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Discussion Starter #1
Started the truck up at work one day, about 5 seconds after starting it put it into D. The shift indicator just flashed at me. The transmission didn't engage any gear. Shut the truck off, started it, put it in D. Same thing, flashing gear indicator, no engaged gear. After a few cycles of this truck finally engaged in drive, and drove fine.


Since then on about 50% of the starts on the truck and engaging reverse or drive I get a flashing gear indicator or the normal lit indicator with what feels like one forward gear only (3rd).


Thought might be the NSBU. Bought a new NSBU, installed it. Cleared the PCM P0700 code. Truck drove perfect for two days, now it's back to the same symptoms. Upon starts about a 50/50 shot at getting a proper gear engagement and normal performance or getting the flashing indicator with no actual selected gear or the one forward gear only.


I noticed on the NSBU that the mounting holes are elongated. I've also read I believe here on this very board about adjusting the NSBU. Though I haven't seen an specific procedures on adjustment/calibration. Anyone think this may be the issue? Like with a throttle position sensor there are reference voltage ranges for open and closed operation. Is there a way to do such calibration with monitoring the PCM sensor outputs? I don't have a way to interface with the TCM.


Thanks for any helpful tips, tricks, or thoughts.Edited by: Derek M
 

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Derek,

It is possible adjusting it will cure the symptom.
The new switch comes with a thin stamped steel alignment strip that is designed to facilitate proper orientation.

The idea is the alignment strip holds the switch "innards" in the nuetral position.

You remove the old switch. Then you put a wrench on the shift rod coming out of the trans and rotate it to neutral by counting detents. Once you are sure the trans is in neutral you install the new switch with that metal strip still in place. Install the two mounting bolts and tighten.

THEN you remove the alignment strip.

If you didn't do all of the above than it's just a little trial and error. Get under there and loosen the bolts and rotate the switch some. Tighten and test. If it gets worse, try the other way. That's how I did my friends and it worked great.
 

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Discussion Starter #3
Thanks Hoot, I'll try what you stated above when I get home. I wasn't aware of the procedure you stated when I installed mine. I installed the new NSBU while in park, thus I had to turn the NSBU to get it properly oriented with the keyed shaft that protrudes from the Allison.


Again I'll try that tonight and post any updates from there.


I almost wonder if my old NSBU is still good, just was on the edge of being properly aligned.


ThanksEdited by: Derek M
 

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I'm sure you are, but for anybody else doing it a reminder - put the parking brake on.


Steve
 

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Discussion Starter #5
YZF1R, Yep doing the parking brake and chalking the wheels at the same time.


Didn't have much time last night at dusk to do the proper NSBU alignment per Hoots recommendation. I loosened the two retaining bolts, turned the module to center the bolts in the middle of the elongated mounting slots, and called it good. Cleared the P0700 code from the PCM when for a drive with several stops, turn off the truck, and restart sequences. On my 20 mile commute this morning there were no issues. We'll see how this goes through the weekend.


If I get any flack from the truck again I'll do the proper NSBU alignment per Hoot's recommendations.


At this point I'm not sure if my original black NSBU was bad or just slightly out of proper alignment.


ThanksEdited by: Derek M
 

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Hoot; this may sound like a dumb question, but can you just put the trans in neutral before you take the old NSBU off ??





Jomar
 

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Jomar





Yes ....


Ya you guys don't get rund over ....That would suck ...


Mac
 

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Discussion Starter #8
On Saturday and again I Sunday I got a brief second of a flashing gear indicator as I put the truck into gear from park. Though this was only a brief second, after that it engaged in gear fine. Monday driving home, took off from a light and the truck only had 3rd gear. The SES light lit up soon after this.


Got home and pulled the NSBU off got the metal alignment strip in place and reinstalled the NSBU, only to find that there's now slop in the key'd plastic. I believe this is because of me taking it on and off two or three times. Upon doing some testing over the past couple days only thing to note when going from park to drive the indicator light doesn't make it all the way to drive, it goes blank over the N and requires for me to pull the shifter just past the D position as so to get the indictor light show's in the D position. Other than that self induced slop in the key'd plastic I haven't had any drivability issues.


Yesterday I picked up another NSBU. Since now I'm a little smarter on the installation thanks to you guys I hope it goes on and performs without a hiccup. I should have time to install it and will keep you guys posted.


Thanks
 

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Sorry, to steal info, here..... What is the NSBU switch? And what does it do. I was told the Allison has a sensor on it, that will melt. Same thing?
 

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Discussion Starter #10
NSBU is the Neutral Safety Back Up switch. I don't have the specifics on the switch but its physically attached to the gear shift cable and rod that extends from the Allison. It appears that it's a way to electronically convert the physical gear selection into something the PCM or TCM uses to manage gear selection functionality.


