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Transmission Effects and possible causes:
(This DTC alone will not illuminate the MIL)
^ TRS connector not plugged in
^ TRS T1, T2, T3, T41, or T42 circuit(s) are either open, shorted to ground, or shorted to 12 volts
^ TRS
^ TCM
^ Worn Code Plate. Check for heavy wearing by TRS switch contacts Intermittent 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.
^ These same symptoms may occur without the DTC 28 getting set. It is possible that the invalid DTC that was sensed by the TCM only occurred once or twice during the given ignition key start and/or did not last for longer than 0.1 second.

Name of DTC: P-0120(29) - Throttle Position Sensor
When monitored: Whenever the engine is running.
Set condition: This DTC is set if the throttle angle goes out of range or if throttle angle changes abruptly (i.e.: faster than the throttle body motion could 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 intermittence (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 ignition start in which the DTC 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 DTC. If the intermittent condition does not last long enough to set the DTC, the customer may say that the transmission violently hunts between gears.
Possible causes:
^ Open or shorted TPS signal and/or ground circuits
^ TCM connector problems
^ TPS or TPS connector (Check PCM DTC's)
^ PCM
^ TCM

Name of DTC: P-1791(35) - Loss Of Prime
When monitored: If the transmission is slipping in any forward gear and the pressure switches are not indicating pressure, a loss of prime test is run.
Set condition: If the transmission begins to slip in any forward gear, and the pressure switch or switches that should be closed for a given gear 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 DTC is set if none of the pressure switches respond. The TCM will continue to run the loss of prime test until pump pressure returns.
Theory of operation: The loss of prime test is used to prevent transmission defaults that 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
^ PRNDL indicates a valid OD DTC in the hydraulic reverse position
^ Transmission fluid filter clogged or damaged
^ Transmission fluid filter improperly installed (Bolts loose or O-ring missing)
^ Oil pump

Name of DTC: P-1790(36) - Fault Immediately After Shift
When monitored: After a speed ratio error DTC is stored.
Set condition: This DTC is set if the associated speed ratio DTC is stored within 1.3 seconds after a shift.
Theory of operation: This DTC will only be stored along with a 50 series DTC. If this DTC is set, it indicates the problem is possibly mechanical in nature. When this DTC exists, diagnosing the transmission should be based on the associated speed ratio DTC and mechanical causes should be considered first.
Transmission Effects: None
Possible causes:
^ Mechanical causes as listed under associated speed ratio DTC

Name of DTC: P-1775(37) - Solenoid Switch Valve Latched in TCC Position
When monitored: During an attempted shift into 1st gear.
Set condition: This DTC is set if three unsuccessful attempts are made to get into 1st gear in one given ignition start.
Theory of operation: 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 the fluid to the L-R clutch circuit. In 2nd, 3rd, and 4th, it will be in the upshift 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), 2nd gear is substituted for 1st.
Transmission Effects: Transmission will have no 1st gear (2nd gear will be substituted), and no EMCC operation. The MIL will illuminate after 5 minutes of substituted gear operation.
Possible causes:
^ PRNDL indicates a valid OD DTC in the hydraulic reverse position
^ Valve body - Solenoid Switch Valve stuck in TCC position
^ High idle speed
^ Solenoid malfunction - may also set DTC P-1784(81)
^ L-R Pressure Switch Sense circuit shorted to battery

Name of DTC: P-0740(38) - Torque Converter Clutch Control Circuit
When monitored: During Electronically Modulated Converter Clutch (EMCC) Operation.
Set condition:
a The transmission must be in EMCC, with the input speed greater than 1750 RPM. The TCC/L-R solenoid must achieve the maximum duty cycle and still not be able to pull the engine speed within 60 RPM of input speed.
b If the transmission is in FEMCC and the engine can slip the TCC by more than 100 RPM (Engine speed-Input speed) for 10 seconds.
The DTC will be set if one of these events happens three times at a throttle angle less than 30 degrees.
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 DTC 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:
^ Worn pump bushing and/or failed torque converter - both should be replaced during a rebuild with DTC 38 present
^ Sticky CC Regulator valve

