Set Condition:

Set condition:  If the transmission senses the LR pressure switch closing while performing PEMCC or FEMCC. This code will be set after two unsuccessful attempts to perform PEMCC or FEMCC.

Theory of operation:  The solenoid switch valve (SSV) controls the direction of the transmission fluid when the LR/TCC solenoid is energized. SSV will be in the downshifted position in 1st gear, thus directing the fluid to the LR clutch circuits. In 2nd, 3rd, and 4th, the SSV will be in the upshifted position and directs the fluid into the torque converter clutch (TCC).

When doing PEMCC or FEMCC, the LR pressure switch should indicate no pressure if the SSV is in the TCC position. If the LR pressure switch indicates pressure while in PEMCC or FEMCC, EMCC operation is aborted and inhibited to avoid inadvertent application of the LR clutch. Partial EMCC will be attempted if the LR pressure switch does not indicate pressure. A second detection of LR pressure results in setting the code.

Transmission Effects:  At speeds above 72 Km/h (45 MPH), EMCC is inhibited. Once speed falls below 72 Km/h (45 MPH), the transmission will go into Limp-in mode and the MIL will illuminate after 5 minutes of substituted operation.

Possible causes: 

1. Valve body - Solenoid valve stuck in LR position
2. Intermittent short to ground or open circuit in LR Pressure Switch Sense circuit (with code 24 only)
3. Solenoid pack (with code P0841(24) only)
4. TCM (with code P0841(24) only)

Name of code: P1793(48) - TRD Link Communication Error 

Set condition:  This code is set when the TCM sends multiple torque reduction messages to the PCM and the TCM does not receive a response from the PCM.

Theory of operation:  During high torque shifts the TCM will send a message requesting that the PCM reduce engine power until the shift is completed. This message is sent from the TCM to the Powertrain Control Module across the Torque Management Request Sense Circuit. The PCM will acknowledge the TCM request by sending a message across the PCI bus within a specific amount of time. The TRD Link communication is also tested periodically for operation whenever the engine is running and the vehicle is not moving with zero degrees throttle.

Transmission Effects:  Maximum throttle angle used by TCM will be 54 degrees. As a result a customer my complain about loss of performance or of short shifting when driving aggressively.

Possible causes: 

1. Sticky Throttle Position Sensor (TPS)
2. Wiring or Connector problems in the Torque Management Request Sense Circuit
3. PCM
4. TCM

Name of code: P0736(50) - Gear Ratio Error in Reverse 

P0731(51) - Gear Ratio Error in 1st 

P0732(52) - Gear Ratio Error in 2nd 

P0733(53) - Gear Ratio Error in 3rd 

P0734(54) - Gear Ratio Error in 4th 

P0715(56) - Input Speed Sensor Error 

P0720(57) - Output Speed Sensor Error 

P1794(58) - Speed Sensor Ground Error 

Set condition:  This code is set if the gear ratio is not correct for a period of time.

• Codes 50 through 54 sets if the ratio of the input RPM (Nt) to the output RPM (No) does not match the given gear ratio.
• Code 56 sets if there is an excessive change in input RPM in any gear
• Code 57 sets if there is an excessive change in output RPM in any gear
• Code 58 sets after a TCM reset in neutral and Nt/No equals a ratio of input to output of 2.50

A hard code sets within 3 seconds, an intermittent code sets within 15 seconds.

Theory of operation:  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 trouble code is set (codes 50 through 54).
2. An excessive change in input or output speeds indicating signal intermittent will result in codes 56 and/or 57 being set.
3. After a TCM reset in neutral, observing erratic output and input speed sensor signals indicates a loss of the common speed sensors ground. This sets a code 58.

