THEORY OF OPERATION
The DTC is intended as an informational DTC to aid the technician in determining the root cause of a customer driveability issue. The DTC is also intended to alert the technician to determine if a cooling system malfunction has occurred or if an additional transmission air to oil cooler is needed to support the customers driving behavior.
Friction element distress could result from an insufficient supply voltage to properly control the solenoids. To prevent this possibility, the battery voltage is monitored and the system is placed in logical limp-in if the battery voltage drops below the limit.
The controller is programmed during manufacturing with generic software to facilitate testing. However, generic software does not have the proper calibrations to control a transmission in a vehicle. Generic software checked at power-up. If generic software is found the Malfunction Indicator Lamp (MIL) will light immediately and the MIL will stay on if the fault is cleared until the proper software is installed. Note: Transmission will be placed in limp-in mode.
After the controller is reset (ignition turned to the RUN position), the microprocessor checks the integrity of each Random Access Memory (RAM) location by writing to it and reading back from it. The read value should be same as value written.
After the controller is reset (ignition turned to the RUN position) the microprocessor checks the integrity of the program memory Read Only Memory (ROM). A checksum is calculated by adding all used bytes in the program memory. The sum should be the same as a known constant stored in the program memory.
The internal Watchdog (WD) is a separate hardware circuit that continuously monitors the microprocessor. To insure the proper operation of the Transmission controller the watchdog must receive a signal from the microprocessor within a specific time window (14 msec ± 1 msec) to prevent a system shutdown after a short delay (570 msec). The microprocessor periodically tests the watchdogs ability to provide this shutdown function using a three phase test
1) Send the signal too late > 15 msec
2) Send the signal too early < 13 msec
3) Delay test < 590 msec
If the watchdog input signal arrives too early or too late, the Watchdog Fault line will go low and the watchdog delay will start to time out. The delay will be reset by the correct timing of watchdog signal sent during subsequent operations.
The Delay Test checks the delay time out. The Delay Monitor line is pulled low which forces the delay to start timing out. At the end of the delay time the Transmission Relay will be turned off. The delay test, upon detection of the relay turning off will immediately turn the relay back on before shutdown can occur.
The T41 (C1), T42 (C2), T3 (C3), T1 (C4), T2 (C5) Sense circuits communicate the shift lever position to the Transmission Control System. Each circuit is terminated at the transmission by the Transmission Range Sensor (TRS) switch. Each switch can be open or closed depending on the shift lever position. The Powertrain Control Module (PCM) decodes this information and determines the shift lever position.
Each shift lever position has it own unique combination of closed and open switches, this is called PRNDL code. There are five switches, therefore: there are many possible combinations of open and closed switches (codes). There are 12 valid codes: two for neutral, one for each gear position (5), and five temporary (transition zone) codes. The remainder of the codes should never occur, these are called invalid codes.
The Transmission Temperature Sensor is a variable resistor that changes with temperature or otherwise known as a thermistor. The temperature of the transmission fluid can affect a variety of electronically controlled transmission operations such as shift quality, torque converter lock-up and/or when certain OBDII system self-diagnostic tests are performed. The Powertrain Control Module (PCM) substitutes a calculated transmission temperature value if a fault is detected in the Transmission Temperature Sensor circuit.
The Transmission Temperature Sensor is a variable resistor that changes with temperature or otherwise known as a thermistor. The temperature of the transmission fluid can affect a variety of electronically controlled transmission operations such as shift quality, torque converter lock-up and/or when certain OBDII system self-diagnostic tests are performed. The Powertrain Control Module (PCM) substitutes a calculated transmission temperature value if a fault is detected in the Transmission Temperature Sensor circuit.
The Transmission Temperature Sensor is a variable resistor that changes with temperature or otherwise known as a thermistor. The temperature of the transmission fluid can affect a variety of electronically controlled transmission operations such as shift quality, torque converter lock-up and/or when certain OBDII system self-diagnostic tests are performed. The Powertrain Control Module (PCM) substitutes a calculated transmission temperature value if a fault is detected in the Transmission Temperature Sensor circuit.
