4l80e Swap - Reverse Grinding/Not Engaging

[alexl226]

Just finished a 4l80e swap. Used the Frost/PCM of NC (Relay) Harness. Went to back it out of the garage and no go.

Problem:
When reverse is selected, a horrible grinding noise occurs and doesn't stop until a different gear is selected.
(Best way to describe the noise would be trying to mash 1st gear in a manual transmission without the clutch, very horrible sound)

Tried:
Unhooking electrical connector on side of trans.
Jacking up rear tires, ran through N, D, 3, 2, 1. All work fine.
Went from D straight to R (with tires jacked up) and it engaged once! But only once and there was multiple attempts.
Logged current gear and when I select Reverse it flashes between 1 & 2.

Not Tried Yet:
Maxing out Trans Component Diagnostic Enable Temp and disabling the ISS.
**This is a requirment of the harness but I didnt have my computer with me, and didn't think that would keep it from completing the shift into reverse. Especially without ever driving the vehicle, would those codes be thrown? I've only read of these causing issues with auto shifting the forward gear and allowing full power...

BTW, the trans is a factory reman with 0 miles. But it was sitting in an old mans garage since early 2000's.

[alexl226]

ok, I read that hptuners shows Reverse as 2 for current gear. Why would it be flashing between 1 and 2 when I go to select reverse? Is it still trying to apply the forward gears?

[Lakegoat]

Do you have the selector lever adjusted correctly? I have the same setup except an 05.

[alexl226]

I would think I do, i logged the prnd321 and it lines up with what it should. Reverse lights come on when in reverse, neutral/park and all the forward gears engage as they should. Maybe I'm not on the same page, is that what you were referring to?

[alexl226]

update:

Got it in reverse again. With the wheels jacked up, letting it roll ever so slightly in 1 then going straight to R seemed to work a few times. It held reverse great, up an incline and out of the driveway. I drove it around the block and do not have engine braking in any gear (D, 3, 2, 1). When it tries to engine brake it seems to kick out and start making that same awful grinding noise.

Aside from that, the trans seemed to shift smoothly and go from 1-3 nicely. I tried to force 4th with hptuners, it seemed like that only fully locked the converter in 3? I saw a slight drop in rpm and a felt a little thud, so I'm assuming that's what that was.

Could someone have forgot a checkball during the reman?

*and i'm working on getting a video of the noise.

[alexl226]

http://vid37.photobucket.com/albums/...6/IMG_1902.mp4

[alexl226]

07 Stock Suburban2_Backtostock_pe2_maf2_boostPE1_spark3_4l80e.hpt

Tune is attached. All I did was max out the enable temps and disable the input speed sensor low. And use bluecats software to retune shift points and tire size. I have misplaced the bag that comes with the PCM of NC conversion harness, but I'm almost positive that's all that was required. Can anyone confirm this? With those changes it was still grinding, but I also now have a dash full of abs and stabilitrak lights. Trans is being looked at now for an assembly error, but it seems there is still some electrical issues that need addressed.

All help is greatly appreciated.

[jason k]

that absolutely sounds like a mechanical problem inside the unit parking pawl dragging? maybe a snap ring on the output ring gear left out and the splines stripping??

[Brown1jackson]

http://vid37.photobucket.com/albums/...6/IMG_1902.mp4

I'm having this same issue with my 04 GMC Sierra 2500hd. Please post anything you find out, I'll do the same

[Brown1jackson]

My problem was the input gear on the transfer case. Had it replaced and all is well