Diesel Place banner

1 - 6 of 6 Posts

·
Registered
Joined
·
269 Posts
Discussion Starter #1
Hey Guys,


Thanks in advance for the help! I will try to make this short but it will probably be long to detail the issue. Really need to get this fixed. After building the engine, etc I'm pot committed. I have searched but mostly people don't follow up with results, repairs.

-2006 LBZ Dually CC w/230k miles
-Engine rebuilt about 35k miles ago
-Trango JR with deep pan
-Edge CTS
-Idaho Rob tunes

When coming up to Montana from AZ for the summer we were triple towing (probably around 32k total weight truck and trailer). I know that's "too much" and if that is the answer to my issue I'll be buying a new truck. Truck started going into tranny limp mode (P0700) while pulling hills. I know there are other codes with the P0700 but I had to clear codes to get going again so the shop I eventually went to said they couldn’t diagnosis 100% because they couldn’t see associated codes. From reading forums, etc at that time I took the best guess and had a lift pump installed. We were down in a Walmart parking lot for 2 days so I could not do bottle test, etc. After getting lift pump installed, we had no other issues all the way to Montana. Thought the LP fixed the issue. Yesterday I drove to Seattle with a 40’ gooseneck and had no issues on the way there. Trailer is about 9k. Picked up a 40’ shipping container for a total trailer weight of 17.5k. Hit the first big hills and she limped. It was a long and miserable trip home.
I know P0700 is a tranny limp code and that it very well could be the tranny given everything I’m asking the truck to do. If that’s the case I’m fine with that and I’ll find a way to get down to Mike L. However, my hunch tells me its fuel related. I’ve never had the tranny slip it’s always been an instant limp mode while pulling heavy up hill. It only happens when I’m heavy so reproducing the scenario and then having it towed to a mechanic is an expensive proposition for them to read codes. I know it’s a big ask without having the other codes to diagnose.

I’ll plan on replacing the FPRV. I’ve read collapsing fuel hose can be an issue but that a LP would solve/mask that? So I guess my question is, assuming it’s a fuel issue what else should I be looking at if I have a lift pump and do a shimmed FPRV. Is it safe to assume that if I have a lift pump, the FPRV is replaced/shimmed, and my fuel filter housing is good that it’s the tranny?

Thanks,
 

·
Administrator
Joined
·
16,718 Posts
You need to find a scanner that can read the stored TCM code(s) to start you on the path to fixing the issue.
The P0700 is only the TCM requesting a MIL because it detects an issue.
 

·
Registered
Joined
·
269 Posts
Discussion Starter #3
I know I do, I mentioned this in my post. The issue is I'm told that because I'm clearing the CEL via my edge that it wipes the more specific codes too. I'm clearing the CEL to get going again. If I don't clear the code I'm stuck trying to limp a 18-23k pound trailer up a hill and to a repair shop all while the transmission heats up rapidly because of tranny limp mode. I only have this issue while under heavy load and up a hill.
 

·
Vendor
Joined
·
9,676 Posts
Having unknown tuning it could be

1) Slipping the trans and setting P0700 before it gets to an incorrect ratio error This should default the trans to direct drive shouldn't it? I haven't slipped a 6 speed like we used to with the old 5 speeds.
2) P0087 low fuel pressure and the DTC may not be showing due to attempts to defeat it. This would just cause greatly reduced power

Other than that its all guess work until you get known good tuning...
 

·
Registered
Joined
·
269 Posts
Discussion Starter #5
Finally got the TCM code. It was p0877. Changed the 20 pin connector seal that was leaking and the PSM and I'm still getting p0877 and limp mode intermittently while towing. Shop can't figure it out. Thinking about throwing a road flare into the damn thing!
 

·
Administrator
Joined
·
16,718 Posts
Finally got the TCM code. It was p0877. Changed the 20 pin connector seal that was leaking and the PSM and I'm still getting p0877 and limp mode intermittently while towing. Shop can't figure it out. Thinking about throwing a road flare into the damn thing!
Here is a thread on the P0877 code: Code P0877
 
1 - 6 of 6 Posts
Top