The Transmission Temperature Sensor is a variable resistor that changes with temperature or otherwise known as a thermistor. The temperature of the transmission fluid can affect a variety of electronically controlled transmission operations such as shift quality, torque converter lock-up and/or when certain OBDII system self-diagnostic tests are performed. The Powertrain Control Module (PCM) substitutes a calculated transmission temperature value if a fault is detected in the Transmission Temperature Sensor circuit.
The transmission system uses two speed sensors, one to measure input RPM and one to measure output RPM. These inputs are essential for proper transmission operation. Therefore, the integrity of this data is verified through the following checks
1) When in gear, if the gear ratio does not compare to a known gear ratio the corresponding in-gear DTCs P0731-36 and P1736 is set.
2) An excessive change in input or output speeds indicating an intermittent signal which results in DTCs P0716 and/or P0721 setting.
3) If the common speed sensor ground circuit is lost, both sensor inputs will read the signal from the input speed sensor at idle in neutral. Since the input speed sensor reads 60 teeth from the input clutch hub and the output speed sensor reads 30 teeth from the park gear the result is an apparent speed ratio of 1:2 and may cause DTC P1794 to set when at a stop.
The transmission system uses two speed sensors, one to measure input RPM and one to measure output RPM. These inputs are essential for proper transmission operation. Therefore, the integrity of this data is verified through the following checks
1)When in gear, if the gear ratio does not compare to a known gear ratio, the corresponding in-gear DTCs P0731-36, P1736 and P1776 is set.
2)An excessive change in input or output speeds indicating an intermittent signal results in DTCs P0716 and/or P0721 setting.
3)If the common speed sensor ground circuit is lost, both sensor inputs will read the signal from the input speed sensor at idle in neutral. Since the input speed sensor has 60 teeth and the output speed sensor has 30 teeth, this results in a an apparent speed ratio of 1:2 and may cause DTC P1794 to set.
The transmission system uses two speed sensors, one to measure input RPM and one to measure output RPM. These inputs are essential for proper transmission operation. Therefore the integrity of this data is verified through the following checks
Note. Various Gear Ratio Error DTCs will set only if the transmission slips after first achieving the correct ratio. Therefore, a transmission with no drive (or reverse) may not set any Gear Ratio Error DTC because it never achieves a correct gear ratio.
1) Once in a particular gear, if the gear ratio varies from the correct gear ratio, the corresponding in-gear DTCs P0729 and P0731-36 is set.
2) An excessive change in input or output speeds indicating an intermittent signal which results in DTCs P0716 and/or P0721 setting.
3) If the common speed sensor ground circuit is lost, both sensor inputs reads the pulses from the input speed sensor when at a stop in neutral. Since the input speed sensor reads 60 teeth from the input clutch hub and the output speed sensor reads 30 teeth from the park gear, the result is an apparent speed ratio of 1:2 and may cause DTC P1794 to set.
The transmission system uses two speed sensors, one to measure input RPM and one to measure output RPM. These inputs are essential for proper transmission operation. Therefore the integrity of this data is verified through the following checks
Note. Various Gear Ratio Error DTCs will set only if the transmission slips after first achieving the correct ratio. Therefore a transmission with no drive (or reverse) may not set any Gear Ratio Error DTC because it never achieves a correct gear ratio.
1) Once in a particular gear, if the gear ratio varies from the correct gear ratio the corresponding in-gear DTCs P0729 and P0731-36 is set.
2) An excessive change in input or output speeds indicating an intermittent signal which results in DTCs P0716 and/or P0721 setting.
3) If the common speed sensor ground circuit is lost, both sensor inputs will read the pulses from the input speed sensor when at a stop in neutral. Since the input speed sensor reads 60 teeth from the input clutch hub and the output speed sensor reads 30 teeth from the park gear, the result is an apparent speed ratio of 1:2 and may cause DTC P1794 to set.
