Speedo stops working then trans shifts funny

[SWEETRIDE98]

ok so I have a 97 firebird 3.8 that has 130k just put a tranny in i got from the junkyard with 72k, i drove it for ~200 miles and shifted nice and ran great, now on monday when i started getting really hot out the speedometer would start to flake out the the transmission would start shifting funny then act like it was going into neutral.

So my first thought was Output shaft sensor was going bad so i had a spare sitting around so I swapped it, ugg still doing it. I did some research on the 4l60 and everything points to the output shaft sensor or the wiring to it.

I havent had a chance to look at it again since I swapped the sensor but I was wondering if any one else has had this issue or had any ideas where to look.

[1BADAIR]

yeah. without the oSS it wont shift. without the signal it thinks the car is stopped and goes to first

[SWEETRIDE98]

Thats what i thught but its not the sensor so now i gotta figure out were the signal loss is. ugggg

[Kwazrollinz28]

my moms s/c riv did this and so did my dads 95 silverado.

It can be a speed sensor, Wiring, Or the computer, or if your car has it theres a small box around the computer that controls the speedometer.


You should be able to manually shift on some cars and ONLY get 1st and 2nd gear to work or ONLY 1st gear and then the rest just rev.

[SWEETRIDE98]

my moms s/c riv did this and so did my dads 95 silverado.

It can be a speed sensor, Wiring, Or the computer, or if your car has it theres a small box around the computer that controls the speedometer.


You should be able to manually shift on some cars and ONLY get 1st and 2nd gear to work or ONLY 1st gear and then the rest just rev.

Yeah you can manually shift 1 and 2, i know its not the sensor i alreadly replaced that with a known good one, its gotta be in the wiring or the PCM..... just hoping some one had the same problem and could point me right to the problem, its been too hot the last couple days so tonight is supposed to be cooler im gonna check the wiring see if i get high resistance or something noticable in the connector.

Thanks

[1BADAIR]

remove the sensor and stick your finger in the hole. see if the wheel is loose/broken

[SWEETRIDE98]

Think i found the problem jacked the car up tonight and tugged on the wires going into the plug for the VSS and the purple wire insulation streached like 2" so im pretty sure the wire is broken gonna goto the junk yard tomorrow and cut a plug off another 4l60e harness then solder it on in place of the bad one.

[SWEETRIDE98]

That was the problem the purple wire going into the connector was the issue, I went to the junk yark cut off A vss connector on another GM 4l60e and soldered it in place of the old connector, runs great now!