Brake Transmission Shift Interlock Control

WARNING: This page is about a different car, the 2004 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.

On models with an automatic transmission, the EMIC Brake Transmission Shift Interlock (BTSI) control is only active when the gearshift selector lever on the steering column is in the Park position. The BTSI locks the gear selector lever in the Park position when the BTSI solenoid control coil is energized, and unlocks the lever when the control coil is de-energized. When the EMIC receives battery current on the fused ignition switch output (run-start) circuit (ignition switch is in the On or Start positions), and either the hard wired Transmission Range Sensor (TRS) input to the EMIC or the electronic gear selector indicator messages received from the Transmission Control Module (TCM) indicate that the gear selector lever is in the Park position, the EMIC provides battery current through a high-side driver to the BTSI solenoid control coil.

The BTSI solenoid control coil is connected in series between the output of the instrument cluster and ground through the normally closed contacts of the brake lamp switch. The brake lamp switch provides the BTSI solenoid with a path to ground only when these-normally closed switch contacts are closed (brake pedal is released), and de-energizes the solenoid to unlock the gear selector lever from the Park position only when the switch contacts are opened (brake pedal is depressed). However, if the EMIC senses a short or open in the TRS input or if the EMIC receives no electronic gear selector position messages from the TCM, the EMIC will automatically de-energize the BTSI solenoid to unlock the gear selector lever from the Park position.

The hard wired inputs to and outputs from the EMIC that control the BTSI solenoid may be diagnosed using conventional diagnostic methods. However, proper testing of the EMIC, the TCM, the PCI data bus, or the electronic gear selector indicator (PRNDL) messages sent by the TCM to the EMIC requires the use of a DRBIII(R) scan tool. Refer to ELECTRONIC CONTROL MODULES .