Do I have another faulty PCM? - JeepForum.com
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post #1 of 43 Old 11-29-2018, 07:35 PM Thread Starter
rcroane
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Do I have another faulty PCM? - Resolved (I think!)

Here's the background and my current situation....

My '06 TJ auto trans had the classic hard shift problem caused by a faulty PCM. I replaced it with a Chrysler remanufactured PCM. Shifts were buttery smooth for the first 300 miles. Since then, I have two issues. When I start out in the morning, the first shift into second gear takes awhile (about 2200 RPM's), but the shift itself is pretty smooth. As the engine warms up, things get smoother and smoother. So, I'm happy with that part because with my old PCM, the first couple of shifts when starting out cold were very hard.

Now, here's the issue. If I run an errand and stop in a store for 10-15 minutes, when I start the Jeep again and take off, the first shift is hard. The Jeep had completely warmed up before I stopped for the errand, and was still showing about 125 degrees on my temp gauge when I took off after the errand. This isn't a one time thing....happens every time. I've even tried sitting with the Jeep idling until it reaches full operating temp...still jerks on that first shift.

Disconnecting the battery puts everything back to buttery smooth every time for about 300 miles.

Sound like a bad PCM? Glad this one is under warranty.


Thanks.

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post #2 of 43 Old 11-29-2018, 09:48 PM
ZachRS
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Just a little background here, I work at a transmission shop and deal with similar issues on a daily basis.
Sounds to me like a trans issue.
The only thing that’s happening by disconnecting the pcm is forcing the trans to relearn its shift adapts. The first 300 miles the trans is more than likely actually slipping into 2nd. Once the pcm has recognized this, it jacks line pressure in order to compensate giving you the harsh shift feeling. If I were you I’d drop the trans pan and check the band adjustment, there should be about 1/4” of travel pulling down.
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post #3 of 43 Old 11-29-2018, 09:54 PM
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Quote:
Originally Posted by rcroane View Post
Here's the background and my current situation....

My '06 TJ auto trans had the classic hard shift problem caused by a faulty PCM. I replaced it with a Chrysler remanufactured PCM. Shifts were buttery smooth for the first 300 miles. Since then, I have two issues. When I start out in the morning, the first shift into second gear takes awhile (about 2200 RPM's), but the shift itself is pretty smooth. As the engine warms up, things get smoother and smoother. So, I'm happy with that part because with my old PCM, the first couple of shifts when starting out cold were very hard.

Now, here's the issue. If I run an errand and stop in a store for 10-15 minutes, when I start the Jeep again and take off, the first shift is hard. The Jeep had completely warmed up before I stopped for the errand, and was still showing about 125 degrees on my temp gauge when I took off after the errand. This isn't a one time thing....happens every time. I've even tried sitting with the Jeep idling until it reaches full operating temp...still jerks on that first shift.

Disconnecting the battery puts everything back to buttery smooth every time for about 300 miles.

Sound like a bad PCM? Glad this one is under warranty.