The transmission system uses two speed sensors, one to measure input RPM and one to measure output RPM. These inputs are essential for proper transmission operation. Therefore the integrity of this data is verified through the following checks
Note. Various Gear Ratio Error DTCs will set only if the transmission slips after first achieving the correct ratio. Therefore, a transmission with no drive (or reverse) may not set any Gear Ratio Error DTC because it never achieves a correct gear ratio.
1) Once in a particular gear, if the gear ratio varies from the correct gear ratio, the corresponding in-gear DTCs P0729 and P0731-36 is set.
2) An excessive change in input or output speeds indicating an intermittent signal which results in DTCs P0716 and/or P0721 setting.
3) If the common speed sensor ground circuit is lost, both sensor inputs read the pulses from the input speed sensor when at a stop in neutral. Since the input speed sensor reads 60 teeth from the input clutch hub and the output speed sensor reads 30 teeth from the park gear, the result is an apparent speed ratio of 1:2 and may cause DTC P1794 to set.
The transmission system uses two speed sensors, one to measure input RPM and one to measure output RPM. These inputs are essential for proper transmission operation. Therefore the integrity of this data is verified through the following checks
Note. Various Gear Ratio Error DTCs will set only if the transmission slips after first achieving the correct ratio. Therefore, a transmission with no drive (or reverse) may not set any Gear Ratio Error DTC because it never achieves a correct gear ratio.
1) When in gear, if the gear ratio does not compare to a known gear ratio the corresponding in-gear DTCs P0729 and P0731-36 is set.
2) An excessive change in input or output speeds indicating an intermittent signal which results in DTCs P0716 and/or P0721 setting.
3) If the common speed sensor ground circuit is lost, both sensor inputs will read the signal from the input speed sensor at idle in neutral. Since the input speed sensor reads 60 teeth from the input clutch hub and the output speed sensor reads 30 teeth from the park gear, the result is an apparent speed ratio of 1:2 and may cause DTC P1794 to set when at a stop.
The transmission system uses two speed sensors, one to measure input RPM and one to measure output RPM. These inputs are essential for proper transmission operation. Therefore the integrity of this data is verified through the following checks
Note. Various Gear Ratio Error DTCs will set only if the transmission slips after first achieving the correct ratio. Therefore a transmission with no drive (or reverse) may not set any Gear Ratio Error DTC because it never achieves a correct gear ratio.
1) Once in a particular gear, if the gear ratio varies from the correct gear ratio the corresponding in-gear DTCs P0729 and P0731-36 is set.
2) An excessive change in input or output speeds indicating an intermittent signal which result in DTCs P0716 and/or P0721 setting.
3) If the common speed sensor ground circuit is lost, both sensor inputs will read the pulses from the input speed sensor when at a stop in neutral. Since the input speed sensor reads 60 teeth from the input clutch hub and the output speed sensor reads 30 teeth from the park gear, the result is an apparent speed ratio of 1:2 and may cause DTC P1794 to set.
The transmission system uses two speed sensors, one to measure input RPM and one to measure output RPM. These inputs are essential for proper transmission operation. Therefore the integrity of this data is verified through the following checks
Note. Various Gear Ratio Error DTCs will set only if the transmission slips after first achieving the correct ratio. Therefore a transmission with no drive (or reverse) may not set any Gear Ratio Error DTC because it never achieves a correct gear ratio.
1) Once in a particular gear, if the gear ratio varies from the correct gear ratio the corresponding in-gear DTCs P0729 and P0731-36 is set.
2) An excessive change in input or output speeds indicating an intermittent signal which results in DTCs P0716 and/or P0721 setting.
