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How common is a bad shift cable?

Did you take a file to the end of the shift shaft and deburr it BEFORE even attempting to install the NSBU? If not theres about a 98% chance you ruined the new NSBU installing it. Yes it should run in 3rd and reverse with the plug disconnected at the trans. The chance of unplugging it making it leak is basically nill. Unplugging it would not cause a leak, chances are he had a leak, so he unplugged it trying to test it for manual operation because he had a bad connection to begin with, and noticed the leak after messing with it.
 
OK, interesting issue.

Got the new NSBU installed, all went well, put it on a little, didnt want to go, took it back off, filed down a burr, try again, goes a little further, gets tight, I push a little harder, and then it slides on. I think a little filing of plastic the burr carved out wedged and then it pushed on through.

Anyways, made sure the neutral tang was still correct, everything looked good, so I tightened it down, and put the lever back on.

Fired it up, and now it will light up the indicator correctly, but when you put it in gear, it will not engage and the display will blink.

Also, when you go to put it in park, I had dad in the seat while I did it, and it will light up park, but once I lock the lever in park the highlighted square disappears.

Is it mad that the lever is still in neutral? (locked up cable still installed, need to put new one in) did I screw up the NSBU putting it on?

Or, is the tranny completely screwed?

I re-scanned it, and get the same P0700 and P0841, but now get a P2106.

What is the P2106 exactly? I looked it up and it said something like "system forced reduced power".

I wonder if that cut 2 wire harness has anything to do with this, I will snap a pic tomorrow and post it up.

Any input appreciated, thanks!
 
THEFERMANATOR said:
Did you take a file to the end of the shift shaft and deburr it BEFORE even attempting to install the NSBU? If not theres about a 98% chance you ruined the new NSBU installing it. Yes it should run in 3rd and reverse with the plug disconnected at the trans. The chance of unplugging it making it leak is basically nill. Unplugging it would not cause a leak, chances are he had a leak, so he unplugged it trying to test it for manual operation because he had a bad connection to begin with, and noticed the leak after messing with it.
Click to expand...


yep, de-burred afterwards. You know me too well Ferm. :)

I guess I go to the Allison shop tomorrow...

What does it take to un-plug the RH harness? I want to make sure this sassy bitch moves before I dump more money... and dont want to break the plug. I cant see it too well as an exhaust hanger bracket bolts on back of the trans.

I guess I have never asked Ferm, worse case scenario, what is the 841 code take to fix? is Shift solenoid C inside the valve body and a 500+ dollar reman body from Merchant should fix it?
 
Are you sure on the codes? I can't find a P2106, but a U2106 is lost communications with the transmssion controller. As to unplugging the trans plug, I've read you sometimes have to take the heat shield off to get to it. On mine it's right out in the open, but mines a swap. A flashing display means shift range inhibited on an 01-02, and is almost ALWAYS a bad NSBU. If you tried putting it on or pushed on it even remotely hard, the NSBU is most likely garbage. I did this ONE time when I did my 1st one, and learned an expensive lesson that teh plastic inside the NSBU is REALLY soft, and damages easily. Otherwise it sounds like your NSBU is adjusted improperly. When it is in park at the trans, the P MUST be illuminated, otherwise you have a serious issue, and the TCM will not allow it to go into gear AT ALL. Check the NSBU for any slack to the shift shaft, if it is TIGHT against teh shaft, then you need to readjust the NSBU, if theres any slop, you need another NSBU. If theres ANY resistance, the little tangs that lock it to the shift shaft will break off leaving it loose, and a non working NSBU.
 
yeah, unfortunately by description of the fragility, I got pretty rough with it, so I bet I trashed it. after it was on, it had a tiny bit of slack on the shaft.

I take if if I de-burred properly, it will just slide on smooth as silk?

On the RH plug, I might have to remove the exhaust support, I cant see where to release it anywhere.
 
If you can reach the plug, you just squeeze it to release it. And its gentle to get the nsbu on, force is a no no. It shoulg go on snugly, but no extreme resistance.
 
OK, had time to mess with it today.

Changed NSBU, made sure to file even more, get some emery cloth, etc. got it really smooth. new NSBU will firmly go on, I was a little concerned about the firmness, but didnt want to take alot of shaft material off.

Once it gets to the shiny portion of the shaft, it slides on easier. slotted holes are in the middle with the neutral assurance tang still installed.