Thanks.
May be under warranty but they dont service that part anymore. Its NS1. Theyre done with it. I got 2 bad ones. They cancelled the third. Theyre giving me my money back.
Im putting a L83 and 6L80 in. No more Chrysler crap electronics.
355 Hp and a good transmission. That 42RLE is terrible.
I didnt want to V8 mine yet but waited all this year for a solution and it was sorry were done.
Good luck with youre Jeep. Theres getting to be a lot of 05/06 owners with PCM issues.
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post #4 of 43 Old 11-30-2018, 06:16 AM
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Quote:
Originally Posted by ZachRS View Post
Just a little background here, I work at a transmission shop and deal with similar issues on a daily basis.
Sounds to me like a trans issue.
The only thing thats happening by disconnecting the pcm is forcing the trans to relearn its shift adapts. The first 300 miles the trans is more than likely actually slipping into 2nd. Once the pcm has recognized this, it jacks line pressure in order to compensate giving you the harsh shift feeling. If I were you Id drop the trans pan and check the band adjustment, there should be about 1/4 of travel pulling down.
Are there band adjustments on the 42RLE?
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post #5 of 43 Old 11-30-2018, 07:16 AM
Alaska-HWY JK
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Quote:
Originally Posted by biffgnar View Post
Are there band adjustments on the 42RLE?
My reading says 42RE has bands, 42RLE no adjustments.
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post #6 of 43 Old 11-30-2018, 07:46 AM
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Quote:
Originally Posted by Alaska-HWY JK View Post
42RLE no adjustments.
That has always been my understanding.
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post #7 of 43 Old 11-30-2018, 07:47 AM Thread Starter
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Quote:
Originally Posted by Alaska-HWY JK View Post
My reading says 42RE has bands, 42RLE no adjustments.
Well crap then....sounds like I got a bad Chrysler PCM.
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post #8 of 43 Old 11-30-2018, 07:55 AM
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Quote:
Originally Posted by rcroane View Post
Quote:
Originally Posted by Alaska-HWY JK View Post
My reading says 42RE has bands, 42RLE no adjustments.
Well crap then....sounds like I got a bad Chrysler PCM.
My bad- did not see the 2006 part, was thinking older with a 32rh.
And I would still check the trans before condemning the pcm.
42rle do have solenoid pack issues and are quite common. I’ve also had 42rle with oddball shift issues that a service and flush has helped with.
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post #9 of 43 Old 11-30-2018, 11:18 AM Thread Starter
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Quote:
Originally Posted by ZachRS View Post
My bad- did not see the 2006 part, was thinking older with a 32rh.
And I would still check the trans before condemning the pcm.
42rle do have solenoid pack issues and are quite common. Ive also had 42rle with oddball shift issues that a service and flush has helped with.
Thanks. I'll have the trans checked out. I recently did a full fluid flush. First time for me...hope I didn't screw something up.
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post #10 of 43 Old 11-30-2018, 06:51 PM
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A bit of a long post, but good reading to understand the 42RLE shift control better. From the FSM:

The TCM is the controlling unit for all electronic operations of the transmission. The TCM receives information regarding vehicle operation from both direct and indirect inputs, and selects the operational mode of the transmission. Direct inputs are hardwired to, and used specifically by the TCM. Indirect inputs originate from other components/modules, and are shared with the TCM via the PCI bus. Some examples of direct inputs to the TCM are:
Battery (B+) voltage
Ignition ON voltage
Transmission Control Relay (Switched B+)
Throttle Position Sensor
Crankshaft Position Sensor (CKP)
Transmission Range Sensor (TRS)
Pressure Switches (L/R, 2/4, OD)
Transmission Temperature Sensor (Integral to TRS)
Input Shaft Speed Sensor
Output Shaft Speed Sensor
Some examples of indirect inputs to the TCM are:
Engine/Body Identification
Manifold Pressure
Target Idle
Torque Reduction Confirmation
Speed Control ON/OFF Switch
Engine Coolant Temperature
Ambient/Battery Temperature
Brake Switch Status
DRBt III Communication
Based on the information received from these various inputs, the TCM determines the appropriate shift schedule and shift points, depending on the present operating conditions and driver demand. This is possible through the control of various direct and indirect outputs. Some examples of TCM direct outputs are:
Transmission Control Relay
Solenoids (L/R, 2/4, OD and UD)
Vehicle Speed (to PCM)
Torque Reduction Request (to PCM)
Some examples of TCM indirect outputs are:
Transmission Temperature (to PCM)
PRNDL Position (to BCM)
In addition to monitoring inputs and controlling outputs, the TCM has other important responsibilities and functions:
Storing and maintaining Clutch Volume Indices (CVI)
Storing and selecting appropriate Shift Schedules
System self-diagnostics
Diagnostic capabilities (with DRBt III scan tool)