Transmission Effects:  The transmission will not go into Limp-in mode until three gear ratio error events occur in a given key start also the MIL will illuminate after 5 minutes of substituted operation. This allows for intermittent problems to correct themselves without opening the relay. However, if a gear ratio error develops, a code is always set, but if the condition corrects itself the transmission will continue without requiring the ignition key to be cycled on and off. Many different events could occur given the range of failures possible for codes 50 through 58. The following are a few examples:

• Codes 51, 52, 53, 54, 56, and 57 at speeds above 72 Km/h (45 MPH) - The appropriate code is set, EMCC is aborted and current gear is maintained. If while still traveling above 72 Km/h (45 MPH), the gear ratio becomes valid again, EMCC will reengage and normal operation will resume. If the gear ratio becomes intermittent and recovers three times in a given key start, the current gear will be maintained and EMCC inhibited, then the transmission will go into Limp-in mode if throttle is applied below 72 Km/h (45 MPH) or at 35 Km/h (22 MPH) with closed throttle.
• Codes 51, 52, 53, 54, 56, and 57 at speeds between 35 and 72 Km/h (22 and 45 MPH) - If one of these codes is set between 35 and 72 Km/h (22 and 45 MPH), the current gear will be maintained until the gear ratio problem corrects itself. If throttle is applied, the trans will go to 2nd gear. If this happens and the gear ratio problem goes away, normal operation will resume. If three gear ratio problems are identified in a given key start, the current gear will be frozen until throttle is applied. The transmission will then go into Limp-in mode with throttle applied at speeds between 35 and 72 Km/h (22 and 45 MPH)
• Codes 51, 52, 53, 54, 56, and 57 at speeds below 35 Km/h (22 MPH) - If a gear ratio problem is identified below 35 Km/h (22 MPH), the transmission will immediately substitute second gear for the current gear. If the gear ratio problem goes away, normal operation will resume. If three gear ratio problems are identified in a given key start, the transmission will go into Limp-in mode.

Possible causes: 

Code P0736(50) - Excludes geartrain failures which should be obvious upon disassembly

1. If code P0944(35) is also set, follow diagnostic procedure for code P0944(35) first
2. Valve body - #1 ball check or LR switch valve sticking - may also set code P0731(51)
3. Speed sensor or associated wiring - may also set codes P0731(51), P0715(56), or P0720(57)
4. Failed or slipping LR clutch - may also set code P0731(51)
   • LR seal leakage (Intermittent no drive or reverse)
   • Sticky LR accumulator seals (Intermittent no drive or reverse)
5. Failed reverse clutch (hard code)
   • OD/Rev lip seal leakage
   • Worn reaction shaft support seal rings
   • Snap ring out of position

Code P0731(51) - Excludes geartrain failures which should be obvious upon disassembly

1. If code P0944(35) is also set, follow diagnostic procedure for code P0944(35) first
2. Valve body - #1 ball check or LR switch valve sticking - may also set code P0736(56) or have no Reverse
3. Speed sensor or associated wiring - may also set codes P0736(50), P0715(56), or P0720(57)
4. Failed or intermittent slipping UD clutch - may also set P0732(52), or P0733(53)
   • UD seal leakage (intermittent)
   • Worn input clutch hub bushing (hard code at heavy throttle)
   • Sticky UD accumulator seals (intermittent)
   • Worn reaction shaft support seal rings (hard code at heavy throttle)
   • Solenoid pack (UD pressure in 4th gear)
5. Failed or slipping LR clutch - may also set code P0736(56) or have no Reverse
   • LR seal leakage (Intermittent)
   • Sticky LR accumulator seals (Intermittent)

Code P0732(52) - Excludes geartrain failures which should be obvious upon disassembly

1. If code P0944(35) is also set, follow diagnostic procedure for code P0944(35) first
2. Failed or slipping 2/4 clutch - may also set code P0734(54)
   • 2/4 seal leakage (intermittent)
   • Sticky accumulator seals (intermittent)
3. Failed or intermittent slipping UD clutch - may also set code P0731(51) and/or P0733(53)
   • UD seal leakage (intermittent)
   • Worn input clutch hub bushing (hard code at heavy throttle)
   • Sticky UD accumulator seals (intermittent)
   • Worn reaction shaft support seal rings (hard code at heavy throttle)
   • Solenoid pack (UD pressure in 4th gear)

