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4l80 ?

Reverse lights is the nsbu mounted on the shift shaft. Input speed sensor is the 2 wire sensor mounted up on the drivers side just behind the bellhousing area.
 
That switch that slides over the shift shaft must be aligned correctly internally before you slide it on. Per the GM shop manual, there is a special GM jig tool that aligns the bushing with the contact and holds it in place as you slide the switch onto the shaft. After it's on and bolted in place you remove the jig. This could very well be the reason you don't have reverse lights. Also check to see if your Park/Neutral safety interlock is dead on (do you have to slightly jiggle the shifter lever on the column to get it to start in either/or/both Park and Neutral) in alignment as that is also a function of that switch. If you have problems with the Park/Neutral, then that alignment issue is almost certainly also your no Reverse lights culprit, too.
 
There's a ground on rear drivers side frame at the back past rear tire. It's a white wire with a ring terminal. Try cleaning that and see if it works.
 
Husker6.5 said:
That switch that slides over the shift shaft must be aligned correctly internally before you slide it on. Per the GM shop manual, there is a special GM jig tool that aligns the bushing with the contact and holds it in place as you slide the switch onto the shaft. After it's on and bolted in place you remove the jig. This could very well be the reason you don't have reverse lights. Also check to see if your Park/Neutral safety interlock is dead on (do you have to slightly jiggle the shifter lever on the column to get it to start in either/or/both Park and Neutral) in alignment as that is also a function of that switch. If you have problems with the Park/Neutral, then that alignment issue is almost certainly also your no Reverse lights culprit, too.
Click to expand...

You're talking abou the black box with the slide lock that pushes over the ball? I haven't gotten to the reverse issue yet. The shifter works fine and I haven't had a chance to jiggle the shifter yet. I am done with the front end work,and only the drivers side ball joint was bad, but I changed both to appease the inspector.
 
I'm talking about the quadrant-shaped black box with the two electrical connectors on the right, attached to a metal bracket with three slotted bolt holes for adjustment, that slides over the shift selector shaft on the driver's side of the transmission. That switch must be correctly internally aligned before sliding it onto the shift selector shaft and bolted in place.
 

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Husker6.5 said:
I'm talking about the quadrant-shaped black box with the two electrical connectors on the right, attached to a metal bracket with three slotted bolt holes for adjustment, that slides over the shift selector shaft on the driver's side of the transmission. That switch must be correctly internally aligned before sliding it onto the shift selector shaft and bolted in place.
Click to expand...
The adjustment has nothing to do with before it's put on. The alignment tool just locks the switch dead center in nuetral for installation. Put the trans in nuetral, slide it on, and bolt it down, done deal. You can do it without the alignment piece as I've done several. The problem with doing these that most make is they don't deburr the shift shaft BEFORE they begin the job. Once you remove the shift arm, take a small flat file to the end and remove any sharp edges. Otherwise those sharp 3dges will cut and gouge the plastic inner portion of the bsbu making it fit loosely onto the shift shaft. It must fit tightly for it to follow the shift shafts movement.
 
I used the existing shift selector that was on the transmission I installed. It shifts fine and the only issue I have is the input shaft vas code. Does the reverse lights go through this selector as well as the reverse switch on the column? I haven't had a chance to power probe the circuit yet, but the reverse switch moves all over the place as the black rod is pushed into the switch. Tomorrow I will start testing for power in the circuit. Thanks again for everyone's input. I am so need a second set of eyes to watch the reverse lights as I wiggle the shift lever while in reverse.
 
Also, Great White(BJ) posted a TSBabout the shift selector from GM saying that the dielectric grease caused an inop issue which could a no reverse light issue, but this is from a company that changed IP's because of pmd. I'm not buying or replacing anything till I test electric current. I spent my spare time cleaning the ground near the tail lights, which were questionable but still no go. All other bulbs work and I doubt both circuit boards are bad back there.
 
Usually when the circuit boards went bad it was brake lights circuit in my experience, not reverse. But if you back up a lot, i guess... Haha.
Probe the connector going into the board if you suspect it, otherwise i think bsbu is still your target.
 
The nsbu on the trans is the only reverse switch on a 95+ truck. There is no column mounted switch after 94.
 
That's the shaft from the shifter and there is the offset black rod that moves the that black switch.
 
Shift interlock. Thats what locks the shifter from moving until you step on the brakes. It's powered on via the brake switch, and grounded via the nsbu switch on the trans.
 
Thanks again, I ordered a new nsbu switch and thinking about new plugs as I think they maybe the issue. I am going to unplug and replug existing electronics , as they went in as hard as they came out. I really need to use this truck for a job.
 
Ok, looking at my alldata, in the 7 wire plug there should be a pink in spot C, and a light green in spot F. The pink wire should be hot with the key on from the turn signal backup lamp fuse, and the light green wire runs back to the backup lamps. Check for power at the pink wire in spot C with the key in the run position, if you do, install a small jumper wire to the light green wire in spot F and the lights should come on.62535521.gif
 
Thank you, that helps a lot as I've no access to what wire does what, mostly cause I never had the need in the dozen years I've had this truck. All my other steel is precomputer and have had electrical issues, but I know what every wire goes to. Thanks again, and how are you feeling these days?
 
Sore, I'll leave it at that. Been diagnosed with fibromyalgia, chronic pain syndrome, prior orthopeadic conditions, and now it looks like I've got a problem in my upper spinal cord as I keep randomnly losing the use of my arms(never both, it will be one, then the next day it will be fine and the other will be unuseable).
 
I'm sorry, but can relate. I have the same diagnosis. Seven back surgeries and the rest I don't want to get into. I really appreciate your help because it save wear and tear on me. Thanks again.
 
I actually wished they thought a surgery would help me. They can't pin point anything with me other than extreme pain that's constantly moving around.
 
That's the story I got with my neck. Different pain and symptoms daily and deemed to risky to try anything. The only thing thy will fix is carpal tunnel from all the EMG testing. Meanwhile I have pain everywhere on any given day. Sorry to hear they won't or can't do anything.
I poked around my wiring and at the fuse box and it's dead in reverse. With the turn signal on it clicks under the hood,and with nothing on the circuit the test light makes a clicking noise under the dash. At the plug by the nsbu key on in reverse, the pink wire has power, jumped to the light green wire brings nothing the the bu lights. That being said, the wire colors were in different spots in the plug. Any ideas, thanks again.
 
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