2005 MY OBD System Operation Summary for Gasoline Engines

Transmission Fluid TemperatureThe Transmission Fluid Temperature Sensor is checked for open circuit, short circuit to ground, and short circuit topower (P0710). The transmission fluid temperature is checked for an erratic signal and is also checked for rationalvalues versus inferred TFT (P0711, P0714). Pressure control solenoids have a known resistance versustemperature characteristic. TFT is inferred by measuring the voltage and current of the pressure control solenoidsto get resistance, then temperature.Note that TFT failures are do not illuminate the MIL because TFT failures result in substituted the inferred value ofTFT. Normal transmission control continues, and all emission-related diagnostic tests continue to run.If the transmission fluid temperature exceeds 212 deg F, a P0218 fault will be stored.;Pressure Control SolenoidsThe CFT30 uses 5 pressure control solenoids. Each solenoid is checked electrically for opens, shorts to ground,and shorts to power by monitoring the status of a feedback circuit from the output driver. They are the MainPressure Control Solenoid (P0960, P0962, P0963), Primary Pulley Pressure Control Solenoid (P0964, P0966,P0967), Secondary Pulley Pressure Control Solenoid (P0968, P0970, P0971), Forward/Reverse Clutch PressureControl Solenoid (P0900, P0902, P0903), and the Torque Converter Clutch Solenoid (P0740, P0742, P0743).The forward/reverse clutch, torque converter clutch (TCC), and ratio control solenoids are functionally monitored. Ifthe TCC is released and the speed ratio of the converter is out of physical range, a fault P0741 will be stored. If theTCC is fully applied, and the converter clutch is slipping, a P0741 fault will be stored.The forward/reverse clutch is checked tested for slippage by comparing the turbine speed and primary pulleyspeed. If the difference between TSS and primary pulley speed exceeds a calibrated threshold, a P0811 fault willbe stored. If the clutch is stuck, a P0810 fault will be set.The ratio control check detects if the variator belt is slipping by comparing primary pulley speed (PSS) tosecondary pulley speed (TSS). If the ratio is out of the expected range of 0.28 to 2.7, or is changing at a rategreater than a ratio of 0.5/second, then a P0730 fault will be stored.High Side Actuator Control CircuitThe TCM has a high side actuator supply control circuit that can be used to remove power from all solenoidssimultaneously. The actuator control circuit is tested for open and short circuits to power and ground. (P0657,P0658, P0659).;!%;!)The TCM monitors itself by using various software monitoring functions. If there is an EEPROM fault on power up,a P0613 fault will be stored. If there is a power up or continuous RAM fault, a P0604 fault will be stored. The flashROM is continuously checked using a checksum calculation. If the checksum is incorrect, a P0605 fault will bestored. If there is a watchdog timer failure, a P0702 fault will be stored. If the diagnostic software tries to enter twocontradictory failure mode strategies or if there are contradictory output states commanded versus the expectedoutput states, a P0701 fault is stored.CAN Communications ErrorThe TCM receives information from the ECM via the high speed CAN network. If the CAN link or network fails, theTCM no longer has torque or engine speed information available. The TCM will store a U0073 fault code if theCAN Bus is off or a U0001 if no acknowledgement to an outgoing message is received. The TCM will store aU0100 fault code if it stops receiving CAN messages from the ECM. If the engine speed from the ECM isunreasonably high (> 7500 rpm), a P0219 fault will be stored. The TCM will store a P186D fault code if theTransfer Case Control Module is unable to control the four-wheel drive clutch.FORD MOTOR COMPANY REVISION DATE: APRIL 28, 2004 PAGE 121 OF 131