99427camaro

iTrader: (1)

just put a new trans in my 02 avalanche and had to cut the wires going to the neutral safety switch then had a hell of a time getting the plugs back out wire it all back up then it would not crank switch the yellow wires and fired up but test driving it would not shift out of 1st when in drive or 3rd but if i put it in second it goes in second also i hook my scanner to it and i can use that to make it shift in all of the gears so it should not be a internal issue, any thought would be great, its a 4l60 and i put a new neutral safety switch in it

also this is a trans right from gm not a no name rebuild, i know its not a car but the truck form turned in not a thing and i know there are some sharp guys on here

Gilbert@Ace Racing

Well, knowing that you cut and spliced the harness at the lever position switch/neutral switch... what does your scanner report in each shift lever position? Yeah, that's pretty basic but let's start there.

g

99427camaro

iTrader: (1)

the saner tells me that the computer is commanding 1 st in all gears but 2nd i checked the wires and when i cut them i staggered them to make sure the all ended up in the right spot, does any one have a wire diagram for the NSS

Gilbert@Ace Racing

I've done the same thing in the past, staggering the cut in a multi wire harness when I needed to do some splicing. That's a good idea. I don't doubt you got it right, but man we really do need to know for sure what the pcm is seeing.

As far as it commanding 1st in each shift lever position, well it's going to do that if there is no speed sensor input. Meaning sitting still and moving the shift lever through the pattern. Most scanners have the capability to show what the shift lever position is. Try looking for that info on your scanner.

The reason I'm focused on that is you stated that it was operating normally prior to the R&R. And of course you cut and spliced the harness. Once we can establish that the wiring is correct we can move on to other tests.

And let me add this... until you can get it to shift properly I would suggest that you place the rear axle on jack stands in order to take any load off of the transmission during testing. If it sees a load and something is not right it may get damaged internally. If you can get the wheels off the ground safely, then place the shifter in O/D watch the scanner for proper lever position switch info and then run it and see if it is commanding an upshift to 2nd and so on.

g

Brian68

In the future, just take the switch off with the 2-13mm head bolts, file off the mushroomed end of the manual shift shaft, and let it hang while dropping and installing the trans. Install is a little tricky but with patience you can get the bolt under the connector back in. Those earlier-style park neutral switches SUCK! You will be needing this.

Gilbert@Ace Racing

That's very good info dude! I save the file for future reference myself.

Thanks for taking the time to post that!

g