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NAME OF CODE: P0604, P0605, P0613(11, 13, 16, 17 or 45) - Internal ControllerWhen Monitored: Whenever the key is in the Run or Run/Start position.
Set Condition: This code is set whenever Transmission Control Module (TCM) senses an internal error
Theory of Operation: The TCM is constantly monitoring it's internal processor. If an internal problem is detected, this DTC will be set. This DTC can also be set by a bad ground to the TCM and/or Trans Control Relay. In fact, this DTC is rarely set due to a TCM error, it is usually set by a poor ground.
Transmission Effects: The MIL will illuminate (this DTC can take up to five minutes of problem identification before illuminating the MIL) and the transmission system will default to the Immediate Shutdown routine.
Possible Causes:
- TCM ground circuit. (check main ground attachment to engine block)
- Relay ground circuit. (check main ground attachment to engine block)
- TCM
NAME OF CODE: P1684(12) - Battery was Disconnected (Info Only)
When Monitored: Whenever the key is in the Run or Run/Start position.
Set Condition: This code is set whenever Transmission Control Module (TCM) is disconnected from battery power (B+) or ground. It will also be set during the DRBIII Quick Battery Disconnect procedure.
Theory of Operation: A battery backed RAM (Random Access Memory) is used to maintain some learned values. When the battery B(+) is disconnected, the memory is lost. When the B(+) is restored, this memory loss is detected by the TCM. The code is set and the learned values are initialized to known constants or previously learned values from EEPROM (Electronic Erasable Programmable Read Only Memory). This results in the reinitialization of some parameters.
Transmission Effects: Loss of trouble code data. The Transmission system will default to the Immediate shutdown routine if power is lost while operating the vehicle. Normal operation is resumed if the power is restored during the same key start.
Possible Causes:
- Battery voltage removed from TCM (Fused B+)
- TCM disconnected
- Dead Battery
- Low battery voltage during cranking
- Quick Battery Disconnect by DRBIII or MDS
- Bad TCM ground circuit.
NAME OF CODE: P0891(14) - Relay Always On
When Monitored: When ignition key is turned from "OFF" position to "RUN" position and/or ignition key is turned from "CRANK" position to "RUN" position.
Set Condition: This code is set if the Transmission Control Module (TCM) senses greater than 3 volts at the Trans Control Relay Output terminal(s) of the TCM prior to the TCM energizing the relay.
Theory of Operation: 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 and pressure switches, and the transmission is in "limp-in" or "default" mode.
Transmission Effects: The MIL will illuminate (this DTC can take up to five minutes of problem identification before illuminating the MIL) and the transmission system will default to the Immediate Shutdown routine.
Possible Causes:
- Short to voltage in the Transmission Solenoid/TRS Assembly (internal into any solenoid control circuit)
- Short to voltage on any solenoid control circuit
- Relay contacts stuck together.
- Short to voltage in Transmission Control Relay output circuit(s).
- Short to voltage in Transmission Relay Control circuit.
- Short to voltage on any pressure switch sense circuit.
- TCM connector problems.
- TCM.
NAME OF CODE: P0888(15) - Relay Output Always Off
When Monitored: Continuously
Set Condition: This code is set when less than 3 volts are present at any transmission control relay output (pins 16,17 or 36) circuits at the Transmission Control Module (TCM) when the TCM is energizing the relay.
Theory of Operation: 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 and pressure switches, and the transmission is in "limp-in" or "default" mode.
After a controller reset (ignition key turned to the "run" position or after cranking engine), the controller energizes the relay. Prior to this the TCM verifies that the contacts are open by checking for no voltage at the switched battery terminals. After the relay is energized, the TCM monitors the terminals to verify that the voltage is greater than 3 volts.
Transmission Effects: The MIL will illuminate (this DTC can take up to five minutes of problem identification before illuminating the MIL) and the transmission system will default to the Immediate Shutdown routine.
Possible Causes:
- Transmission Control Relay (intermittent relay function caused by oxidized or contaminated relay contacts)
- Short to ground or open circuit in the transmission control relay output circuit(s)
- Short to ground or open circuit in the Transmission Solenoid/TRS assembly
- TCM connector problem
- Relay connector problem
- Relay Ground circuit
- TCM Ground circuit(s)
- TCM
NAME OF CODE: P0725(18) - Engine Speed Sensor Circuit
When Monitored: Continuously with engine running.
