Trans Control Indicator Lamp (TCIL) and Control Switch (TCS)

DESCRIPTION
The transmission control switch (TCS) is a momentary contact switch. When this switch is pressed, a signal is sent to the PCM. The PCM then energizes the transmission control indicator lamp (TCIL) and toggles Solenoid 3 (SS3), applying the forward clutch to provide engine braking and canceling fourth gear operation. TCIL will also flash if the EPC circuit is shorted.

SYMPTOMS
No overdrive cancel when switch is cycled.

DIAGNOSTIC TROUBLE CODES
P1780, tested during Key On Engine Off (KOEO) On-Board Diagnostic only.