3) If the common speed sensor ground circuit is lost, both sensor inputs read the pulses from the input speed sensor when at a stop in neutral. Since the input speed sensor reads 60 teeth from the input clutch hub and the output speed sensor reads 30 teeth from the park gear, the result is an apparent speed ratio of 1:2 and may cause DTC P1794 to set.
The transmission system uses two speed sensors, one to measure input RPM and one to measure output RPM. These inputs are essential for proper transmission operation. Therefore the integrity of this data is verified through the following checks
Note. Various Gear Ratio Error DTCs will set only if the transmission slips after first achieving the correct ratio. Therefore a transmission with no drive (or reverse) may not set any Gear Ratio Error DTC because it never achieves a correct gear ratio.
1) Once in a particular gear, if the gear ratio varies from the correct gear ratio the corresponding in-gear DTCs P0729 and P0731-36 is set.
2) An excessive change in input or output speeds indicating an intermittent signal which results in DTCs P0716 and/or P0721 setting.
3) If the common speed sensor ground circuit is lost, both sensor inputs read the pulses from the input speed sensor when at a stop in neutral. Since the input speed sensor reads 60 teeth from the input clutch hub and the output speed sensor reads 30 teeth from the park gear, the result is an apparent speed ratio of 1:2 and may cause DTC P1794 to set.
When the transmission is in 2nd gear through 6th gear, the Torque Converter Clutch (TCC) can be engaged when certain conditions are met. The TCC piston is electronically modulated by increasing the duty cycle of the L/R-TCC Solenoid until the torque converter slip difference (difference between engine and transmission input speed) is within 60 RPM. Then the L/R-TCC solenoid is fully energized (FEMCC - 100% duty cycle). Torque converter slip is monitored in FEMCC to ensure adequate clutch capacity.
The Transmission Control System uses five electronically controlled solenoids that allow hydraulic fluid to be applied to various friction elements (clutches), which enables the gear requested. The continuity of each solenoid circuit is periodically tested. Each inactive solenoid is turned on for a few milliseconds, then off. Each active solenoid is turned off for a few milliseconds, then on. This pulsing of voltage to the solenoid causes an inductive spike which is sensed by the Transmission Control System. If an inductive spike is not sensed by the Transmission Control System during the continuity check, it is tested again. If the test fails three consecutive times, the appropriate Diagnostic Trouble Code (DTC) is set. If the solenoid test is run in response to a gear ratio or pressure switch error, one failure will result in setting the appropriate DTC.
The Transmission Control System uses five electronically controlled solenoids that allow hydraulic fluid to be applied to various friction elements (clutches), which enables the gear requested. The continuity of each solenoid circuit is periodically tested. Each inactive solenoid is turned on for a few milliseconds, then off. Each active solenoid is turned off for a few milliseconds, then on. This pulsing of voltage to the solenoid causes an inductive spike which is sensed by the Transmission Control System. If an inductive spike is not sensed by the Transmission Control System during the continuity check, it is tested again. If the test fails three consecutive times, the appropriate Diagnostic Trouble Code (DTC) is set. If the solenoid test is run in response to a gear ratio or pressure switch error, one failure will result in setting the appropriate DTC.
The Transmission Control System uses five electronically controlled solenoids that allow hydraulic fluid to be applied to various friction elements (clutches), which enables the gear requested. The continuity of each solenoid circuit is periodically tested. Each inactive solenoid is turned on for a few milliseconds, then off. Each active solenoid is turned off for a few milliseconds, then on. This pulsing of voltage to the solenoid causes an inductive spike which is sensed by the Transmission Control System. If an inductive spike is not sensed by the Transmission Control System during the continuity check, it is tested again. If the test fails three consecutive times, the appropriate Diagnostic Trouble Code (DTC) is set. If the solenoid test is run in response to a gear ratio or pressure switch error, one failure will result in setting the appropriate DTC.
