Problems with 95 GMC 1500

sdtom · August 29, 2016

I Have a 95 GMC 1500 pickup with a 5.7 liter motor. The SES sometimes and the Trans stays in 3rd and does not shift then the light goes off and the truck runs great. We had the trans rebuilt about 5000 mile ago. I tried to get the codes and the first time it just came up with the code 12. After that it run great for about 20 miles I parked it and when I started it again later the SES light came on then I got the codes 32 EGR 34 MAP 42 and 45 both are oxygen sensor codes. Before trying it the first time it had the light on most of the time.

Does anyone had a idea of what is going on?

Thank you in advance

Tom

ifixedit · August 29, 2016

Don't know if O2 sensor codes would be causing the trans to not shift properly, but who knows? I'd first maybe be checking for faulty wires and or connections at the O2 sensors. I've heard of wires laying and burning on the exhaust, ect. I'm assuming if the trans came out of the truck for a rebuild that perhaps the O2 sensors needed to be disconnected to possibly get wires out of the way? So, again maybe it's just a faulty / bad wire / connection issue to the sensors. I've found over the years the various plugs here and there can be pretty fussy to being disconnected and re-connected. GM doesn't exactly use the best gauge of wire either.