Hey all, I'm obviously new to the forum, but I'm not new to Blazers. Any how, I picked up a 2000 Blazer with 98k on it for $1400, and of course has a few issues. The biggest one is the transmission not shifting and it throws a P0502 code which states "vehicle speed sensor A low circuit". Swapped the sensor on the T-case. Unfortunately the problem still persists. I got under it again to make sure the wiring was alright, and it appears as though there is a 2nd VSS on top of the transfer case. At least I think that is what it is.... Do the 4wd models have 2 sensors? I've tried to pull it out, but it is in such an odd position I gave up for the time being lol.

Some other things that might help with the diagnosis, the ABS light is on, speedo and odo don't work. And it seems to have some weird electrical gremlin... It acts like it is starved for electricity even when the battery is fully charged, and even has a hard time staying running if the battery gets to low. I haven't put the voltmeter on it yet, but probably will by this afternoon. Let me know what you all think, thanks in advance!

 

Well, I swapped the 2nd sensor, so apparently there are 2 speed sensors on the T-case. The problem still persists ABS light on, ODO and Speedo don't function. Battery terminals read 14.6 volts while the vehicle is running. It is also throwing a second code P500 "Vehicle speed sensor A".

 

Finally found what is the VSS by happen stance when fishing around for any severed wires. I guess there are 3 sensors on the T-case that are identical to the VSS but perform different functions. The first one is located on the passenger side of the t-case and is easily accessible. The 2nd one is a pia and is located on top of the t-case on the driver side. Then the VSS itself is located just behind the 2nd one on the driver side (just follow the wiring). Turns out the thing was just disconnected. Plugged it back in and all is well.