The Transmission Control System uses five electronically controlled solenoids that allow hydraulic fluid to be applied to various friction elements (clutches), which enables the gear requested. The continuity of each solenoid circuit is periodically tested. Each inactive solenoid is turned on for a few milliseconds, then off. Each active solenoid is turned off for a few milliseconds, then on. This pulsing of voltage to the solenoid causes an inductive spike which is sensed by the Transmission Control System. If an inductive spike is not sensed by the Transmission Control System during the continuity check, it is tested again. If the test fails three consecutive times, the appropriate Diagnostic Trouble Code (DTC) is set. If the solenoid test is run in response to a gear ratio or pressure switch error, one failure will result in setting the appropriate DTC.
The Transmission system uses five pressure switches to monitor the fluid pressure in the L/R, 2C, 4C, UD and OD clutch circuits. The pressure switches are continuously monitored for the correct states in each gear as shown in chart.
The Transmission Control System tests the pressure switches when they are off. The test verifies the switches are operational (Close with pressure applied). The Transmission Control System verifies the switch closes when the corresponding element is applied. If a switch fails to close, it is re-tested. If it fails the second test, the DTC will set, the MIL will illuminate and the transmission system will default to the orderly Shutdown routine.
The Transmission system uses five pressure switches to monitor the fluid pressure in the L/R, 2C, 4C, UD and OD clutch circuits. The pressure switches are continuously monitored for the correct states in each gear as shown in chart.
Line pressure is measured by the Line Pressure Sensor (LPS) and regulation is achieved by changing the duty cycle of the Pressure Control Solenoid (PCS) controlled by the Transmission Control System, (5% duty cycle = solenoid off = Max line pressure, 62% duty cycle = solenoid on = Min line pressure). The Transmission Control System calculates the desired line pressure based on engine and transmission inputs.
The Transmission Control System calculates torque input to the transmission and uses this as the primary input for the desired line pressure calculation. This is called Torque Based Line Pressure. In addition, the line pressure is set to a preset level of 827 or 931 kPa (120 or 135 psi) during shifts and in Park or Neutral to ensure consistent shift quality. The actual line pressure is continuously being compared to the desired target line pressure. If the actual line pressure is consistently lower than the target while driving, the line pressure low DTC P0868 will set.
Line pressure is measured by the Line Pressure Sensor (LPS) and regulation is achieved by changing the duty cycle of the Pressure Control Solenoid (PCS) controlled by the Transmission Control System, (5% duty cycle = solenoid off = Max line pressure, 62% duty cycle = solenoid on = Min line pressure). The Transmission Control System calculates the desired line pressure based on engine and transmission inputs.
The Transmission Control System calculates torque input to the transmission and uses this as the primary input for the desired line pressure calculation. This is called Torque Based Line Pressure. In addition, the line pressure is set to a preset level of 827 or 931 kPa (120 or 135 psi) during shifts and in Park or Neutral to ensure consistent shift quality. The actual line pressure is continuously being compared to the desired target line pressure. If the actual line pressure is consistently higher than the highest desired line pressure used in the current gear, the line pressure high DTC P0869 will set.
The Transmission Control System tests the pressure switches when they are off. The test verifies the switches are operational (Close with pressure applied). The Transmission Control System verifies the switch closes when the corresponding element is applied. If a switch fails to close, it is re-tested. If it fails the second test, the DTC will set, the MIL will illuminate and the transmission system will default to the orderly Shutdown routine.
The Transmission system uses five pressure switches to monitor the fluid pressure in the L/R, 2C, 4C, UD and OD clutch circuits. The pressure switches are continuously monitored for the correct states in each gear as shown in chart.
The Transmission Control System tests the pressure switches when they are off. The test verifies that the switches are operational (Close with pressure applied). The Transmission Control System verifies that the switch closes when the corresponding element is applied. If a switch fails to close, it is re-tested. If it fails the second test, the DTC will set, the MIL will illuminate and the transmission system will default to the orderly Shutdown routine.