Name of DTC: P-1776(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 DTC 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 L-R 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. A second detection of L-R pressure results in setting the DTC.
Transmission Effects: EMCC is inhibited and the transmission system will default to the Orderly Shutdown routine.
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 DTC P-1784 only)
^ Solenoid/TRS assembly (with DTC P-1784(81) only)
^ TCM (with DTC P-1784(81) only)

Name of DTC: P-1793(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 DTC 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 TCMs 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. Consequently, a customer may complain about loss of performance or of short shifting when driving aggressively.
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 DTC:
P-0736(50) - Speed Ratio Error in Reverse
P-0731(51) - Speed Ratio Error in 1st
P-0732(52) - Speed Ratio Error in 2nd
P-0733(53) - Speed Ratio Error in 3rd
P-0734(54) - Speed Ratio Error in 4th
P-1736(55) - Speed Ratio Error in 2nd Prime
P-0715(56) - Input Speed Sensor
P-0720(57) - Output Speed Sensor
P-1794(58) - Speed Sensor Ground
When monitored: The transmission gear ratio is monitored continuously while the transmission is in gear.
Set condition: This DTC is set if the gear ratio is not correct for the current gear.
- DTCs 50 through 55 sets if the ratio of the input RPM (Nt) to the output RPM (No) does not match the current gear ratio
- DTC 56 sets if there is an excessive change in input RPM in any gear
- DTC 57 sets if there is an excessive change in output RPM in any gear
- DTC 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. There-fore, 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 DTC is set (DTCs 50 through 55).
2 An excessive change in input or output speeds indicating signal will result in DTCs 56 and/or 57 being set.
3 If the common speed sensor ground circuit is lost, both sensor inputs will read the output 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 DTC is set as a one trip failure and the 5 minute Intelligent Recovery Timer (IRT) is started. The transmission will then substitute a different gear for the one in which the problem was identified. For example, if a problem is identified while in second 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 and the transmission system will default to the Logical Shutdown with Full Recovery (R) routine after 5 minutes of substituted gear operation or if three gear ratio error events occur in a given key start.
Possible causes: DTC P-0736(50) - Excludes geartrain failures which should be obvious upon disassembly
> If DTC P-1791(35) or any line pressure DTC is set, diagnose those first
> Valve body - #3 ball check
> L-R switch valve sticking - may also set DTC P-0731(51)
> Speed sensor or associated wiring - may also set DTCs P-0731(51), P-0715(56), or P-0720(57)
> Multi Select Solenoid sticking or leaking
> Failed or slipping L-R clutch - may also set DTC P-0731(51)
- L-R seal leakage (Intermittent no drive or reverse)
- Sticky L-R accumulator seals (Intermittent no drive or reverse)
> Failed reverse clutch (hard DTC)
- OD/Rev lip seal leakage
- Worn reaction shaft support seal rings
DTC P-0731(51) - Excludes geartrain failures which should be obvious upon disassembly
> If DTC P-1791(35) or any line pressure DTCs are set, diagnose those first
> Valve body - #1, #2, and/or #4 ball check
> L-R switch valve sticking
> Speed sensor or associated wiring - may also set DTCs P-0736(50), P-0715(56), or P-0720(57)
> Solenoid/TRS assembly (stuck solenoid(s))
> Failed or intermittent slipping UD clutch - may also set DTCs P-0732(52) or P-0733(53)
- UD seal leakage
- Sticky UD accumulator seals
- Worn reaction shaft support seal rings
> Failed or slipping L-R clutch - may have DTC P-0736(50)
- L-R seal leakage
- Sticky L-R accumulator seals