CLUTCH VOLUME INDEX (CVI)
An important function of the TCM is to monitor Clutch Volume Index (CVI). CVIs represent the volume of fluid needed to compress a clutch pack. The TCM monitors gear ratio changes by monitoring the Input and Output Speed Sensors. The Input, or Turbine Speed Sensor sends an electrical signal to the TCM that represents input shaft rpm. The Output Speed Sensor provides the TCM with output shaft speed information. By comparing the two inputs, the TCM can determine transmission gear position. This is important to the CVI calculation because the TCM determines CVIs by monitoring how long it takes for a gear change to occur (Fig. 14). Gear ratios can be determined by using the DRBt III Scan Tool and reading the Input/Output Speed Sensor values in the Monitors display. Gear ratio can be obtained by dividing the Input Speed Sensor value by the Output Speed Sensor value. For example, if the input shaft is rotating at 1000 rpm and the output shaft is rotating at 500 rpm, then the TCM can determine that the gear ratio is 2:1. In direct drive (3rd gear), the gear ratio changes to 1:1. The gear ratio changes as clutches are applied and released. By monitoring the length of time it takes for the gear ratio to change following a shift request, the TCM can determine the volume of fluid used to apply or release a friction element. The volume of transmission fluid needed to apply the friction elements are continuously updated for adaptive controls. As friction material wears, the volume of fluid need to apply the element increases. Certain mechanical problems within the input clutch assembly (broken return springs, out of position snap rings, excessive clutch pack clearance, improper assembly, etc.) can cause inadequate or out-of-range element volumes. Also, defective Input/Output Speed Sensors and wiring can cause these conditions.

SHIFT SCHEDULES
As mentioned earlier, the TCM has programming that allows it to select a variety of shift schedules. Shift schedule selection is dependent on the following:
Shift lever position
Throttle position
Engine load
Fluid temperature
Software level
As driving conditions change, the TCM appropriately adjusts the shift schedule.

TRANSMISSION OPERATION AND SHIFT SCHEDULING AT VARIOUS OIL TEMPERATURES
The transmission covered in this manual has unique shift schedules depending on the temperature of the transmission oil. The shift schedule is modified to extend the life of the transmission while operating under extreme conditions. The oil temperature is measured with a Temperature Sensor on the 42RLE transmission. The Temperature Sensor is an integral component of the Transmission Range Sensor (TRS). If the Temperature Sensor is faulty, the transmission will default to a calculated oil temperature. Oil temperature will then be calculated through a complex heat transfer equation using engine coolant temperature, battery/ambient temperature, and engine off time from the Body Control Module (BCM). These inputs are received from the PCI bus periodically and used to initialize the oil temperature at start up. Once the engine is started, the PCM updates the transmission oil temperature based on torque converter slip speed, vehicle speed, gear, and engine coolant temperature to determine an estimated oil temperature during vehicle operation. Vehicles using calculated oil temperature track oil temperature reasonably accurate during normal operation. However, if a transmission is overfilled, a transmission oil cooler becomes restricted, or if a customer drives aggressively in low gear, the calculated oil temperature will be inaccurate. Consequently the shift schedule selected may be inappropriate for the current conditions. The key highlights of the various shift schedules are as follows:
Extreme Cold: Oil temperature at start up below 26.6C (-16 F)
> Goes to Cold schedule above -24C (-12F) oil temperature
> Park, Reverse, Neutral and 2nd gear only (prevents shifting which may fail a clutch with frequent shifts)
Cold: Oil temperature at start up above -24C (-12F) and below 2.2C (36F)
> Goes to Warm schedule above 4.4C (40F) oil temperature
> Delayed 2-3 upshift approximately 35-50 Km/h (22 - 31 MPH)
> Delayed 3-4 upshift 72-85 Km/h (45-53 MPH)
> Early 4-3 coastdown shift approximately 48 Km/h (30 MPH)
> Early 3-2 coastdown shift approximately 27 Km/h (17 MPH)
> High speed 4-2, 3-2, 2-1 kickdown shifts are prevented
> No EMCC
Warm: Oil temperature at start up above 2.2C (36F) and below 27C (80F)
> Goes to a Hot schedule above 27C (80F) oil temperature
> Normal operation (upshifts, kickdowns, and coastdowns)
> No EMCC
Hot: Oil temperature at start up above 27C (80F)
> Goes to a Overheat schedule above 115C (240F) oil temperature
> Normal operation (upshifts, kickdowns, and coastdowns)
> Full EMCC, No PEMCC except to engage FEMCC, except at closed throttle at speeds above 113-133 Km/h (70 - 83 MPH)
Overheat: Oil temperature above 115C (240 F) or engine coolant temperature above 118C (244F)
> Goes to a Hot below 110C (230F) oil temperature or a Super Overheat above 115C (240F) oil temperature
> Delayed 2-3 upshift 40-51 Km/h (25-32 MPH)
> Delayed 3-4 upshift 66-77 Km/h (41-48 MPH)
> 3rd gear FEMCC from 48-77 Km/h (30-48 MPH)
> 3rd gear PEMCC from 43-50 Km/h (27-31 MPH
Super Overheat: Oil temperature above 127C (260F)
> Goes back to a Overheat below 115C (240F) oil temperature
> All a Overheat shift schedules features apply
> 2nd gear PEMCC above 35 Km/h (22 MPH)
> Above 35 Km/h (22 MPH) the torque converter will not unlock unless the throttle is closed (i.e. at 80 Km/h (50 MPH) a 4th FEMCC to 3rd FEMCC shift will be made during a part throttle kickdown or a 4th FEMCC to 2nd PEMCC shift will be made at wide open throttle) or if a wide open throttle 2nd PEMCC to 1 kickdown is made.
Causes for operation in the wrong temperature shift schedule: Extreme Cold or Cold shift schedule at start up:
> Temperature Sensor circuit.
> Overheat or Super Overheat shift schedule after extended operation:
> Operation in city traffic or stop and go traffic
> Engine idle speed too high
> Aggressive driving in low gear
> Trailer towing in OD gear position (use 3 position (or A/S 3rd) if frequent shifting occurs)
> Cooling system failure causing engine to operate over 110C (230F)
> Engine coolant temperature stays low too long If engine coolant temperature drops below 65C (150F), the transmission will disengage EMCC. Extended operation with the EMCC disengaged will cause the transmission to overheat.
> Brake switch issue will cause the EMCC to disengage. Extended operation with the EMCC disengaged will cause the transmission to overheat.
> Transmission fluid overfilled
> Transmission cooler or cooler lines restricted
> Transmission Temperature Sensor circuit