The Transmission system uses five pressure switches to monitor the fluid pressure in the L/R, 2C, 4C, UD and OD clutch circuits. The pressure switches are continuously monitored for the correct states in each gear as shown in chart.
The Transmission Control Relay is used to supply power to the solenoids and pressure switches when the transmission is in normal operating mode. The relay output is fed back to the TCM through pins 16, 17 and 36. It is referred to as "Transmission Control Relay Output". This circuit does not supply power to the TCM, it is only a sense circuit. When the relay is off, no power is supplied to the solenoids or pressure switches and the transmission is in "limp-in" or "default" mode. Note: Inadequate Transmission Control Relay Output voltage can cause DTCs P0846, P0869, P0871, P0876 or P0988 to set. This does not indicate an internal transmission or solenoid/TRS problem. Repairing the P0882 fault should eliminate the related DTCs.
The Transmission Control Relay is used to supply power (Transmission Control Output) to the Transmission Solenoid/TRS Assembly when in normal operating mode and to pins C4-19, C4-28 and C4-38 of the PCM. The purpose of the Transmission Control Relay is to allow the Powertrain Control Module (PCM) to turn off power to the Transmission Solenoid/TRS Assembly in event the transmission should need to be placed into "limp-in" mode due to a DTC.
After a PCM reset, (ignition switch turned to the run position or after cranking engine) the PCM verifies the Transmission Control Relay contacts are open by checking for voltage on the Transmission Control Relay Output circuit before the Transmission Control Relay is energized. If voltage is detected, the DTC will set.
If a vehicle loses power to the Transmission Control System, the solenoids (L/R, 2C, OD, UD, 4C) will go to their respective power off state. Some solenoids are normally vented and some are normally applied in their power off state. The transmission is designed to be in 4th gear with all of the solenoids in this state. However, if power is restored the Transmission Control System will power-up and normal operation is restored.
This code identifies that power to the Transmission Control System was restored when the gear selector is in a "Drive" position while the vehicle is moving at speeds above 32 Km/h (20 mph). This DTC does not indicate a problem with the transmission or Transmission Control System, instead, it suggests intermittent problems in the fused ignition switch output, fused B(+) or ground circuits to the PCM. Alternately, if a rolling restart maneuver is performed, the DTC can set. Therefore it is critical that this DTC be investigated if the vehicle is experiencing intermittent 4th gear operation and a subsequent return to normal operation.
The Transmission Control Relay is used to supply power to the solenoids and pressure switches (Transmission Solenoid/TRS Assembly) when the transmission is in normal operating mode. When the relay is off, no power is supplied and the transmission is in "limp-in" mode. The relay output is fed back to the PCM through pins C4-19, C4-28 and C4-38 and are referred to as "Transmission Control Relay Output".
Immediately after a controller reset (ignition key turned to the RUN position or after cranking engine), the TCM verifies the relay contacts are open by checking for no voltage at the transmission control relay output terminals. After this is verified, the voltage at the pressure switches are checked. There should be no voltage on the pressure switches at this time. The Powertrain Control Module (PCM) will activate the relay.
Line pressure is electronically controlled by the Transmission Control System and is measured by the Line Pressure Sensor (LPS). The desired line pressure is continuously being compared to the actual line pressure and is regulated by electronically changing the duty cycle of the Pressure Control Solenoid (PCS), (5% duty cycle = solenoid off = max line pressure, 62% duty cycle = solenoid on = min line pressure).
The Transmission Control System calculates the desired line pressure based on inputs from the transmission and engine. A calculated torque input to the transmission is used as the primary input of the desired line pressure calculation and is called Torque Based Line Pressure. In addition, the line pressure is set to a preset level of 1034 to 1103 kPa (150 to 160 psi) during shifts to ensure consistent shift quality.
