Replacing nsbs

[Diesel_D]

I have a 02 Dmax and for the third time the nsbs has gone bad. I went to my local auto parts and replaced the switch and nothing changed. They gave me a new switch and still nothing. The truck is doing the same thing it did the first two times. I talked to a friend who is a transmission mech and he said they are prob giving me a switch for a 4l80 e trans and not the allison. The switch looks the same as the one i pulled off. Anyone have this same expierience.

[DmaxMaverick]

Maybe start off here with the problem, which is __________ (fill in the blank). Replacing parts that don't fix the problem, especially repeatedly, usually means that isn't the problem.

[Diesel_D]

Truck is acting the same exact way as the first two times i replaced the switch. Ses light on,drive shaft clunks like crazy when shifting into drive and trans is stuck in 3rd. This would be my 3 rd switch in 200k miles. My question was is it possible they are giving me the wrong part? Are you say ing something else could be mimicking a bad nsbs switch? Thanks

[DmaxMaverick]

Doesn't sound, to me, like the NSBU. Sounds like limp mode, caused by something else. The most common indicator of a bad NSBU is missing or flashing gear ranges on the IPC, and/or a failure to engage the tranny, at all. Have you pulled the DTC's? If so, what are they? If the SES is on, there will be codes.

[Diesel_D]

Funny thing is the truck did the exact same thing twice before and i replaced the sensor and it was fixed. Maybe when disconnecting the batteries it reset something and i thought the sensor was the problem. Thanks again for the reply. I'm gonna have to look into this further.

[DmaxMaverick]

Disconnecting the batteries for a period will often reset the PCM. It won't be an issue, until the original condition returns, and you start all over. The conditions you describe aren't normally related to the NSBU. Reading your stored codes will be your best starting point. Anything less is a shot in the dark.