GM Repair Problems? Ask GM Repair Expert Now.
If the speedometer is bouncing then most likely you have a bad connection at the vss " vehicle speed sensor " or the sped sensor itself is going bad. Do you have any transmission fluid leaking out around the plug for the vss?
Yes the vss can cause the transmission to change gears if the speed signal is lost. The vss tells the pcm how fast you are going and then tells the shift solenoids what to do and when to change gears. No vss signal and the pcm does not know what gear to tell the trans to be in.
It would have been the first place I would have gone to. To tell you the truth, the vss is not so easy to check. It is a magnet that picks up in the toner ring on the out put shaft. The teeth on the toner ring will cause a pulse when the teeth pass the tip of the sensor. The pcm picks up on the speed of the pulse to know how fast you are going. All magnets loose there strength over time and with heat. The vss cost about $30.00 and is very easy to replace, you have to jack up the driver side " more to the rear so you do not loose fluid" and then unplug the sensor. There is one bolt holding it in you have to remove. Then you have to use a screw driver to pop it out. Lube the new seal and pop the new one in bolt it down and plug it up. It should only take about 10 minutes to do the job.
You can do the job yourself, it is really not hard to do.
Do you know what transmission you have in your truck? Is it a 4l60 ora 4l80 E?
Can you send me a pic of the transmission pan?
That is the 4l80 e transmission. Let me do a little more digging with the codes you have.
The first thing I would check would be to see if there is any trans fluid in the main plug on the passenger side of the transmission. It will be a round plug with about 15 wires in it. Unplug it and see if there is any fluid on the plug s bottom.
He may have reset it. If the engine is stalling there may be a problem with a vacuum leak, or the idle control motor. Do you have the van with you and are you able to do some testing with me to see what is going on?
I work on here till about 6 am my time and then have to get some sleep, I get up around 12 noon eastern time. Can we work on it some where around there< or do I need to stay up so we can work on this in the morning? I do not mind just need to know how to plain my night tonight.
We can work on this in the am if you would like, there is no reason for you to go now.
That is good. Chat with you tomorrow.