Set Condition: This code is set when the engine speed calculated by the Transmission Control Module (TCM) is less than 390 RPM, while the engine speed broadcast by the PCM is greater than 383 RPM. The DTC also sets if the calculated engine speed is greater than 8000 RPM for more that 2.0 seconds.
Theory of Operation: The TCM uses the crank sensor signal to calculate engine RPM. The TCM uses RPM data from the PCM which is broadcast over the communication bus to determine if the engine is running. The TCM continuously compares calculated engine speed to the engine RPM reported on the bus, by the PCM, so that loss of crankshaft position sensor signal to the TCM will not be misinterpreted as engine not running.
Transmission Effects: The MIL will illuminate (this DTC can take up to five minutes of problem identification before illuminating the MIL) and the transmission system will default to the Logical Shutdown routine.
Possible Causes:
- Open or short in engine speed sensor circuit. (Crank sensor signal)
- TCM connector problems (Crank sensor signal or sensor ground terminals)
- Open or short in sensor ground circuit
- Low engine idle speed
- TCM
- PCM.
NAME OF CODE: P1694(19) - Bus Communication with Engine Module
When Monitored: Continuously with key on.
Set Condition: If no bus messages are received from the Powertrain Control Module (PCM) for 10 seconds.
Theory of Operation: The TCM communicates with the PCM using the communication bus. It relies on certain information to function properly. The TCM continuously monitors the bus to check for messages broadcast from the PCM.
Transmission Effects: Delayed 3-4 shifts. No EMCC and early 3-4 shifts for a few minutes after engine is started. Generally poor shift quality.
Possible Causes:
- Open or shorted bus circuit
- TCM
- PCM
NAME OF CODE: P0706(28) - Check Shifter Signal
When Monitored: Continuously with the key on.
Set Condition: Any occurrences of an invalid PRNDL code which lasts for more than 0.028 second.
45RFE / 545RFE TRS Switch States:
Shift Lever Error Codes:
Theory of Operation: The C1 through C5 (TRS T1, TRS T2, TRS T3, TRS T41, and TRS T42) sense circuits communicate the shift lever position to the TCM. Each circuit is terminated at the transmission with a switch. Each switch can be either open or closed, depending on the shift lever position. The TCM can decode this information and determine the shift lever position. Each shift lever position has it own unique combination of closed and open switches. This is called a PRNDL code. There are 5 switches, therefore: there are many possible combinations of open and closed switches (codes). There are 12 valid codes, two for neutral, one for each other gear position (5), and five temporary (transition zone) codes. The remainder of the codes should never occur, these are called invalid codes.
NOTE: If you are using the transmission simulator and do not push the OD off button in the vehicle when performing a Shift Lever position test, you will receive a code 11 OD lockout stuck open
Transmission Effects and Possible Causes: (This code alone will not illuminate the MIL)
- Excessive metal debris in the transmission oil pan
- Worn Code Plate. Check for heavy wearing by TRS switch contacts
- Intermittent C1 through C5 (T1, T2, T3, T41 or T42) circuits. Check for corrosion, terminal push-outs or spread terminals at 60-way TCM connector and/or 23-way transmission connector.
- TRS connector not plugged in, or unplugged with the key on.
- TRS C1 through C5 (T1, T2, T3, T41, or T42) circuit(s) are either open, shorted to ground, or shorted to 12 volts.
- TRS
- TCM
NAME OF CODE: P0120(29) - Throttle Position Signal
When Monitored: Whenever the engine is running.
Set Condition: This code is set if the throttle angle goes out of range or changes erratically i.e. faster than the throttle body motion should occur.
Theory of Operation: The Transmission Control Module (TCM) receives the throttle position signal from the Throttle Position Sensor (TPS). The TPS has a 5-volt pull up supplied from the Powertrain Control Module (PCM). The signal is checked for out-of-range as well as intermittent (excessive signal changes).
Transmission Effects: The MIL will illuminate, the transmission system will not go into limp-in mode. The TCM will use a "calculated throttle angle" supplied by the PCM over the communication bus. If the communication bus is unavailable, the TCM will use a default throttle angle of 24( degrees for the key start in which the code was set. The TCM will try to use the TPS signal again on the next key start. The vehicle may experience extremely erratic transmission shifting just prior to setting the code. If the intermittent does not last long enough to set the code, the customer will say that the transmission violently hunts between gears.
