Part 1B
Name of DTC: P-1776(47) - Solenoid Switch Valve (SSV) Latched in L-R PositionWhen 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 on 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's 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. 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 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 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(51) 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/or #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/or 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