I bought a 2009 H3 Alpha about a year ago and have had some serious issue with it ever since. Approximately 18 months before I purchased the H3, the previous owner had a complete transmission rebuild. When I started driving it, the H3 would sporadically get caught in 2nd gear. I'd have to pull over, shift the car into park and then back into drive to correct the issue. I took the car back to the shop and he gave me a significant discount for a second transmission rebuild. A few months after the 2nd transmission rebuild, the H3's transmission was still getting caught in 2nd gear (though less frequently). I took the car back to the transmission shop but he could not pull any codes or see any issues with the transmission. I also took the car to the GM Dealership; they could not find any issues either. About 3 months later I noticed the battery cable connectors were loose and I replaced them. Surprisingly this actually improved the performance of the transmission and I had zero issues for 2 months.


Now, on occasion, the speedometer continues to read 0 mph when I start driving from a complete stop and the transmission does not shift from first gear.


I'm not a mechanic but I have been doing some research (largely on this forum). The issue could be a faulty Vehicle Speed Sensor (VSS), as this would explain the speedometer issue but I'm not sure that this would cause the transmission to not shift. Do any gurus have any other suggestions? I'd really appreciate some help....I've been sinking a lot of money in hopes of turning this lemon into a functioning vehicle.

 

Sounds like a VSS issue.
I do believe the VSS would effect shifting also since (if I remember correctly) the vehicle speed is just one of the factors the PCM uses to determine when to shift.

 

Hopefully you replaced the Battery Terminal Connectors with a quality aftermarket set like stinger?

Yes, the Speed Sensor most definitely 100% will stop the trans from shifting because it does not know what your speed is. Example, if you take a vehicle with perfectly functioning trans and disconnect the VSS, it will not shift out of 1st, raging RPMs or not.

Faulty speed sensor??? not likely, but any electrical sensor has a potential to fail. Check the wiring to it and connection, make sure it is fully seated and tightened.

 

How difficult of a job is it to replace VSS myself? It seems simple on other cars watching on youtube. I cannot find a 2009 H3 Alpha specific video on how to replace. Or a step by step guide. Thank you!

 

 

I replaced it with a $10 set from autozone... how bad of a move?

 

https://www.autozone.com/batteries-s...985_23849_9028

These in fact...