Code P0733(53) - Excludes geartrain failures which should be obvious upon disassembly

1. If code P0944(35) is also set, follow diagnostic procedure for code P0944(35) first
2. Failed or slipping OD clutch - may also set code P0734(54)
   • OD and Reverse inner and outer lip seal leakage (usually hard code)
   • Sticky OD accumulator seals (intermittent)
   • Worn reaction shaft support seal rings (hard code at heavy throttle)
   • Broken OD/UD tapered snap ring - (hard code at heavy throttle)
3. Failed or intermittent slipping UD clutch - may also set code P0731(51) and/or P0732(52)
   • UD seal leakage (intermittent)
   • Worn input clutch hub bushing (hard code at heavy throttle)
   • Sticky UD accumulator seals (intermittent)
   • Worn reaction shaft support seal rings (hard code at heavy throttle)
   • Solenoid pack (UD pressure in 4th gear)

Code P0734(54) - Excludes geartrain failures which should be obvious upon disassembly

1. If code P0944(35) is also set, follow diagnostic procedure for code P0944(35) first
2. Failed or slipping OD clutch - may also set code P0733(53)
   • OD and Reverse inner and outer lip seal leakage (usually hard code)
   • Sticky OD accumulator seals (intermittent)
   • Worn reaction shaft support seal rings (hard code at heavy throttle)
   • Broken OD/UD tapered snap ring - (hard code at heavy throttle)
3. Failed or slipping 2/4 clutch - may also set code P0732(52)
   • 2/4 seal leakage (intermittent)
   • Sticky accumulator seals (intermittent)

Codes P0715(56) and P0720(57)

1. Failed input or output speed sensor (intermittent or hard code)
2. Shorted or open wiring between TCM and speed sensor(s) (intermittent)
3. Connector problems at 60 TCM connector and/or speed sensor connector

Code P1794(58)

1. Open or shorted speed sensor ground (speed sensor ground is different from chassis ground)
2. Open or shorted Temperature Sensor wiring to TRS
3. TRS - Will also set code P1799(74)
4. TCM

Name of code: P1797(71)- Manual Shift Overheat 

Set condition: 

1. If the engine temperature exceeds 124 C (255°F) while operating in AutoStick mode.
2. If the transmission temperature exceeds 135°C (275°F) while in AutoStick mode

Theory of operation:  Transmission and engine temperatures are monitored during vehicle operation. If conditions occur causing the engine or transmission to overheat, the AutoStick mode will be canceled, and a code will be set.

Transmission Effects:  The 3 position shift schedule that is used in non-AutoStick applications is substituted while operating in the AutoStick gear selector position. No Limp-in mode occurs.

Possible causes: 

1. Engine overheat - refer to ENGINE COOLING SYSTEM OVERHEATING for diagnosis and repair
2. Transmission Overheat
   • Restricted transmission cooling system
   • Transmission fluid overfilled
   • Radiator fan not functioning properly
   • Extended driving in low gear

Name of code: P0897(73) - Worn Out/Burnt Transmission Fluid 

Set condition:  The code will be set if vehicle shudder is detected 20 times when the A/C clutch is cycled.

Theory of operation:  While in 3rd or 4th gear FEMCC and just before the A/C clutch engages, the Powertrain Control Module (PCM) requests the Transmission Control Module (TCM) to momentarily establish PEMCC operation. If vehicle shudder is detected during the FEMCC to PEMCC transition, a counter is incremented. If the count reaches 20, the trouble code is set. The driver may then notice harsh bumps when the A/C clutch is being cycled, but vehicle shudder will be eliminated. After 35 OBDII (EURO STAGE III OBD) warm-up starts or if the code is cleared, PEMCC will be reactivated to see if shudder is still present. If one shudder event occurs, the code will be reset. Clearing the code and running battery disconnect with the DRBIII® is the only way to reset the shudder counter from 20 back to zero.

