I'm having a similar problem with my 95 blazer 4wheel.It runs/drives fine up to about 40,then the speedo starts dropping,and the tranny downshifts depending on what the speedo reads.The lower the speedo drops,the lower the tranny downshifts,until my actual speed drops back down below 40 or so,then it runs fine again.I'll hopefully be replacing the VSS later today.

 

I'm having this exact same problem and i changed the vss and it didn't fix it. Any ideas?

 

Are you positive that the new VSS works correctly? I read on another thread,that a member bought a new VSS,and the new one was messed up also.I am not saying that is what is happening with you,but it is possible.
The VSS that I installed was from a 99' s10 out of a junk yard,and I have not had a single problem with my truck since then.

 

I'm pretty sure it's good but my old one was melted a little so I'm thinking I might have a short in the wire the goes to it I need to investigate more.

 

You'll need a 1" socket to remove and replace. Also ck connection before placing back on new one. I also sprayed some electronic connection cleaner. Blazer runs perfect now with 236,000 miles.

 

I also have a similar problem and have accomplished the following. Does anyone have any ideas, I am at a dead end, I don't know what else I can do.
Got my 2000 blazer hung up on a stump just aft of the left front tire. Truck frame was sitting on the stump. Necessary to use jacks and blocking to get it off. In the process exhaust crossover pipe was crushed, approximately 50% closed. I now have a check engine light on which I attribute to an emission issue due to the crushed pipe causing exhaust back pressure. In addition to the check engine light I also have an inop speedometer, and ABS light on and transmission does not shift properly. I have read all the blogs on this issue and have conducted the following. Changed the VSS sensor and did a continuity check of the wiring harness from Sensor connector to the Blue plug pin 29 and 30 at the PCM, and found continuity to be good.


OBD-11 scanner still comes up with P0502 after changing VSS


This all occurred as a result of getting hug up on the stump

 

Dwatson7,
Are you in Sanford Fl? If so I can come over and help.
If you aren't then all I can do is advise you to keep researching your VSS signal.The VSS is the only component on that motor that will cause it to act as I described in the earlier post.So if your truck is acting the exact same way as I described,then either your VSS is bad,or the wiring is bad.
Let me know if that is you in Sanford,and I'll see what I can do.If not,then I would get myself a multimeter and start doing some diagnosing.
John

 

I'm new to this forum and started a new post yesterday; I should have looked around first. That being said, I have changed the VSS (#4 in the diagram as indicated in a previous post) on my 1997 4x4 Blazer and still have an inoperative speedometer. Odometer, trip meter and all other gauges work fine. Any help is greatly appreciated.

 

I have a 2000 Oldsmobile Bravada that won't shift out of 2nd, speedometer doesn't work, and the ABS light is on could it be the same issue with the driver side sensor?? I've replaced the VSS and even solenoid A...I don't know what else to do?

 

There is a VSS that is located on left side transfer case. That is the one I changed out two years ago and have not had any problems since. From what I know about my 97 blazer (Bravada & Jimmy's too) there are a total of three VSS sensors. The two are on the left and right front wheel hubs, the third on driver's side transfer case. Someone may wanna correct me on # number of VSS' though.