2005 MY OBD System Operation Summary for Gasoline Engines

A:(-1(%$> );;!0#The ZF 6HP26 is a 6-speed, step ratio transmission that is controlled by a standalone Transmission ControlModule (TCM), The TCM communicates to the Engine Control Module (ECM), ABS Module, Instrument Clusterand Transfer Case Control Module using the high speed CAN communication link. The TCM incorporates astandalone OBD-II system. The TCM independently processes and stores fault codes, freeze frame, supportsindustry-standard PIDs as well as J1979 Mode 09 CALID and CVN. The TCM does not directly illuminate the MIL,but requests the ECM to do so. The TCM is located inside the transmission assembly. It is not serviceable with theexception of reprogramming.;Transmission Range SensorThe non-contacting, Hall effect Transmission Range (TR) sensor provides four digital inputs to the TCM. Each 4-bitpattern corresponds to the driver-selected gear position (Park, Rev, Neutral, D6, D4, 3, 2, 1). The 4-bit pattern ischecked for invalid combinations (P0705).Speed SensorsThe Turbine Shaft Speed (TSS) sensor and Output Shaft Speed (OSS) sensor are Hall effect sensors.The Turbine Shaft Speed sensor is monitored for circuit faults and rationality (P0715, P0717). If turbine shaft speedexceeds a maximum calibrated speed (7,700 rpm), a fault is stored (P0716). If engine speed and output shaftspeed are high and a gear is engaged, it can be inferred that the vehicle is moving. If there is insufficient outputfrom the TSS sensor a fault is stored (P0716).The Output Shaft Speed sensor is monitored for circuit faults and rationality (P0720, P0722). If output shaft speedexceeds a maximum calibrated speed (7,450 rpm), a fault is stored (P0721). If output shaft speed does notcorrelate with turbine shaft speed and wheel speed while a gear is engaged and the vehicle is moving, a fault isstored (P0721). If the output shaft speed decreases at an erratic/unreasonable rate, a fault is stored (P0723).Transmission Fluid TemperatureThe Transmission Fluid Temperature Sensor is checked for open circuit, short circuit to ground, short circuit topower, and short circuit of the sensor (P0711, P0712, P0713, P0714). The transmission fluid temperature ischecked for an erratic signal (P0714) and is also compared with the internal TCM temperature sensor as arationality check (P0711).;Shift SolenoidsThe Shift Solenoid output circuits are duty-cycled outputs that are checked electrically for open circuit, short circuitto ground and short circuit to power by monitoring the status of a feedback circuit from the output driver (SSA -P0973, P0974; SSB - P0976, P0977; SSC - P0979, P0980; SSD - P0982, P0983; SSE - P0770, P0985, P0986).In addition, during steady states, the current flow through the Variable Force Shift Solenoids is calculated based ona current feedback signal and compared with a target current value (SSA low current - P0972; SSB high current -P0975; SSC low current - P0978; SSD high current - P0981).The shift solenoids are functionally monitored through gear ratio and shift monitoring. The actual gear ratio versusthe expected gear ratio is monitored. If there is a mismatch, a fault is stored (1 st gear - P0731; 2 nd gear - P0732; 3 rdgear - P0733; 4 th gear - P0734; 5 th gear - P0735; 6 th gear - P0729; reverse gear - P0736). Shifts are alsomonitored. If the ratio characteristics do not change properly during a shift (rpm does not go down during an up-FORD MOTOR COMPANY REVISION DATE: APRIL 28, 2004 PAGE 123 OF 131