowledge of the 4wd systems and logic maps, so I am hoping he can chime in.
Incident:
Traveling on the highway approx 65mph. I had the truck in 4A as it was wet/icy out. Everything was going along fine, and then i hit a bridge transition with ice on the other side. I felt the front end lose grip, and then felt the 4wd freak out. the best way that I can describe it was like when you hit ice and your ABS module goes crazy. But when i hit the brakes to slow down, it was not the ABS making the noise/shuddering. This was shortly followed by a smell of something burning. It SEEMED like it came from under the drivers seat and I assumed it was the clutches inside the T-Case giving up life.
From that point on, if i tried to engage 4wd (high or low), it would give me a powertrain fault, and not engage. HOWEVER, if I locked the rear diff, it would somehow force it into 4H???
Take it to the dealer (under warranty)
They diag it. Say oh, its just the tcase shifter motor. Well that doesn't fix it. Still getting powertrain fualt.
They then say the housing & shift fork is bent. they replace the housing, the shift fork, shift lever from the motor, AND the clutch pack after my asking them to. I physically saw the old clutch and there was no heat markings or evidence of burning ok weird...
New shift motor, forks, clutch, casing. physically it shifts just fine by hand. however, its still throwing the powertrain warning, and not shifting via the dash switch. They are doing all this stuff on the harness, stating that 2 of the wires are 'broken' and must have been damaged behind the dash.
A day later, they come back... tell me the wiring is ok, it must be the tccm. They then put in a new tccm with no change, still getting the warning, but stating to me that it 'sometimes' works.
Im then told it IS actually the wiring and they need to pull the dash out to investigate, but this isn't covered under warranty. At this point theyve had my truck over a month, spent days trying to look at diagrams and pin outs, and I tell them to give it back because Im done dealing with them at this point.
The dealer states that there are 2 wires in the TCCM harness that are not communicating properly, and the whole dash must come out to properly diag it. (i have little faith in their abilities currently, but I'm not excluding it)
Switching from 2H to 4A. From what I can tell, this seems to work just fine every time without issue, and the truck responds correctly
Switching from 2H to 4H. INTERMITTENTLY works. sometimes it shifts into 4H just fine, sometimes it gives me a powertrain fault and defaults back to 2H.
Switching from 2H to 4L. Same issue as 4H. The other night it wouldn't shift into Low but after several attempts it finally went into 4L. Unfortunately it was STUCK there for some time. I had to drive 20+ miles home and after about 40 attempts to get it OUT of 4L it finally did.
**it should be noted that every time i select a drive mode on the 4wd switch, i can actually feel and hear the tcase shift motor trying to select the proper drive. but often it will then default back to 2H, and give me a warning**
Is it more likely to be the TCCM or the wiring itself? I am unsure exactly how the wiring can be messed up, but i have not yet looked at the harness myself.
From my browsing, it seems that @FordTechOne has pretty extensive knowledge of the 4wd systems and logic maps, so I am hoping he can chime in.
Incident:
Traveling on the highway approx 65mph. I had the truck in 4A as it was wet/icy out. Everything was going along fine, and then i hit a bridge transition with ice on the other side. I felt the front end lose grip, and then felt the 4wd freak out. the best way that I can describe it was like when you hit ice and your ABS module goes crazy. But when i hit the brakes to slow down, it was not the ABS making the noise/shuddering. This was shortly followed by a smell of something burning. It SEEMED like it came from under the drivers seat and I assumed it was the clutches inside the T-Case giving up life.
From that point on, if i tried to engage 4wd (high or low), it would give me a powertrain fault, and not engage. HOWEVER, if I locked the rear diff, it would somehow force it into 4H???
Take it to the dealer (under warranty)
They diag it. Say oh, its just the tcase shifter motor. Well that doesn't fix it. Still getting powertrain fualt.
They then say the housing & shift fork is bent. they replace the housing, the shift fork, shift lever from the motor, AND the clutch pack after my asking them to. I physically saw the old clutch and there was no heat markings or evidence of burning ok weird...
New shift motor, forks, clutch, casing. physically it shifts just fine by hand. however, its still throwing the powertrain warning, and not shifting via the dash switch. They are doing all this stuff on the harness, stating that 2 of the wires are 'broken' and must have been damaged behind the dash.
A day later, they come back... tell me the wiring is ok, it must be the tccm. They then put in a new tccm with no change, still getting the warning, but stating to me that it 'sometimes' works.
Im then told it IS actually the wiring and they need to pull the dash out to investigate, but this isn't covered under warranty. At this point theyve had my truck over a month, spent days trying to look at diagrams and pin outs, and I tell them to give it back because Im done dealing with them at this point.
