Key Fob
You want a scan tool equipped with diagnosis function for ALL electronic control modules, in return!
Just for my info, I went to two different repair shops. One is a independent shop. They do a lot of repairs. Told me to scan and find problem is $178.00 . The other is a GMC, Cadillac, Buick dealer. Cost to scan and find problem $184.00. Of course I would have to tow to each place. Same distance, just different direction. I did this to get a idea of what I may have to do, if I cannot fix it.
Here's more info on the p0651 (5-Volt Reference 2 Circuit): DTC P0641 or P0651


