P0bfd
 

New code came up tonight while my wife was going down the interstate. Running at 75-80 yukon shuts down and will not restart for about 5 minutes. Drive 5 minutes same thing happens again. We finally got off the interstate and let it sit for 20 minutes and it starts up and drives home. Pulled the code and had a P0BFD

Re: P0bfd
 

Current sensors went out on Motor A.. was that the only code??

disconnect the 12v battery to reset the computer make sure the connections are tight


COPY THE FREEZE FRAME data for future reference first



https://cimg1.ibsrv.net/gimg/www.gre...9e506af48f.jpg

Re: P0bfd
 

it have the general hybrid fault P0A4F or whatever it is. I cleared it with the scan tool and pulled all of the hybrid leads from the engine side to check them. Maybe one want seated as it should be. I am going to take it to work tomorrow and see if I can get out to happen again. I didn't pull the freeze frame data, don't really know how to with torque.

Re: P0bfd
 

Check the orange wires going from the inverter module to the transmission for damage. If one or more of the phases is shorted to ground, that code will pop up because the current in all 3 phases is not equal.
Earlier hybrids had an issue with possible pinching of the cables to the frame. Make sure this did not happen. Unplug from the inverter module (after disabling the battery) and measure resistance from each wire to chassis ground (this will test for internal short). Then disconnect from the transmission and test from each wire to the shield. But since it drove home, it is more likely the issue is the orange harness. Disconnect from both sides and test from each to its shield.

PIP4374C: Hybrid Inspect Transmission Three Phase
Cables For Adequate Clearance To Body - (Dec 7, 2018)

Customer may comment that the service engine soon light comes on and the vehicle is a no
start.Technicians may find various codes including but not limited to DTCs P0BFD and or P0BFE.

The above condition may be caused by a damaged or rubbed through 3-phase
transmission electrical cable.
Visually ONLY inspect the 3-phase cables from under the vehicle. The cables can be viewed near
the transmission bell housing on the passenger side of the vehicle.
There should be a minimum of 1/4 inch (6.35mm) between the cables and the body pinch
weld.
If the clearance between the cables and the pinch weld is insufficient or the cables are damaged or
dented the 3 phase cables will require replacement.
These cables should ONLY be replaced by a qualified Hybrid technician. Do not attempt to
straighten the cables to add clearance.

Re: P0bfd
 

Those are the ones I just reseated in the engine compartment. They got push/pulled/moved every which way when I dropped the transmission.

Re: P0bfd
 

Looks like one is touching the pinch weld. 😢
https://cimg6.ibsrv.net/gimg/www.gre...1d3840b96.jpeg

Re: P0bfd
 

Yikes! Look at it on the bright side. Now you know the cause of the problem and what needs to be done to fix it (or prevent it from coming back). You can separate it from the pinch weld (maybe a split rubber hose piece around the orange cable), but to guarantee you wont be left stranded in the future, you need to replace it with a new or known-good used harness and come up with a way to prevent it from touching the pinch weld in the future.

Re: P0bfd
 

Going to let yall know that I got the code cleared and the power line fixed. I glued a piece of rubber hose to the punch weld above the transmission, filled in the cut on the power line leading to the transmission (only one had damage) with silicone, and wrapped that line in rubber hose as well. I was also able to move the lines back to where all of them are at least 1/4" off of the transmission and pinch weld area.

I am mainly paying this in case anyone else ever has to remove or replace the transmission from a Chevrolet Tahoe or GMC Yukon hybrid. I guess I could have done a YouTube video on it but the only real difference from a 5.3l is the 6 power lines on top of the transmission and the lack of a starter attached to the engine.

Thanks to all of you for the help in diagnosing my screw up. 😁

Re: P0bfd
 

Those six(6) cables going to the transmission are coaxial. There is an upper section where orange non-metallic insulation is covering braided shielding. Then the transition to orange anodized aluminum tube shielding.

If that outer aluminum tube punched through the inner insulation, it may have been the short detected.

Hopefully you removed the "dented in" portion so a new short can not happen

Re: P0bfd
 

@hillbilly the metal jacket on the line was just barely worn through. I didn't try and bend the hole back out but did use rtv silicone in the hole. My thoughts were to insulate inside the tube by creating a silicone layer between the wiring and the metal housing. I assume the housing is grounded on the engine bay as well as the transmission side, so if there is voltage leaking out it will short and cut the engine off, as it did with my wife driving. So if the rtv didn't fix it I still have a chance of getting stuck on the side of the road. If that happens I guess I'll be buying another line (or 6) and replacing them.