In short, there are numerous other possible causes of 42RLE shifting issues than just the PCM/TCM.

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post #11 of 43 Old 12-01-2018, 02:52 PM Thread Starter
rcroane
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Quote:
Originally Posted by mukluk View Post
A bit of a long post, but good reading to understand the 42RLE shift control better. From the FSM:

The TCM is the controlling unit for all electronic operations of the transmission. The TCM receives information regarding vehicle operation from both direct and indirect inputs, and selects the operational mode of the transmission. Direct inputs are hardwired to, and used specifically by the TCM. Indirect inputs originate from other components/modules, and are shared with the TCM via the PCI bus. Some examples of direct inputs to the TCM are:
Battery (B+) voltage
Ignition ON voltage
Transmission Control Relay (Switched B+)
Throttle Position Sensor
Crankshaft Position Sensor (CKP)
Transmission Range Sensor (TRS)
Pressure Switches (L/R, 2/4, OD)
Transmission Temperature Sensor (Integral to TRS)
Input Shaft Speed Sensor
Output Shaft Speed Sensor
Some examples of indirect inputs to the TCM are:
Engine/Body Identification
Manifold Pressure
Target Idle
Torque Reduction Confirmation
Speed Control ON/OFF Switch
Engine Coolant Temperature
Ambient/Battery Temperature
Brake Switch Status
DRBt III Communication
Based on the information received from these various inputs, the TCM determines the appropriate shift schedule and shift points, depending on the present operating conditions and driver demand. This is possible through the control of various direct and indirect outputs. Some examples of TCM direct outputs are:
Transmission Control Relay
Solenoids (L/R, 2/4, OD and UD)
Vehicle Speed (to PCM)
Torque Reduction Request (to PCM)
Some examples of TCM indirect outputs are:
Transmission Temperature (to PCM)
PRNDL Position (to BCM)
In addition to monitoring inputs and controlling outputs, the TCM has other important responsibilities and functions:
Storing and maintaining Clutch Volume Indices (CVI)
Storing and selecting appropriate Shift Schedules
System self-diagnostics
Diagnostic capabilities (with DRBt III scan tool)

