o/d problem
 

Just bought a 1990 pickup V6 auto 4wd. Speedo cable is broken off at the end that connects to the trans, the truck will not stay in o/d and continually shifts in and out. It is flashing a Code 42 which I understand is VSS no. 2. Here's the issue, will the new speedo cable solve this or is the #2 vss bad as well? I've searched and read all that I can find about this, the online manual only covers the 1993 model with the electronic speedo. Thanks

Is yours mechanical or electric speedometer? I would start with then, since you said it's broken then go from there

According to the manual, code 42 is VSS1, not VSS2. http://personal.utulsa.edu/~nathan-b...31diagnosi.pdf

VSS1 comes from the Combination Meter (I believe 1990 pre-dates the electronic on-transfer-case VSS1). Here's how that works: http://www.autoshop101.com/forms/h16.pdf

Having no VSS1 signal will make it very hard for the transmission; I don't know if that will specifically prevent o/d, but it is definitely "not good." So fix it. Of course, a "broken off" cable suggests quite a bit of trauma; you might want to confirm that it is only the cable, and not also the parts internal to the transmission.

It is a mechanical speedo.

Thanks for the link scope103, looks like I need to address the combination meter/speedo cable problem. I wasn't sure if the speedo cable sent any signal to the ECU, I guess it does. I was mixed up with the codes as well. I'll hit the boneyard for a cable tomorrow. Thanks for the help, I'll keep you guys posted.

I replaced the speedo cable with one from a manual trans today. The speedo works but seems to be reading high. The o/d issue is still the same. Won't stay in o/d for more than 2-3 seconds and downshifts every time. I'm not sure what to check next,anyone have any guesses?