DTC P-0732(52) - Excludes geartrain failures which should be obvious upon disassembly
> If DTC P-1791(35) or any line pressure DTC are set, diagnose those first
> Valve body - #1, #2, #4, #5 and/or #7 ball check
> Solenoid/TRS assembly - may also set DTCs P-1734(54) and/or P-1728(A2) Failed or slipping 2nd clutch
- 2nd clutch seal leakage
- Sticky 2nd clutch accumulator seals
> Failed or intermittent slipping UD clutch - may also set DTC P-0731(51) and/or P-0733(53)
- UD clutch seal leakage
- Worn input hub bushing
- Sticky UD clutch accumulator seals
- Worn reaction shaft support seal rings
DTC P-0733(53) - Excludes geartrain failures which should be obvious upon disassembly
> If DTC P-1791(35) or any line pressure DTC are set, diagnose those first
> Valve body - #1, #2, and/or #6 ball check
> Speed sensor or associated wiring - may also set DTCs P-0736(50), P-0715(56), or P-0720(57)
> Solenoid/TRS assembly - may also set DTCs P-1781(84) and/or P-1787(A4)
> Failed or slipping OD clutch - may also set DTC P-0734(54)
- OD clutch inner and outer lip seal leakage
- Sticky OD clutch accumulator seals
- Worn reaction shaft support seal rings
> Failed or intermittent slipping UD clutch may also set DTCs P-0731(61) and/or P-0732(52)
- UD seal leakage
- Worn input hub bushing
- Sticky UD clutch accumulator seals
- Worn reaction shaft support seal rings
DTC P-0734(54) - Excludes geartrain failures which should be obvious upon disassembly
> If DTC P-1791(35) or any line pressure DTCs are set, diagnose those first
> Valve body - #1, #2, #5 and/or #6 ball check
> Speed sensor or associated wiring - may also set DTCs P-0736(50), P-0715(56), or P-0720(57)
> Solenoid/TRS assembly - may also set DTCs P-1733(88) and/or P-1727(A8)
> Failed or slipping OD clutch - may also set DTC P-0733(53)
- OD clutch inner and outer lip seal leakage
- Sticky OD clutch accumulator seals
- Worn reaction shaft support seal rings
> Failed or intermittent slipping 4th clutch
- 4th clutch seal leakage
- Sticky 4th clutch accumulator seals
- Worn reaction shaft support seal rings
DTC P-1736(55) - Excludes geartrain failures which should be obvious upon disassembly
> If DTC P-1791(35) or any line pressure DTC are set, diagnose those first
> Valve body - #1, #4 and for #5 ball check
> Speed sensor or associated wiring - may also set DTCs P-0736(50), P-0715(56), or P-0720(57)
> Solenoid/TRS assembly - may also set DTCs P-1732(90) and for P-1726(B0)
> Failed or intermittent slipping UD clutch - may also set DTCs P-0731(51) and/or P-0732(52)
- UD seal leakage
- Worn input hub bushing
- Sticky UD clutch accumulator seals
- Worn reaction shaft support seal rings
> Failed or intermittent slipping 4th clutch
- 4th clutch seal leakage
- Sticky 4th clutch accumulator seals
- Worn reaction shaft support seal rings
DTCs P-0715(56) and P-0720(57)
> Failed input or output speed sensor
> Shorted or open wiring between TCM and speed sensor(s)
> Connector problems at 60-way TCM connector and/or speed sensor connector(s) DTC P-1794(58)
> Open or shorted speed sensor ground (speed sensor ground is different from chassis ground)
> Open or shorted Temperature Sensor wiring to TRS
> TRS - Will also set DTC P-1799(74)
> TCM

Name of DTC: P-1715(65)Restricted Port in T3 Range
When Monitored: Whenever the Engine is running and the Manual valve is in the T3 range.
Set condition: The DTC is set if the conditions for a DTC 47 are present when the manual valve is in the T3 range.
Theory of Operation: The conditions to set a DTC P-1776(47) are easily satisfied while in the T3 range. There is no problem with the transmission itself if this DTC is set.
Transmission Effects: The transmission will go into neutral when this DTC is set. If the driver puts the shifter in neutral and back to drive, the transmission will operate normally.
Possible Causes:
> Manual linkage out of adjustment, causing T3 range while shifter is in OD
> Driver resting hand on shift lever while driving, causing T3 range