Test C: DTCs B1987, B1990 and B1991 - Pedal Forward/Rearward Motor Stalled and Potentiometer Circuit Failure

Pinpoint Test C: DTCs B1987, B1990 and B1991 - Pedal Forward/Rearward Motor Stalled and Potentiometer Circuit Failure
Refer to Vehicle/Diagrams, Adjustable Pedals for schematic and connector information.

Normal Operation
The driver seat module (DSM) uses a potentiometer attached to the pedal motor to identify the current pedal position. The DSM sends a reference voltage to the potentiometer along circuit 446 (OG/WH) (a common feed circuit shared by memory seats), the reference voltage returns to the DSM along circuit 447 (OG/RD) (a common return circuit shared by memory seats) and the DSM receives the pedal position signal from the potentiometer along 1491 (LB/YE).

When one or more of the following DTCs are set, the adjustable pedals will enter a "jog mode". This means that when the adjustable pedal is pressed, the motor will move the pedals for one second regardless of the length of time the button is actually pressed.
^ DTC B1987 Pedal Forward/Rearward Motor Stalled - This DTC is only set during a DSM on-demand self test. During the self-test, the adjustable pedal motor will be commanded to move forward and then rearward. If the motor encounters a hard stop while moving, the DSM will attempt to move the pedals in the same direction again. If the DSM does not see any pedal movement via the potentiometer during this attempt, DTC B1987 will be set.
^ DTC B1990 Pedal Forward/Rearward Potentiometer Feedback Circuit Failure - If during normal operation or an on demand self test, the DSM detects an open or a short to ground on the potentiometer feedback circuit, DTC B1990 will be set.
^ DTC B1991 Pedal Forward/Rearward Potentiometer Feedback Circuit Short to Battery - If during normal operation or an on-demand self test, the DSM detects a short to battery voltage on the potentiometer feedback circuit, DTC B1991 will be set.

This pinpoint test is intended to diagnose the following:
^ Wiring, terminals or connectors
^ Adjustable pedal motor
^ DSM

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