Torqueshift with TR sensor DTC's.

[Mekanik]

I'm working on a 2008 F550 with a 6.4L and a Torqueshift. This started when I rebuilt this transmission. It was previously rebuilt by another tech who replaced the reverse clutch. Somehow, the needle bearing behind the reverse planet came apart. I replaced the reverse planet carrier, sun shell, and ring gear with the reverse clutch. At this time there were no DTC's, it just had a bad noise.

 

I get done with the transmission and it works great, no DTC's. Everything is great until the wrench light comes on and it downshifts into a lower gear. This is 230miles after I rebuilt the transmission. The only DTC I had was P1702 for TR circuit intermittent. I went through the pinpoint and tested the wiring from the trans to the TCM and everything was fine. I put a TR sensor in it and it seemed good. There wasn't any metal in the pan, so that was a relief.

 

One week later, the truck is doing the same thing. Only now I also have a P0706 and P0707 in addition to the P1702. These are TR frequency fault and TR low input.

 

Has anyone ever run into this before? I really don’t think I could have pinched the harness inside the transmission. I did take a look at that last week.

[Mbl35]

Could the TCM be faulty?

[Keith Browning]

My personal experience with these types of failures has proven to me that the hard parts in the transmission are not the problem. What screws us up is when we "just had the trans apart" that has us thinking like that. I would agree that this is likely a harness issue. Start with the things you touched or disturbed such as the internal harness and the connector at the case. My experience has also been that these modules rarely ever fail and since the truck didn't originally come in with this problem the odds are it's something you touched. I am probably serving more as a cheerleader at this point...

[Brad Clayton]

[Mekanik]

Yes, I took a very good look at the bulkhead connector going into the transmission and found a connector pin that was pushed back. Earlier when I checked the wiring, I was looking at my pids while wiggling the wiring and connector. I guess some times we just need to take things apart (again) and take a very close look.

 

Thanks for standing on the sideline cheering for me.

[Keith Browning]

I have seen my share of transmission harnesses on gas powered Soooper Dooodies laying on the right exhaust manifold. No matter how little damage it looks like the harness is always junk. From under the truck you might notice it laying there but because it has heat shielding around it you cant see the cooked wires inside. The harness usually has chafed through, but if you don't move the harness and look at it closely you might miss it. I even tried repairing one by splicing in new sections of the damaged circuits. What a waste of time.

 

Glad to hear that you gound your gremlin.

[Mekanik]

What you said in your first post was very logical and good. It's hard to think like that when your upset about the truck coming back for the second time, with the looming possibility of having to take the transmission apart again. Thanks again!