I have hopes that this information on the 5R55W will Help.
5R55S (RWD) Transmission – with ETC (has turbine speed sensor)
The 5R55S replaces the 5R55W transmission from 2002 MY. The diagnostics for the 5R55S and 5R55W are identical. The controls are slightly different for vehicles that use Electronic Throttle Control (ETC) versus vehicles that do not use ETC.
Transmission Inputs The Digital Transmission Range (DTR) sensor provides a single analog and three digital inputs to the PCM. The PCM decodes these inputs to determine the driver-selected gear position. This input device is checked for opens and invalid input patterns. (P0708, P0705)
Turbine Shaft Speed (TSS) and Output Shaft Speed (OSS) sensors are analog inputs that are checked for rationality.
If the engine rpm is above the torque converter stall speed and engine load is high, it can be inferred that the vehicle must be moving. If there is insufficient output from the TSS sensor, a malfunction is indicated (P0715). If there is insufficient output from the OSS sensor, a malfunction is indicated (P0720).
Transmission Outputs
Shift Solenoids
The Shift Solenoid (SSA, SSB, SSC, SSD) output circuits are checked for opens and shorts by the PCM by monitoring the status of a feedback circuit from the output driver (P0750 SSA, P0755 SSB, P0760 SSC, P0765 SSD).
These vehicle applications will utilize an inductive signature circuit to monitor the shift solenoids functionally. The ISIG circuit monitors the current signature of the shift solenoid as the solenoid is commanded on. A solenoid that functions properly will show a characteristic decrease in current as the solenoid starts to move. If the solenoid is malfunctioning, the current will not change (P1714 SSA, P1715 SSB, P1716 SSC, P1717 SSD).
The ISIG test runs in conjunction with the other transmission functional tests. The lack of communication between the ISIG chip and the PCM microprocessor is also monitored (P1636).
Electronic Pressure Control Outputs The VFS solenoids are variable force solenoids that control line pressure and gear selection in the transmission.
The VFS solenoids have a feedback circuit in the PCM that monitors VFS current. If the current indicates a short to ground (low pressure), engine torque may be reduced to prevent damage to the transmission. (P0962, P0966, P0970). The VFS solenoids are also checked for functionality by utilizing a rationality test that looks at gear ratios. If VFS/shift solenoid electrical faults and shift solenoid ISIG faults are not present, then actual ratios versus expected ratios are used to infer VFS failures. (P0745 PCA, P0775 PCB, P0795 PCC).
Torque Converter Clutch
The Torque Converter Clutch (TCC) output circuit is a duty-cycled output that is checked electrically for opens and shorts by the PCM by monitoring the status of a feedback circuit from the output driver (P0743). These vehicle applications will utilize an inductive signature circuit to monitor the torque converter clutch. The ISIG circuit monitors the current signature of the TCC solenoid as the solenoid is commanded on. A solenoid that functions properly will show a characteristic decrease in current as the solenoid starts to move. If the solenoid is malfunctioning, the current will not change (P1740). The ISIG test runs in conjunction with the other transmission functional tests. The lack of communication between the ISIG chip and the PCM microprocessor is also monitored (P1636).
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Direct One Way Clutch
The Direct One Way Clutch is checked for functionality by utilizing a rationality test that looks at transmission input torque relative to commanded throttle position while in 1st, 3rd, or 4th gear. If a direct one way clutch fault is present, then the transmission will not be able to carry torque at high throttle angles in 1st, 3rd, or 4th gears. (P1700)
On Board Diagnostic Executive
The On-Board Diagnostic (OBD) Executive is a portion of the PCM strategy that manages the sequencing and execution of all diagnostic tests. It is the "traffic cop" of the diagnostic system. Each test/monitor can be viewed as an individual task, which may or may not be able to run concurrently with other tasks. The Diagnostic Executive enables/disables OBD monitors in order to accomplish the following:
• Sequence the OBD monitors such that when a test runs, each input that it relies upon has already
been tested.
• Controls and co-ordinates the execution of the individual OBD system monitors: Catalyst, Misfire,
EGR, O2, Fuel, AIR, EVAP and, Comprehensive Component Monitor (CCM).
• Stores freeze frame and "similar condition" data
• Manages storage and erasure of Diagnostic Trouble Codes as well as MIL illumination
• Controls and co-ordinates the execution of the On-Demand tests: Key On Engine Off (KOEO), Key
On Engine Running (KOER), and the Output Test Mode (OTM).