Transmission Effects:  This code does not cause the transmission to go into Limp-in mode. However, once the code is set, FEMCC to PEMCC operation before the A/C clutch engagement will be disabled for 35 OBDII (EURO STAGE III OBD) warm up starts.

Possible causes: 

1. Degraded transmission fluid
2. Wheels severely out of alignment
3. Internal torque converter problem

Name of code: P0218(75) - High Temperature Operation Activated. 

Set condition:  Immediately once the Overheat Shift Schedule is activated.

Theory of operation:  If the transmission oil temperature rises above 115°C (240°F), the overheat shift schedule is activated. Refer to TRANSMISSION OPERATION AND SHIFT SCHEDULING AT VARIOUS OIL TEMPERATURES  as a function of Transmission Oil Temperature and the code is set. The DTC is an information code only and is being set to aid the technician in determining root cause of a customer driveability issue. The code 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 should be added to the vehicle if the customer regularly drives in a manner that overheats the transmission. Extended operation above 115°C (240°F) will reduce the durability of the transmission and should be avoided. Correcting the cooling system malfunction or installing an additional transmission oil cooler will improve transmission durability especially for customers who operate in city/construction stop and go traffic, tow trailers regularly, drive aggressively in low gear or drive regularly in mountainous areas.

Transmission effects:  Information only code. - Overheat shift schedule was activated, no Limp-in condition occurs. 2nd gear partial EMCC above 40 Km/h (25 MPH), 3rd gear EMCC from 45-69 Km/h (28-43 MPH), delayed 3-4 upshift at 69 Km/h (43 MPH), early 4-3 coastdown at 66 Km/h (41 MPH), EMCC operation under all conditions above 40 Km/h (25 MPH) except at closed throttle or 1st gear.

Possible causes: 

• Transmission Overfilled with Oil
• Engine cooling fan failure
• Engine thermostat stuck closed
• Radiator corroded or packed with dirt
• Transmission Oil Cooler Plugged
• Customer driving pattern requires additional transmission cooling

Name of code: P0884(76) - Power Up at Speed 

Set condition:  If the TCM powers up while in the "Drive" position and the vehicle is going above 32 Km/h (20 MPH), the code is set.

Theory of Operation:  If a vehicle loses power to the TCM, the vehicle will go to the 2nd gear mode since there is no power available to control the transmission solenoids. However if power is restored, the TCM will power-up and normal operation will be restored. This DTC identifies that power to the TCM was restored when the gear selector was in a "Drive" position while the vehicle was moving at speeds above 32 Km/h (20 MPH). If someone shifts to Neutral and cycles the ignition key and quickly shifts to "Drive" while moving before the TCM comes out of its START ROUTINE, the DTC can be set. Therefore it is critical that this DTC diagnosis repair procedure should only be used if the vehicle is experiencing intermittent 2nd gear operation and subsequently a return to normal operation during normal driving.

Transmission Effects:  No Limp-in condition. The DTC is for information only when trying to diagnosis intermittent 2nd gear operation and subsequently a return to normal operation.

Possible causes: 

• No Problem if vehicle is started in "neutral" at speeds above 32 Km/h (20 MPH) and shifted quickly to "Drive" before TCM comes out of the START ROUTINE.

FOR INTERMITTENT 2ND GEAR OPERATION AND THEN A SUBSEQUENT RETURN TO NORMAL OPERATION WITHOUT CYCLING THE IGNITION KEY 

• Intermittent Direct Battery connection between TCM (60-way pin 56) and battery.
• Intermittent Fused Ignition Switch Output between TCM (60-way pin 11) and ignition switch.
• Intermittent Ground to TCM (60 way pins 53 and 57).

Name of code: P1687(77) - No Communication with the MIC 

Set condition:  If no PCI bus messages are received from the Mechanical Instrument Cluster (MIC) for 25 seconds.

Theory of operation:  The TCM communicates with the MIC using the PCI bus. It relies on certain information to function properly. The TCM continuously monitors the PCI bus to check for messages broadcast from the PCM.

Transmission effects:  Possible improper TCM AutoStick configuration.

