Help!! I have an 03 DTS, wonderful automobile, just turned 50K....and then BAM!!! SERVICE ENGINE SOON. The converstion with the OB Computer yielded PO717. I Understand that this VSS is IN the transmission? The part itself is only 69.99 however I have read tale that the installation can cost upwards of 1K? Does anyone know where exactly in the tranny this part lies? Is it accessable through the trans pan behind the valve body or what? 1200 will rebuild the tranny. It seems this rumored price indicates a transmission dissasembly and may be just a tad out of my scope. Whats the nomeclature for this transmission. Any help appreciated. Matter of fact, if I clear the PCM I get a few minutes of smooth shifts then back to banging gears and over-reving and the dreaded Service light.

 

To clarify the nomenclature, p0717 refers to the ISS not the VSS. (Input Speed Sensor vs Vehicle Speed Sensor).

To access the ISS the drivers side of the transmission must be disassembled. The sensors location is bolted to the case of the unit behind the upper control channel plate, between the drive sprocket and driven sprocket. The sensor faces the drive sprocket as it uses the teeth on that sprocket to generate the required speed signal.

I would pass on a $1200 rebuild. That is very cheap for a 4t80 unit. I would suspect inferior parts or additional costs to come up once the unit is apart. Not to mention it is a very labor intensive rebuild in comparison to most.
A GM torque converter is over $600 by itself. This is the most common problem part on your unit. I would only replace with a GM converter unless a FULL GUARANTEE is provided.

Sorry to hear of the costly repair, it is not a very common problem on your specific model.

 

Thank you so very much.