P1685 Buick Transmission Control Module Power Up Temperature Sensor Circuit Low Voltage

P1686 Buick Transmission Control Module Power Up Temperature Sensor Circuit High Voltage

Possible causes
– Reprogram TCM and recheck code
– Replace Transmission Control Module (TCM) Sensor/body assembly one piece
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
P1686 Buick Description

The Transmission Control Module (TCM) power up the temperature sensor is located inside of the control solenoid (w/body and TCM) valve assembly and has no serviceable parts. The TCM power up temperature sensor provides the temperature pof the TCM at TCM power up. This temperature readings is used in various shifting and diagnostic routines in the TCM software. This fault is handled inside the TCM and no external circuit are involved.

Buick Vehicle:Buick Regal – ?Buick Riviera – ?Buick LaCrosse – ?David Dunbar Buick – Buick Century – Buick LaCrosse – Buick LeSabre – Buick Lucerne – Buick Park Avenue – Buick Regal – Buick Verano – Buick Enclave – Buick Encore – Buick Rainier – Buick Rendezvous – Buick Terraza – Buick Riviera