CLUTCH VOLUME INDEX (CVI)
An important function of the TCM is to monitor Clutch Volume Index (CVI). CVIs represent the volume of fluid needed to compress a clutch pack. The TCM monitors gear ratio changes by monitoring the Input and Output Speed Sensors. The Input, or Turbine Speed Sensor sends an electrical signal to the TCM that represents input shaft rpm. The Output Speed Sensor provides the TCM with output shaft speed information. By comparing the two inputs, the TCM can determine transmission gear position. This is important to the CVI calculation because the TCM determines CVIs by monitoring how long it takes for a gear change to occur (Fig. 14). Gear ratios can be determined by using the DRBt III Scan Tool and reading the Input/Output Speed Sensor values in the Monitors display. Gear ratio can be obtained by dividing the Input Speed Sensor value by the Output Speed Sensor value. For example, if the input shaft is rotating at 1000 rpm and the output shaft is rotating at 500 rpm, then the TCM can determine that the gear ratio is 2:1. In direct drive (3rd gear), the gear ratio changes to 1:1. The gear ratio changes as clutches are applied and released. By monitoring the length of time it takes for the gear ratio to change following a shift request, the TCM can determine the volume of fluid used to apply or release a friction element. The volume of transmission fluid needed to apply the friction elements are continuously updated for adaptive controls. As friction material wears, the volume of fluid need to apply the element increases. Certain mechanical problems within the input clutch assembly (broken return springs, out of position snap rings, excessive clutch pack clearance, improper assembly, etc.) can cause inadequate or out-of-range element volumes. Also, defective Input/Output Speed Sensors and wiring can cause these conditions.

SHIFT SCHEDULES
As mentioned earlier, the TCM has programming that allows it to select a variety of shift schedules. Shift schedule selection is dependent on the following:
Shift lever position
Throttle position
Engine load
Fluid temperature
Software level
As driving conditions change, the TCM appropriately adjusts the shift schedule.

