P0729 GMC Automatic Transmission 6th Gear Incorrect Ratio
Possible causes
– Low transmission fluid level
– Shift solenoid mechanical fault
– Hydraulic circuit fault
– Transmission failure
– Shift solenoid mechanical fault
– Hydraulic circuit fault
– Transmission failure
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
– Transmission will not shift into 6th gear
– Transmission will not shift into 6th gear
P0729 GMC Description
This malfunction is detected when the A/T does not shift into 6GR position as instructed by TCM. This is not only caused by electrical malfunction (circuits open or shorted) but by mechanical malfunction such as control valve sticking, improper solenoid valve operation, etc.
GMC Vehicle:GMC Acadia,GMC Canyon,GMC Envoy,GMC Savana 1500,GMC Savana 2500,GMC Savana 3500,GMC Sierra 1500,GMC Sierra 2500 HD,GMC Sierra 3500 HD,GMC Terrain,GMC Yukon,GMC Yukon XL 1500,GMC Yukon XL 2500,