Possible Causes:
- Open or shorted TPS signal and/or ground circuits
- TCM connector problems
- Failed TPS or TPS connector (Check PCM DTC's)
- PCM
- TCM
NAME OF CODE: P0944(35) - Loss Of Prime
When Monitored: If the transmission is slipping in any forward gear and all the pressure switches are indicating no pressure, a loss of prime test is run.
Set Condition: If the transmission begins to slip in any forward gear, and all pressure switches are open, a loss of prime test begins. All available elements are momentarily turned on by the Transmission Control Module (TCM) to see if pump prime exists. The code is set if none of the pressure switches respond. The TCM will continue to run the loss of prime test until pump pressure returns. Note: Loss of Prime test is not run when transmission temperature is "Super Cold".
Theory of Operation: The loss of prime test is used to prevent transmission defaults, which can be caused by a lack of pump prime.
Transmission Effects: Vehicle will not move or transmission slips. Normal operation will continue if pump prime returns.
Possible Causes:
- Low transmission fluid level
- Transmission fluid filter improperly installed (Seal installed onto filter neck instead of into pump bore, seal not fully seated against pump bore housing, filter neck not engaged into pump, bolts loose or O-ring missing or damaged)
- Transmission fluid filter clogged, damaged or cracked
- Transmission has massive hydraulic leak (valve body pipe plugs missing, etc.)
- Transmission oil pump
- Transmission oil pump drive is sheared or damaged
- PRNDL indicates a valid OD code in the hydraulic reverse position
NAME OF CODE: P1790(36) - Fault Immediately After Shift
When Monitored: When a speed ratio error DTC (50 through 55) is stored.
Set Condition: This code is set if the associated speed ratio code is stored within 1.3 seconds after a shift.
Theory of Operation: This code will only be stored along with a 50 series code. If this code is set, it indicates a probable hydraulic (line pressure) or mechanical problem exists. When this code is set, diagnosing the transmission should be based on the associated speed ratio code and mechanical causes should be considered first.
Transmission Effects: None
Possible Causes:
- Mechanical causes as listed under associated speed ratio code.
- Inadequate line pressure
- Cut or damaged clutch piston seals
NAME OF CODE: P1775(37) - Solenoid Switch Valve Latched in TCC Position
When Monitored: During an attempted shift into 1st gear.
Set Condition: This code is set if 6 unsuccessful attempts are made to get into 1st gear, with transmission temp above 27°C (80°F), in one given key start.
Theory of Operation: The solenoid switch valve (SSV) controls the direction of the transmission fluid when the LR solenoid is energized. The SSV will be in the downshifted position in 1st gear, thus directing the fluid to the L-R clutch circuit. In 2nd, 3rd, and 4th, it will be in the upshifted position and directs the fluid into the torque converter clutch (TCC).
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.
Transmission Effects: Transmission will have 1st gear, and no EMCC operation. The MIL will illuminate after 5 minutes of no EMCC operation.
Possible Causes:
- Valve body - Solenoid Switch Valve stuck in TCC position
- L-R solenoid armature or plunger broken should also set DTC P0841 (81) and often sets P0740(38)
- Solenoid malfunction - may also set code P0841(81)
- L-R Pressure Switch Sense circuit shorted to battery
- High idle speed
- PRNDL indicates a valid OD code in the hydraulic reverse position
NAME OF CODE: P0740(38) - Torque Converter Clutch Control Circuit
When Monitored: During Electronically Modulated Converter Clutch (EMCC) Operation
Set Condition: The code will be set if one of the following events happens three times in a given
key start, at a throttle angle less than 30(a) With the transmission in EMCC, the TCC/L-R solenoid achieves the maximum duty cycle and is still unable to pull the engine speed within 60 RPM of input speed (b) With the transmission in FEMCC, the TCC RPM (Engine speed Input speed) is more than 100 RPM for 7.2 seconds.
Theory of Operation: When in 2nd, 2nd Prime, 3rd, or 4th 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 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.
Transmission Effects: EMCC will still be available after code is set. MIL will illuminate after 5 minutes of accumulated slip in FEMCC. The transmission will attempt normal operation (no limp-in) even after the MIL is illuminated.
Possible Causes:
- Cut converter hub O-ring and/or failed torque converter - both should be replace during a rebuild with code P0740(38) present.
