Transmission Component Descriptions

TRANSMISSION COMPONENT DESCRIPTIONS

Shift Assembly
The Shift Lever Selector transmits all selector lever positions, as well as selected shift ranges to the TCM over the CAN Bus. At the same time, the selector lever positions P, R, N, and D are transmitted by a cable to the selector lever shaft in the transmission.

Brake shift inter-lock
To prevent unauthorized shifting out of the park position, the Selector lever is locked in the Park position until the ignition key is turned to the run position and the brake pedal is pressed. This will allow the driver to shift out of the park position.

Reverse Lamp Output
The Reverse Light Switch is integrated into the shifter module and controls the reverse lights.

Reverse Inhibitor
The Shift Lever Assembly constantly monitors ABS wheel speed to prevents an inadvertent selection of reverse at speeds above approximately 6.4 Km/h (4MPH). The Reverse inhibitor is part of the Shift Lever Assembly and is controlled by the Shift Lever Assembly module.

Trans Temp Sensor - P/N Switch Circuit
The TCM will detect the selector lever in park and neutral positions. The TCM does this by monitoring the Transmission temperature sensor signal along with the shifter position signals. The P/N switch contact is operated by a cam located in the transmission which, opens a reed contact switch that is wired in series with the transmission temperature sensor. When the P/N contact switch is opened in park and neutral, the TCM senses a high transmission temperature. Confirming the P/N switch status. Note: In park or neutral, the TCM uses engine temperature (to avoid setting a DTC). The TCM sends a hard wired signal to the ECM that will allow the ECM controlled start circuit to engage in P or N only. The TCM also sends a P/N bus message to the ECM to confirm the P/N switch status.

The Normal Transmission Temperature Sensor resistance is between 500 and 2500 Ohms. The normal voltage limits for the transmission temperature sensor, are between 0.5 and 3.0 volts.

Input Speed Sensors
The NAG1 transmission has two input speed sensors N2 and N3, both speed sensors are located on the valve body and report DTCs for the input speed sensors errors. The speed sensors are Hall Effect speed sensors that are used by the TCM to calculate the transmissions input speed. Since the input speed could not be measured directly, two of the drive elements are measured. Two input speed sensors were required because both drive elements are not active in all gears. The input sensors N2 and N3 will report the same input speed in gears 2nd, 3rd or 4th. If the N2 and N3 input speed signals are not the same in these gears then there is an issue with the transmission and the DTC Input Sensors Mismatch will be set.

The N3 input speed is not reported in 1st and 5th gears. The N2 sensor is not reported in Reverse. The Input Speed Sensor Overspeed is a rationality check that is intended to indicate a major transmission failure and will cause a loss of drive (place the transmission in Neutral)

Output Speed Sensor (ABS signal)
The NAG1 transmission does not have an output shaft speed sensor. The TCM uses the ABS (Antilock Brake System) Wheel Speed sensor information, it receives over the CAN bus, to calculate the transmissions output shaft speed. The TCM monitors the ABS system for functionality and reports ABS speed sensor and communication DTCs, which will affect proper transmission operation.