Installed the latest NSBU last night. Drove fine last night, drove fine this morning. Something odd that I noticed with this NSBU that the gear selection indicator when shifting between gears has constant illumination of the gear your moving from or to. I was noticing with my self damaged NSBU is that when transitioning between gears the indicator would actually go dark, then a fraction of a second later it would illuminate the gear you selected. This was pretty consistent when shifting up and down the whole range. Again the NSBU I just installed consistently performs without these blackouts as you transverse between gears. This also seems like the functioning I had previous to any issues.


So far so good. Will report back in a couple days. Thanks for everyone's help.....
 

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Good news Derek!
 

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Discussion Starter #12
Spoke too soon. Though I'm not sure if this issue has really anything to do with the NSBU. If anything my tinkering with swapping NSBU's and not having them aligned properly most likely only contributed to the issues experienced. I do believe now the NSBU


Yesterday I had several issues:


Start truck after sitting for 8 hours, let the glow plugs heat and turn off, about 15 after this put it into D. This is followed by a pretty harsh engagement and what appeared to be 3rd gear or higher, more on that later. Turned off the truck for 30 seconds. Restart, put it into D engaged in 1st and appeared to be normal. Just after leaving our work complex and getting onto a highway on ramp truck seems to go from 2nd or third straight to 5th. On the highway I could tell the converter wasn't locked up, had around 2100 rpm at 65mph. Even after the truck was up to normal operating temp the converter still wouldn't lockup. About one minute of continuous 65mph driving on the highway the IP cluster goes completely dark and stays in this condition for about 10 seconds, then suddenly it powers back up.


Exiting the highway coming to a stoplight and taking off from a stand still it appeared as if only 4th or 5th was present as the truck seriously labored to get up to decent speed. Coming up to the next stop, shut off the truck and restart. Put truck into D with indictor light lit on D, press the gas and it had no gear engagement, truck wouldn't move. It took two more cycles of shutoff, restart, put into D before the truck would engage in gear (SES light now on). Amazing on my last cycle it engaged first and the remainder of the ride home was eventless.


I got home I took out the O/hp Predator program that I had correcting for the 265/245 tire size difference and restored the stock program.


This mornings drive to work was prefect with no issues. Took the truck out at lunch, no issues. I'll proceed to drive it this way for the next 48 hours or so. I don't think I've gone longer than 2 days without some incident from the truck.


First question is anyone have any recommendations at this point? I've tried to be as detailed as possible.
 

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Those are so much like NSBU symptoms. Wonder if there's problem with the terminal connection or harness.

Also, there once was an issue where the harness rubbed as it went around some bracket up around the engine. I forgot the exact details but I think it was around where the red jump start box is. Check for chafing there.
 

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I remember the wire chafing issue that dmaxalliTech bought up. I believe it was one of the wire bundles near the ECM. Don't have time to search for it now. May have been on the other site.
 

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Discussion Starter #15
This morning with the door of the truck open and me standing in the door way I started the truck. Upon starting I heard some clatter or erratic ticking. Almost like a solenoid/relay engaging on and off erratically. Four or five minutes later I got in the truck and took off without incident. Later today started it, put it in D got a firm clunk and got what appeared to be something other than first. Shut truck off and back on. Everything appeared to be fine, though that lasted till I pulled out of our complex. The truck while accelerating was shifting up one gear then back down, backup and down, then finally settling on 2nd gear (3+k rpm) until I came to a stop, then it selected what appeared to be fourth gear only.


Drove the truck into the dealer and am awaiting diagnosis.Edited by: Derek M
 

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Does this sound similar to a possible problem w/this switch???
i was parked in a field, there were some small ruts(3-6" deep) from last fall.went to leave, start up,(had only sat for bout 75-90 mins)I could swear i put it in R, start to move and truck lurches few times, as i looked at the shifter it was just dropping into neutral.... I was like WTF???At first i thought it was just truck bouncing over the ruts.i was only going idle speed.. Is it possible that i somehow got inbetween R & N??? After i got on smooth level ground i tried to do it, but could see no way how, truck seems to drive and shift perferectly fine the 7mile ride home. Later i drove 100 mile roundtrip, and didnt ahve any issues???
 

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Discussion Starter #18
I believe it's fixed. Driven fine now for over 72 hours, not a glitch.


Dealer said it was a bad ignition switch.


Here's the blurb from the invoice......


VOLTAGE SYSTEM READS LOW Check and Report


N2328 run diagnosis, found ignition 0 circuit low in IAC, open circuit in ignition switch. Replace the ignition switch assembly.


26098763 Switch $104.49


Looks like I got hit with around 2 hours labor to R&R. For around $225 can't complain, heck nearly half of that buying NSBU's from the Allison dealer.


Now the 8 million dollar question is what exactly did they replace? My wife picked up the truck, so I didn't get to ask the specifics....
 

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Derek did you ever check the harness?

polarbear.... anytime strange things happen with the gear display and tranny at the same time it's a good possibility there is a problem with the NSBU switch on the side of the tranny.
 

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I would look carefully at the harness from the TCM, routes down by the p/s hose return clamp. 02 trucks should have been corrected, but I would look there. Take it right out and look carefully if it acts up again... Ign switch dont sound right to me.... but..?
 
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