- Sticky CC Regulator valve
NAME OF CODE: P1776(47) - Solenoid Switch Valve (SSV) Latched in L-R Position
When Monitored: Continuously when doing partial or full EMCC (PEMCC or FEMCC)
Set Condition: If the transmission senses the L-R pressure switch closing while performing PEMCC or FEMCC. This code will be set after four 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 solenoid is energized. SSV will be in the downshifted position in 1st gear, thus directing the fluid to the L-R 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 L-R pressure switch should indicate no pressure if the SSV is in the TCC position. If the L-R pressure switch indicates pressure while in PEMCC or FEMCC, EMCC operation is aborted and inhibited to avoid inadvertent application of the L-R clutch. Partial EMCC will be attempted if the L-R pressure switch does not indicate pressure. Four occurences of detection of L-R pressure results in setting the code.
Transmission Effects: EMCC is inhibited and the transmission system will default to the Orderly Shutdown routine. (this DTC can take up to five minutes of problem identification before illuminating the MIL).
Possible Causes:
- Valve body - Solenoid Switch Valve stuck in L-R position
- Intermittent short to ground or open circuit in L-R Pressure Switch Sense circuit (with code P0841 only)
- Solenoid/TRS assembly (with code P0841(81) only)
- TCM (with code P0841(81) only)
NAME OF CODE: P1793(48) - Torque Reduction (TRD) Link Communication Error
When Monitored: During torque managed shifts (Throttle angle above 54 degrees). This system is also tested whenever the vehicle is stopped and the engine speed is below 1000 RPM.
Set Condition: This code is set when the Transmission Control Module (TCM) sends two subsequent torque reduction messages to the Powertrain Control Module (PCM) via the TRD link circuit and does not receive a confirmation from the PCM over the communication bus.
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 PCM across the Torque Management Request Sense Circuit. The PCM will acknowledge the TCM request by sending a confirmation message across the communication bus. 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 may complain about loss of performance, short shifting when driving aggressively, and/or normal shifting and WOT shifts may be harsh.
Possible Causes:
- Sticky Throttle Position Sensor (TPS)
- Wiring or Connector problems in the Torque Management Request Sense Circuit
- Bus communication problems.
- PCM
- 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
P1736(55) - Gear Ratio Error in 2nd Prime
P0715(56) - Input Speed Sensor
P0720(57) - Output Speed Sensor
P1794(58) - Speed Sensor Ground
P0735(59) - Gear Ratio Error in 4th Prime
When Monitored: The transmission gear ratio is monitored continuously while the transmission is in gear.
Set Condition: This code is set if the gear ratio is not correct for the current gear.
- Codes 50 through 59 sets if the ratio of the input RPM (Nt) to the output RPM (No) does not match the current 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 2.00
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 59).
2. An excessive change in input or output speeds indicating signal intermittent will result in codes 56 and/or 57 being 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 has 60 teeth and the output speed sensor has 30 teeth, this results in a ratio of 2.00.
Transmission Effects: If a gear ratio error develops, the appropriate code is set as a one trip failure and the 5 minute Intelligent Recovery Timer (IRT) is started. The transmission will then substitute a 1-3 or 3-1 shift to a different gear for the one in which the problem was identified. For example , if a problem is identified while in first gear, the transmission will shift to third gear. The IRT is only counting up while the transmission is substituting one gear for another. Using the previous example, if the vehicle continued down the road and shifted to fourth gear for a long period of time, the IRT would have only counted the time that the transmission was in third gear instead of second. The MIL will illuminate (this DTC can take up to five minutes of problem identification before illuminating the MIL). The transmission system will default to the Logical Shutdown without Recovery routine after 5 minutes of substituted gear operation or if three gear ratio error events occur in a given key start.
Possible Causes:
Code P0736(50) - Excludes gear train failures which should be obvious upon disassembly
- If code P0944(35) or any line pressure DTC's are set, diagnose these first
- Valve body - # 3 check ball
- L-R switch valve sticking - may also set code P0731(51)
- Speed sensor or associated wiring - may also set codes P0731(51), P0715(56), or P0720(57)
- Multi Select Solenoid sticking or leaking
- Failed or slipping L-R clutch - may also set code P0731(51)
- L-R seal leakage (Intermittent no drive or reverse)
- Sticky L-R accumulator seals (Intermittent no drive or reverse)
- Failed reverse clutch (hard code) - OD/Rev lip seal leakage - Worn reaction shaft support seal rings