Possible causes: 

1. Open or shorted PCI bus circuit from MIC
2. MIC
3. TCM (If other communications codes are stored in the TCM only)

Name of code: P1652(78) - Serial Communication Link Malfunction 

Set condition:  If no PCI bus messages are received by the Transmission Control Module (TCM) for 10 seconds.

Theory of operation:  The TCM communicates with the other modules in the vehicle using the PCI bus. It relies on certain information to function properly. The TCM continuously monitors the PCI bus to check for messages broadcast from the certain modules.

Transmission Effects:  Possible improper TCM AutoStick configuration and delayed 3-4 shifts. No EMCC and early 3-4 shifts for a few minutes after engine is started.

Possible causes: 

1. Open or shorted PCI bus circuit from BCM
2. TCM

Name of code: P0562(79) Low Battery Voltage 

Set condition:  If the voltage sensed at the Transmission Control Relay Output circuit (pins 16 and 17 at TCM) for 15 seconds.

Theory of operation:  The Transmission system requires sufficient battery voltage in order to energize the transmission solenoids. The TCM continuously monitors the voltage available to the solenoids.

Transmission effects:  At speeds above 72 Km/h (45 MPH) the transmission system will default to neutral. Below 72 Km/h (45 MPH) the transmission system will default to Limp-in mode and the MIL will illuminate after 5 minutes of substituted operation. Manual gear selection of Park, Reverse, Neutral and Second will be available.

Possible causes: 

1. Charging system problem
2. Poor/High resistance connection between TCM and Battery/Alternator
3. TCM pin 16 and 17 high resistance or poor connection
4. TCM ground pins 53 and 57 high resistance or poor connection
5. High resistance in Transmission Control Relay contacts
6. TCM

Name of code: P0711(7A) - Transmission temperature sensor performance 

Set condition:  A temperature reading of 80°F is not reached in the specified period of time

Theory of operation:  The temperature sensor (thermistor) is used to sense the temperature of the transmission fluid. Transmission fluid temperature can affect shift quality, torque converter lockup, and when and if some diagnostics are run. A failed temperature sensor could affect the OBD II diagnostics, therefore when a fault is detected in the temperature sensor circuit, transmission temperature will be based on a calculated temperature value.

Transmission Effects:  When the fault is set, calculated temperature is substituted for measured temperature, however the fault code is stored only after three consecutive occurrences of the fault.

Possible causes: 

1. Temperature sensor
2. Temperature sensor wiring circuit.
3. Internal controller

Name of code: P0712(7B) - Transmission temperature sensor low 

Set condition:  Sensor output voltage less than 0.078v.

Theory of operation:  The temperature sensor (thermistor) is used to sense the temperature of the transmission fluid. Transmission fluid temperature can affect shift quality, torque converter lockup, and when and if some diagnostics are run. A failed temperature sensor could affect the OBD II diagnostics, therefore when a fault is detected in the temperature sensor circuit, transmission temperature will be based on a calculated temperature value.

Transmission effects:  When the fault is set, calculated temperature is substituted for measured temperature, however the fault code is stored only after three consecutive occurrences of the fault.

Possible causes: 

1. Temperature sensor
2. Temperature sensor wiring circuit.
3. Internal controller

Name of code: P0713(7C) - Transmission temperature sensor high 

Set condition:  Sensor output voltage greater than 4.94v.

Theory of operation:  The temperature sensor (thermistor) is used to sense the temperature of the transmission fluid. Transmission fluid temperature can affect shift quality, torque converter lockup, and when and if some diagnostics are run. A failed temperature sensor could affect the OBD II diagnostics, therefore when a fault is detected in the temperature sensor circuit, transmission temperature will be based on a calculated temperature value.

Transmission effects:  When the fault is set, calculated temperature is substituted for measured temperature, however the fault code is stored only after three consecutive occurrences of the fault.

Possible causes: 

1. Temperature sensor
2. Temperature sensor wiring circuit.
3. Internal controller

Name of code: P0714(7D) - Transmission temperature sensor intermittent