Line pressure is electronically controlled by the Transmission Control System and is measured by the Line Pressure Sensor (LPS). The desired line pressure is continuously being compared to the actual line pressure and is regulated by electronically changing the duty cycle of the Pressure Control Solenoid (PCS), (5% duty cycle = solenoid off = max line pressure, 62% duty cycle = solenoid on = min line pressure).
The Transmission Control System calculates the desired line pressure based on transmission and engine inputs. A calculated torque input to the transmission is used as the primary input of the desired line pressure calculation and is called Torque Based Line Pressure. In addition, the line pressure is set to a preset level 827 to 931 kPa (120 to 135 psi) during shifts and in Park or Neutral to ensure consistent shift quality.
The monitored Line Pressure Sensor voltage should be between 0.35 and 4.75 volts. Any monitored voltages outside these parameters indicate a Line Pressure Sensor or wiring problem and will cause DTC P0934 or P0935 to set.
Line pressure is electronically controlled by the Transmission Control System and is measured by the Line Pressure Sensor (LPS). The desired line pressure is continuously being compared to the actual line pressure and is regulated by electronically changing the duty cycle of the Pressure Control Solenoid (PCS), (5% duty cycle = solenoid off = max line pressure, 62% duty cycle = solenoid on = min line pressure).
The Transmission Control System calculates the desired line pressure based on transmission and engine inputs. A calculated torque input to the transmission is used as the primary input of the desired line pressure calculation and is called Torque Based Line Pressure. In addition, the line pressure is set to a preset level 827 to 931 kPa (120 to 135 psi) during shifts and in Park or Neutral to ensure consistent shift quality.
The monitored Line Pressure Sensor voltage should be between 0.35 and 4.75 volts. Any monitored voltages outside these parameters indicate a Line Pressure Sensor or wiring problem and will cause DTC P0934 or P0935 to set.
The Loss of Prime Test is used to prevent transmission defaults and erroneous fault codes during temporary loss of pump prime that may occur with low transmission fluid under severe braking conditions, start-up, etc. and to point towards more subtle problems such as a plugged or cracked oil filter.
The Loss of Hydraulic Pump Prime DTC is set by a loss of hydraulic pressure in the transmission system. This condition, if sustained, will result in the vehicle being unable to move.
The Transmission Control System tests the pressure switches when they are off. The test verifies the switches are operational (Close with pressure applied). The Transmission Control System verifies the switch closes when the corresponding element is applied. If a switch fails to close, it is re-tested. If it fails the second test, the DTC will set, the MIL will illuminate and the transmission system will default to the orderly Shutdown routine.
The Transmission System uses five pressure switches to monitor the fluid pressure in the L/R, 2C, 4C, UD and OD clutch circuits. The pressure switches are continuously monitored for the correct states in each gear as shown in chart.
The PCM uses a battery backed Random Access Memory (RAM) to maintain some learned values. When the battery is disconnected the memory is lost. When the battery is restored this memory loss is detected by the Transmission Control System. The DTC is set and the learned values are initialized to known constants or previously learned values from Electronic Erasable Programmable Read Only Memory (EEPROM). This results in the reinitialization of some parameters.
The Solenoid Switch Valve (SSV) controls the direction of the transmission fluid when the L/R Solenoid is energized. The SSV will be in the downshifted position in 1st gear, directing the fluid to the L/R clutch circuit. In 2nd through 6th gears, it will be in the upshifted position and directing the fluid to the Torque Converter Clutch (TCC) control circuit.
When shifting into 1st gear, a special hydraulic sequence is performed to ensure SSV movement into the downshifted position. The L/R Pressure Switch is monitored to confirm SSV movement. If movement is not confirmed (the L/R pressure switch does not close), EMCC is inhibited until SSV operation is confirmed.
The Solenoid Switch Valve (SSV) controls the direction of the transmission fluid when the L/R Solenoid is energized. The SSV will be in the downshifted position in 1st gear, thus directing fluid to the L/R clutch circuit. In 2nd gear through 5th gear, it will be in the upshifted position and directing fluid into the Torque Converter Clutch (TCC).