Anyways, no change. :( Unlike the original bad black NSBU that would not select anything, the last two NSBUs, both tan ones from Allison, will highlight the gear selection on the dash, but will blink. in neutral it is on solid, and when you go to park, it will highlight it when you are between gears, but wont highlight it when you are actually locked in park.

So, with enough wiggling, I finally got the RH plug off, and put it in gear, and she slams into gear with full authority. :) seems to behave properly hydraulically, nice and firm.


Here are the pics of the broken wiring harness. first two pics are from the LH frame rail peeking between the t-case and the frame.

Last pic is from the back with the harness pulled out the back.
100_4666.JPG
100_4668.JPG100_4670.JPG

Think this is the issue?
 
Without that harness, she aint gonna go NOWHERE, and will most likely not even go into gear when the TCM sees an open circuit in the speed sensor circuit. It should still show if you are in park though. You need to fix that harness 1st thing as that is for your output speed sensor in the transfer case. GM used the same trans harness for 2 or 4 wheel drive, and used that extension harness to move the output speed sensor plug from the rear of the trans to the transfer case. I took that double ended plug and 2 plugs out when I did my swap, and just connected the wires together. Sounds to me like you have the speed sensor problem, and an issue either with NSBU adjustment, or shift cable adjustment for the no park being displayed. until that speed sensor is fixxed though, the TCm will not let it go into gear. And as you discovered, with the plug disconnected, it has 3rd and reverse, and shifts hydraulically at full line pressure.
 
well, that is awesome news! getting alot cheaper now. :) thanks Ferm!

So will GM offer a pigtail so I can cut and splice, or since its broke off right at the plug, should I look into buying the tools and terminals and learning how to assemble a weather pack connector? If the latter is the better choice, any recommendations on terminal and tool sources?
Or is that a sub harness that the chassis harness connects to, and I can replace it all?

As far as the no park indication, will that be due to the froze up cable not letting the lever move? (the little switch in the column for the park interlock is what actually illuminates the "P"? lever is stuck in neutral or Drive right now.

Once again, thanks!

you renewed my hope in this old gal. :) I will put the new cable in tomorrow and try to get it adjusted, then call in to GM on tuesday and see what my harness options are. at least with the new cable and the RH harness un-hooked, I can limp her around the yard. :)
 
As far as the harness goes, the junkyard is your best bet. I believe GM gets $250-300 for that extension harness that extends the output speed sensor wire to the transfer case. If it was mine, 2 heat shrink butt connectors would replace the 2 plugs and double ended connector. As to the p indicator, it receives the signal for park from the tcm via thensbu switch. If the nuetral safety switch isn't adjusted PERFECTLY, this will happen. I ended up having to adjust mine without the little holder tab to get it right.
 
on the new cable, any reason why I couldnt re-assemble it after I get the front half installed (except for actually attaching it)

THe directions in the box act like it needs to be assembled prior to install, but I am wondering if I could fully install both ends then connect, or install both ends except for attaching to the ball stud, then connect the halves, then install on ball stud.
 
Ok, I "re-interpreted" the directions, and see that they want each half installed properly, then connect it, so I did that.

Works great, and with that and the main harness unplugged, she moved under her own power today!

Full line pressure and a bad u-joint is an angry sound.... :)

I will be calling GM tomorrow and seeing what I can get for a pigtail for the wiring.

The park indicator is lit by the column switch. I can lift the lever and it goes out, drop the lever and it comes back on.

How hard is it to change the lever spring? Is there enough room in the gap to pull the old one out and shove the new one in?
 
Almost docked points from the man card for going back to directions a second time. Then I notice you never admitted to anything, so it's ok. Card intact.
 
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There is no column switch for park indication, it is all done through the NSBU on the side of the trans. There hasn't been a column switch used since 94 for the NSBU. You must be close but not dead on with your NSBU adjustment for it to be doing this. The gear indicator is run 100% off of class 2 data bus signal, and the data bus signal for gear indication comes from the TCM. As to GM, hang on tight as they will RAPE YOU DRY for those pieces. Plan on about $25 a plug, and probably $50 if they can even still get the double ended one.
 
I like the crimp and solder to bypass the plugs and heat shrink it.

Most of my trucks had the light go on and off. Doesn't hurt anything that I've found.
 
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