• Performs transitions between various states of the diagnostic and powertrain control system to
minimize the effects on vehicle operation.
• Interfaces with the diagnostic test tools to provide diagnostic information (I/M readiness, various
J1979 test modes) and responds to special diagnostic requests (J1979 Mode 08 and 09).
The diagnostic also executive controls several overall, global OBD entry conditions.
• The Diagnostic Executive waits for 4 seconds after the PCM is powered before initiating any OBD
monitoring. For the 2001 MY and beyond, this delay has been eliminated to meet the "zero startup
delay" misfire monitoring requirements.
• The Diagnostic Executive suspends OBD monitoring when battery voltage falls below 11.0 volts.
• The Diagnostic Executive suspends monitoring of fuel-system related monitors (catalyst, misfire,
evap, O2, AIR and fuel system) when fuel level falls below 15%
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Exponentially Weighted Moving Average
Exponentially Weighted Moving Averaging is a well-documented statistical data processing technique that is used to reduce the variability on an incoming stream of data. Use of EWMA does not affect the mean of the data, however, it does affect the distribution of the data. Use of EWMA serves to “filter out” data points that exhibit excessive and unusual variability and could otherwise erroneously light the MIL.
The simplified mathematical equation for EWMA implemented in software is as follows:
New Average = [New data point * “filter constant”] + [( 1 - “filter constant” ) * Old Average]
This equation produces an exponential response to a step-change in the input data. The "Filter Constant" determines the time constant of the response. A large filter constant (i.e. 0.90 ) means that 90% of the new data point is averaged in with 10% of the old average. This produces a very fast response to a step change. Conversely, a small filter constant (i.e. 0.10 ) means that only 10% of the new data point is averaged in with 90% of the old average. This produces a slower response to a step change.
When EWMA is applied to a monitor, the new data point is the result from the latest monitor evaluation. A new average is calculated each time the monitor is evaluated and stored in Keep Alive Memory (KAM). This normally occurs each driving cycle. The MIL is illuminated and a DTC is stored based on the New Average store in KAM. In order to facilitate repair verification and DDV demonstration, 2 different filter constants are used.
A “fast filter constant” is used after KAM is cleared/DTCs are erased and a “normal filter constant” is used for normal customer driving. The “fast filter” is used for 2 driving cycles after KAM is cleared/DTCs are erased, and then the “normal filter” is used. The “fast filter” allows for easy repair verification and monitor demonstration in 2 driving cycles, while the normal filter is used to allow up to 6 driving cycles, on average, to properly identify a malfunction and illuminate the MIL.
In order to relate filter constants to driving cycles for MIL illumination, filter constants must be converted to time constants. The mathematical relationship is described below:
Time constant = [ ( 1 / filter constant ) - 1 ] * evaluation period
The evaluation period is a driving cycle. The time constant is the time it takes to achieve 68% of a step-change to an input. Two time constants achieve 95% of a step change input. Catalyst Monitor EWMA. EWMA has been incorporated in the catalyst monitor. There are 3 calibrate able parameters that determine the MIL illumination characteristics.
“Fast” filter constant, used for 2 driving cycles after DTCs are cleared or KAM is reset
“Normal” filter constant, used for all subsequent, “normal” customer driving Number of driving
cycles to use fast filter after KAM clear (normally set to 2 driving cycles)
Several examples for a typical calibration (4.6L Mark VIII ) are shown in the tables below. Specific calibration information can be obtained from the parameter listing provided for each strategy.