When in 2nd, 2nd Prime, 3rd, 4th or 5th gear, the Torque Converter Clutch (TCC) will engage when certain conditions are met. The TCC piston is electronically modulated by increasing the duty cycle of the L/R solenoid until the torque converter slip difference (difference between engine and transmission input speed) is within 60 RPM. Then the L/R solenoid is fully energized (FEMCC / 100% duty cycle). Torque converter slip is monitored in FEMCC to ensure adequate clutch capacity.
The transmission system uses two speed sensors, one to measure input RPM and one to measure output RPM. These inputs are essential for proper transmission operation. Therefore, the integrity of this data is verified through the following checks
1) When in gear, if the gear ratio does not compare to a known gear ratio, the corresponding in-gear DTCs P0729 and P0731-36 is set.
2) An excessive change in input or output speeds indicating an intermittent signal which results in DTCs P0716 and/or P0721 set.
3) If the common speed sensor ground circuit is lost, both sensor inputs will read the signal from the input speed sensor at idle in neutral. Since the input speed sensor reads 60 teeth from the input clutch hub and the output speed sensor reads 30 teeth from the park gear, the result is an apparent speed ratio of 1:2 and may cause DTC P1794 to set when at a stop.
The volume of transmission fluid needed to apply the friction elements are continuously monitored and learned for adaptive controls. As the clutch friction material wears, the volume of fluid needed to apply the clutch increases. Certain transmission mechanical problems can cause near-zero learned volume resulting in setting a DTC. The DTC will usually set with other DTCs which indicates an internal transmission problem.
The volume of transmission fluid needed to apply the friction elements are continuously monitored and learned for adaptive controls. As the clutch friction material wears, the volume of fluid needed to apply the clutch increases. Certain transmission mechanical problems can cause near-zero learned volume resulting in setting a DTC. The DTC will usually set with other DTCs which indicates an internal transmission problem.
The volume of transmission fluid needed to apply the friction elements are continuously monitored and learned for adaptive controls. As the clutch friction material wears, the volume of fluid needed to apply the clutch increases. Certain transmission mechanical problems can cause near-zero learned volume resulting in setting a DTC. The DTC will usually set with other DTCs which indicates an internal transmission problem.
The volume of transmission fluid needed to apply the friction elements are continuously monitored and learned for adaptive controls. As the clutch friction material wears, the volume of fluid needed to apply the clutch increases. Certain transmission mechanical problems can cause near-zero learned volume resulting in setting a DTC. The DTC will usually set with other DTCs which indicates an internal transmission problem.
The volume of transmission fluid needed to apply the friction elements are continuously monitored and learned for adaptive controls. As the clutch friction material wears, the volume of fluid needed to apply the clutch increases. Certain transmission mechanical problems can cause near-zero learned volume resulting in setting a DTC. The DTC will usually set with other DTCs which indicates an internal transmission problem.
The Transmission Control System uses five electronically controlled solenoids that allow hydraulic fluid to be applied to various friction elements (clutches), which enables the gear requested. The continuity of each solenoid circuit is periodically tested. Each inactive solenoid is turned on for a few milliseconds, then off. Each active solenoid is turned off for a few milliseconds, then on. This pulsing of voltage to the solenoid causes an inductive spike which is sensed by the Transmission Control System. If an inductive spike is not sensed by the Transmission Control System during the continuity check, it is tested again. If the test fails three consecutive times, the appropriate Diagnostic Trouble Code (DTC) is set. If the solenoid test is run in response to a gear ratio or pressure switch error, one failure will result in setting the appropriate DTC. Note: This DTC is strictly an electrical fault and does not apply to any internal transmission failures.
This message is used by the Powertrain Control Module (PCM) for Electronic Range Select (ERS) operation. The ERS switch is hard wired to the Cabin Compartment Node (CCN). The CCN then sends a CAN bus message to the PCM.