Transmission Control Switch (TCS & Indicator Lamp (TCIL)

DESCRIPTION
The transmission control switch is a momentary contact switch. When the switch is pressed, a signal is sent to the powertrain control module to allow automatic shifts from first through fourth gears or first through third gears only. The powertrain control module energizes the transmission control indicator lamp (TCIL) when the switch is off. The TCIL indicates overdrive cancel mode activated (lamp ON) and EPC circuit shorted (lamp flashing) or monitored sensor failure.
TRANSMISSION CONTROL SWITCH (TCS)
Symptoms
No overdrive cancel when switch is cycled.
DTC's
P1780, tested during Key On Engine Off (KOEO) Self-Test.
TRANSMISSION CONTROL INDICATOR LAMP (TCIL)
Symptoms
FAILED ON- Overdrive cancel mode always indicated, no flashing for EPC circuit shorted or monitored sensor failure.
FAILED OFF- Overdrive cancel mode never indicated, no flashing for EPC circuit shorted or monitored sensor failure.
DTC's
N/A