Transmission Datalogger

Selecting 'Transmission from the vehicle area menu will present the technician with the following transmission diagnostic tools menu:

The Datalogger function is fully described in the worked example at the rear of this PDU Users Guide.

Transmission Datalogger

The PDU datalogger function may be used to monitor the following transmission controller signals

DTCS Number of DTCs Logged

The Diagnostics status manager (DSM) receives and processes fault information and decides when a DTC should be logged and the MIL turned on (if enabled). The actual total stored is indicated by the parameter DTCS.

FBRAKE Brake Switch

The footbrake switch signal is input to the TCM. The input is normally at ground potential and goes open circuit when the brakes are applied. If the torque converter clutch is applied it will disengage when this signal is detected.

FMA Actual Force Motor Current

The force motor regulates the transmission fluid pressure. It is a variable force solenoid whose coil current is determined by the TCM. Range 0 - 1.245 amps. A driver circuit limits excessive current flow and performs a ratiometric comparison of Desired (commanded) Force Motor Current and Actual Force Motor current. The parameter monitors the Actual Force Motor current 1 Bit = 1/204.8amps.

HOT Hot Mode

The signal from the transmission temperature sensor is used to control TCC and line pressure. It is also used in many diagnostic signals and is a critical component for OBD II. Above 120°C the TCC is on in 2nd, 3rd and 4th gears. This reduces transmission temperature by decreasing the heat generated by the torque converter. It also provides maximum cooling by routing transmission fluid directly to the transmission cooler in the radiator. When the Hot Mode is ON the bit is set to 1.

IGN+ Ignition Feed Positive

The TCM receives ignition voltage through TCM pin 53.

MD Desired Force Motor Current

The force motor regulates the transmission fluid pressure. It is a variable force solenoid whose coil current is determined by the TCM. Range 0 - 1.245 amps. A driver circuit limits excessive current flow and performs a ratiometric comparison of Desired (commanded) Force Motor Current. The parameter monitors the Desired Force Motor current 1 Bit = 1/204.8amps.

RATIO Actual Gear Ratio

The diagnostic detects malfunction in the transmission output components by monitoring the actual gear ratio. The actual gear ratio is calculated using input (Ni) and output speed (No): Ratio = Ni/No. This is compared with the standard gear ratio for each gear. Malfunction can be defined as: actual gear ratio is not equal to any of the standard gear ratios.

RPM Engine Speed

The engine speed signal is input from the instrument pack. The signal originates at the crankshaft sensor. The crankshaft sensor signal is modified by the PCM and the instrument pack before being input to the TCM.

SSA Shift Solenoid A

Shift solenoid A is attached to the valve body and its outlet is open to exhaust when it is switched off. A OFF - outlet open - 2nd and 3rd gears selected. The solenoid is energised by the TCM providing an internal ground to close the outlet. A ON - outlet closed - 1st and 4th gears selected.

SSB Shift Solenoid B

Shift solenoid B is attached to the valve body and its outlet is open to exhaust when it is switched off. B OFF - outlet open - 1st and 2nd gears selected. The solenoid is energised by the TCM providing an internal ground to close the outlet. B ON - outlet closed - 3rd and 4th gears selected.