Hey guys this is my first post here. I have been looking through the forum and have not been able to find a solution. I have a 95 chevy 6.5 td 178000 miles relocated pmd #9 resistor good pmd and a boost master wastegate controller. Truck runs great on all around no power loss smooth shifts just no shift into overdrive. Any advice would be helpful on where to go next.

 

DTC 15 - Engine Coolant Temperature (ECT) Sensor Circuit High (Low Temp)
DTC 85 - Transmission Gear

Might be 1 for AAMCO?

Check ECT operation or replace senspor in the coolant crossover with AC Delco only and or thermostat.

 

Well I cleared the codes and she ran fine. Light came back on tonight at work I will pull them in the morning after I put in a new temp sensor. Hoping that will solve the problem. It would seem that when it throws the low temp code it puts it into limp mode. Hopefully will be installing my boost guage tomorrow as well. Thanks for the reply.