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Monitor evaluation (“new data”) EWMA Filter Calculation,“normal” filter constant set to 0.4
Malfunction threshold = .75
Weighted Average (“new average”)
Driving cycle number
Action/Comment
0.15 .15 * (0.4) + .15 * ( 1 - 0.4) 0.15 normal 100K system
1.0 1.0 * (0.4) + .15 * ( 1 - 0.4) 0.49 1 catastrophic failure
1.0 1.0 * (0.4) + .49 * ( 1 - 0.4) 0.69 2
1.0 1.0 * (0.4) + .69 * ( 1 - 0.4) 0.82 3 exceeds threshold
1.0 1.0 * (0.4) + .82 * ( 1 - 0.4) 0.89 4 MIL on
0.15 .15 * (0.4) + .15 * ( 1 - 0.4) 0.15 normal 100K system
0.8 0.8 * (0.4) + .15 * ( 1 - 0.4) 0.41 1 1.5 * threshold failure
0.8 0.8 * (0.4) + .41 * ( 1 - 0.4) 0.57 2
0.8 0.8 * (0.4) + .57 * ( 1 - 0.4) 0.66 3
0.8 0.8 * (0.4) + .66 * ( 1 - 0.4) 0.72 4
0.8 0.8 * (0.4) + .72 * ( 1 - 0.4) 0.75 5 exceeds threshold
0.8 0.8 * (0.4) + .75 * ( 1 - 0.4) 0.77 6 MIL on
I/M Readiness Code
The readiness function is implemented based on the J1979 format. A battery disconnection or clearing codes using a scan tool results in the various I/M readiness bits being set to a “not-ready” condition. As each noncontiguous monitor completes a full diagnostic check, the I/M readiness bit associated with that monitor is set to a “ready” condition. This may take one or two driving cycles based on whether malfunctions are detected or not.
The readiness bits for comprehensive component monitoring, misfire and fuel system monitoring are considered complete once all the non-continuous monitors have been evaluated. Because the evaporative system monitor requires ambient conditions between 40 and 100
o
F and BARO > 22.5 " Hg (< 8,000 ft.) to run, special logic can
“bypass” the running the evap monitor for purposes of clearing the evap system I/M readiness bit due to the
continued presence of these extreme conditions.
Evap bypass logic for 1997, 1998 and 1999 MY c/o vehicles:
If the evaporative system monitor cannot complete because ambient temperature conditions were encountered outside the 40 to 100 o F and BARO range at speeds above 40 mph during a driving cycle in which all continuous and non-continuous monitors were evaluated, the evaporative system monitor is then considered complete due to the continued presence of extreme conditions. If the above conditions are repeated during a second driving cycle, the I/M readiness bit for the evaporative system is set to a “ready” condition. (Note: Some 1997 and 1998 vehicles do not require catalyst monitor completion to bypass.)
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Evap bypass logic for new 1999 MY, 2000 MY, and beyond vehicles:
If the evaporative system monitor conditions are met with the exception of the 40 to 100 o F ambient temperatures or BARO range, a timer is incremented. The timer value is representative of conditions where the Evap monitor could have run (all entry conditions met except IAT and BARO) but did not run due to the presence of those extreme conditions. If the timer continuously exceeds 30 seconds during a driving cycle in which all continuous and non-continuous monitors were evaluated, the evaporative system monitor is then considered complete. If the above conditions are repeated during a second driving cycle, the I/M readiness bit for the evaporative system is set to a “ready” condition.
Power Take Off Mode
While PTO mode is engaged, the I/M readiness bits are set to a “not-ready” condition. When PTO mode is disengaged, the I/M readiness bits are restored to their previous states prior to PTO engagement. During PTO mode, only CCM circuit checks continue to be performed.
Catalyst Temperature Model:
A catalyst temperature model is currently used for entry into the catalyst and oxygen sensor monitors. The catalyst temperature model uses various PCM parameters to infer exhaust/catalyst temperature. For the 1998 MY, the catalyst temperature model has been enhanced and incorporated into the Type A misfire monitoring logic. The model has been enhanced to include a misfire-induced exothermic prediction. This allows the model to predict catalyst temperature in the presence of misfire.
The catalyst damage misfire logic (Type A) for MIL illumination has been modified to require that both the catalyst damage misfire rate and the catalyst damage temperature is being exceeded prior to MIL illumination. This change is intended to prevent the detection of unserviceable, unrepeatable, burst misfire during cold engine startup while ensuring that the MIL is properly illuminated for misfires that truly damage the catalyst.
Serial Data Link MIL Illumination
The instrument cluster on some vehicles uses the J1850 serial data link to receive and display various types of information from the PCM. For example, the engine coolant temperature information displayed on the instrument cluster comes from the same ECT sensor used by the PCM for all its internal calculations.
These same vehicles use the J1850 serial data link to illuminate the MIL rather than a circuit, hard-wired to the PCM. The PCM periodically sends the instrument cluster a message that tells it to turn on the MIL, turn off the MIL or blink the MIL. If the instrument cluster fails to receive a message within a 5-second timeout period, the instrument cluster itself illuminates the MIL. If communication is restored, the instrument cluster turns off the MIL after 5 seconds. Due to its limited capabilities, the instrument cluster does not generate or store Diagnostic Trouble Codes.
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