PRND321 underline issue

[2004LB7]

It's a GM part. Where is the other end of the plug located? Does it go straight to TCM? Does someone have a schematic or can point me in the direction? Hard to meter wiring without knowing what's what.

Thank you for the continued suggestions, guys

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[JoshH]

Here is a little more info on the operation of the NSBU switch:

NSBU Switch Range Chart
Range	A	B	C	P
P	OFF	ON	ON	OFF
R	OFF	OFF	ON	ON
N	ON	OFF	ON	OFF
D	ON	OFF	OFF	ON
3	OFF	OFF	OFF	OFF
2	OFF	ON	OFF	ON
1	ON	ON	OFF	OFF

 

[ieetgluu]

Here is a little more info on the operation of the NSBU switch:

NSBU Switch Range Chart
Range	A	B	C	P
P	OFF	ON	ON	OFF
R	OFF	OFF	ON	ON
N	ON	OFF	ON	OFF
D	ON	OFF	OFF	ON
3	OFF	OFF	OFF	OFF
2	OFF	ON	OFF	ON
1	ON	ON	OFF	OFF

It's looks like that's the pinout for 01-04(2 plug) , which is awesome, but I need 04.5-05(single plug). Is the tcm plug pinout also different between the two?
Thank you

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[ieetgluu]

If the TCM C2 pinout is the same 01-05 then I can use that with the LLY Engine Controls schem. that 2004LB7 posted.

All good stuff, guys, Thanks

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[ieetgluu]

At first I thought this was gibberish lol, then I looked harder and separated it out

Given that D321 are all messed up, I'm guessing the issue will be on "C"


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[JoshH]

At first I thought this was gibberish lol, then I looked harder and separated it out

Given that D321 are all messed up, I'm guessing the issue will be on "C"
View attachment 126382

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That was my thought as well.

 

[JoshH]

Sorry, for some reason I thought you were working on an LB7. Maybe when you mentioned your early TCM, it got me mixed up. Here's a pinout for the newer style LLY NSBU.

 

[ieetgluu]

Sorry, for some reason I thought you were working on an LB7. Maybe when you mentioned your early TCM, it got me mixed up. Here's a pinout for the newer style LLY NSBU.

Download fails each time I tap on the pdf . I'm guessing tapatalk issue

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[2004LB7]

Download fails each time I tap on the pdf . I'm guessing tapatalk issue

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Worked for me, so probably Tapatalk

 

[ieetgluu]

Thank you

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[ieetgluu]

Troubleshooting nsbu wiring end to end was on my list of things to do this weekend. However, I hopped in it yesterday and the dam thing is back to normal. Was good again today, for now. It's been getting cold overnight here in New England lately but getting into the 70s this weekend. Can't imagine that having much of an affect.

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[ieetgluu]

Troubleshooting nsbu wiring end to end was on my list of things to do this weekend. However, I hopped in it yesterday and the dam thing is back to normal. Was good again today, for now. It's been getting cold overnight here in New England lately but getting into the 70s this weekend. Can't imagine that having much of an affect.

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Finally got around to figuring this out today. The issue lies within the Tapshifter harness, that Ive now removed. This harness sits between the factory red plug harness and the tcm. When I metered each pin of that harness I found pin 7 range switch signal C the only one to not have some sort of continuity. This is one of several wires that go through a circuit board covered by a piece of heat shrink around it. I didn't open it up yet, but I assume some crusty green death involved.

Glad I thought to check this before crawling under to check the truck harness end to end.

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[ieetgluu]

I had expected to find the wire for C rubbed through somewhere on the truck harness as it's common to all of the shifts I had an issue with D321.

NSBU Switch Range ChartRange.
A. B. C. P
P OFF ON ON OFF
R OFF OFF ON ON
N ON OFF ON OFF
D ON OFF OFF ON
3 OFF OFF OFF OFF
2 OFF ON OFF ON
1 ON ON OFF OFF

Oddly enough, when I started it yesterday it was losing the underline on all shift points, but would occasionally underline only park. It would shift rough between PRND just sitting in the driveway.

Removed this guy today and it's back to normal.


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[TheBac]

What did you remove? There's a lot there to be so vague.

 

[2004LB7]

Is this some kind of aftermarket module installed?

 

[ieetgluu]

What did you remove? There's a lot there to be so vague.

The Fleece Tapshifter got removed, shift lever and harness. That pic was the harness, loom cut open, showing the 'circuit board' some of the wiring goes through.

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[ieetgluu]

Is this some kind of aftermarket module installed?

Yes. Tapshifter adds the +/- shift button that the 06+ has. This is on my 04.5 lly

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[TheBac]

Thanks for specifying what you removed.