TRANSMISSION OPERATION AND SHIFT SCHEDULING AT VARIOUS OIL TEMPERATURES
The transmission covered in this manual has unique shift schedules depending on the temperature of the transmission oil. The shift schedule is modified to extend the life of the transmission while operating under extreme conditions. The oil temperature is measured with a Temperature Sensor on the 42RLE transmission. The Temperature Sensor is an integral component of the Transmission Range Sensor (TRS). If the Temperature Sensor is faulty, the transmission will default to a calculated oil temperature. Oil temperature will then be calculated through a complex heat transfer equation using engine coolant temperature, battery/ambient temperature, and engine off time from the Body Control Module (BCM). These inputs are received from the PCI bus periodically and used to initialize the oil temperature at start up. Once the engine is started, the PCM updates the transmission oil temperature based on torque converter slip speed, vehicle speed, gear, and engine coolant temperature to determine an estimated oil temperature during vehicle operation. Vehicles using calculated oil temperature track oil temperature reasonably accurate during normal operation. However, if a transmission is overfilled, a transmission oil cooler becomes restricted, or if a customer drives aggressively in low gear, the calculated oil temperature will be inaccurate. Consequently the shift schedule selected may be inappropriate for the current conditions. The key highlights of the various shift schedules are as follows:
Extreme Cold: Oil temperature at start up below 26.6C (-16 F)
> Goes to Cold schedule above -24C (-12F) oil temperature
> Park, Reverse, Neutral and 2nd gear only (prevents shifting which may fail a clutch with frequent shifts)
Cold: Oil temperature at start up above -24C (-12F) and below 2.2C (36F)
> Goes to Warm schedule above 4.4C (40F) oil temperature
> Delayed 2-3 upshift approximately 35-50 Km/h (22 - 31 MPH)
> Delayed 3-4 upshift 72-85 Km/h (45-53 MPH)
> Early 4-3 coastdown shift approximately 48 Km/h (30 MPH)
> Early 3-2 coastdown shift approximately 27 Km/h (17 MPH)
> High speed 4-2, 3-2, 2-1 kickdown shifts are prevented
> No EMCC
Warm: Oil temperature at start up above 2.2C (36F) and below 27C (80F)
> Goes to a Hot schedule above 27C (80F) oil temperature
> Normal operation (upshifts, kickdowns, and coastdowns)
> No EMCC
Hot: Oil temperature at start up above 27C (80F)
> Goes to a Overheat schedule above 115C (240F) oil temperature
> Normal operation (upshifts, kickdowns, and coastdowns)
> Full EMCC, No PEMCC except to engage FEMCC, except at closed throttle at speeds above 113-133 Km/h (70 - 83 MPH)
Overheat: Oil temperature above 115C (240 F) or engine coolant temperature above 118C (244F)
> Goes to a Hot below 110C (230F) oil temperature or a Super Overheat above 115C (240F) oil temperature
> Delayed 2-3 upshift 40-51 Km/h (25-32 MPH)
> Delayed 3-4 upshift 66-77 Km/h (41-48 MPH)
> 3rd gear FEMCC from 48-77 Km/h (30-48 MPH)
> 3rd gear PEMCC from 43-50 Km/h (27-31 MPH
Super Overheat: Oil temperature above 127C (260F)
> Goes back to a Overheat below 115C (240F) oil temperature
> All a Overheat shift schedules features apply
> 2nd gear PEMCC above 35 Km/h (22 MPH)
> Above 35 Km/h (22 MPH) the torque converter will not unlock unless the throttle is closed (i.e. at 80 Km/h (50 MPH) a 4th FEMCC to 3rd FEMCC shift will be made during a part throttle kickdown or a 4th FEMCC to 2nd PEMCC shift will be made at wide open throttle) or if a wide open throttle 2nd PEMCC to 1 kickdown is made.
Causes for operation in the wrong temperature shift schedule: Extreme Cold or Cold shift schedule at start up:
> Temperature Sensor circuit.
> Overheat or Super Overheat shift schedule after extended operation:
> Operation in city traffic or stop and go traffic
> Engine idle speed too high
> Aggressive driving in low gear
> Trailer towing in OD gear position (use 3 position (or A/S 3rd) if frequent shifting occurs)
> Cooling system failure causing engine to operate over 110C (230F)
> Engine coolant temperature stays low too long If engine coolant temperature drops below 65C (150F), the transmission will disengage EMCC. Extended operation with the EMCC disengaged will cause the transmission to overheat.
> Brake switch issue will cause the EMCC to disengage. Extended operation with the EMCC disengaged will cause the transmission to overheat.
> Transmission fluid overfilled
> Transmission cooler or cooler lines restricted
> Transmission Temperature Sensor circuit

In short, there are numerous other possible causes of 42RLE shifting issues than just the PCM/TCM.
@mukluk ....thanks for this. Can you tell me where to locate the input and output speed sensors that you referenced in my other post?
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post #12 of 43 Old 12-01-2018, 03:01 PM
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Left side of the transmission.
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post #13 of 43 Old 12-01-2018, 03:08 PM
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Speed sensor operation from the FSM:

The Input Speed Sensor provides information on how fast the input shaft is rotating. As the teeth of the input clutch hub pass by the sensor coil, an AC voltage is generated and sent to the TCM. The TCM interprets this information as input shaft rpm. The Output Speed Sensor generates an AC signal in a similar fashion, though its coil is excited by rotation of the rear planetary carrier lugs. The TCM interprets this information as output shaft rpm. The TCM compares the input and output speed signals to determine the following:
• Transmission gear ratio
• Speed ratio error detection
• CVI calculation
The TCM also compares the input speed signal and the engine speed signal to determine the following:
• Torque converter clutch slippage
• Torque converter element speed ratio

Cleaning the speed sensor connectors or removing and cleaning the sensors themselves has helped others with shift quality issues. If you remove the sensors to clean them, be sure to reseal their mount bolt during install to prevent fluid leakage.

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post #14 of 43 Old 12-01-2018, 06:04 PM Thread Starter
rcroane
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Quote:
Originally Posted by mukluk View Post
Speed sensor operation from the FSM:

The Input Speed Sensor provides information on how fast the input shaft is rotating. As the teeth of the input clutch hub pass by the sensor coil, an AC voltage is generated and sent to the TCM. The TCM interprets this information as input shaft rpm. The Output Speed Sensor generates an AC signal in a similar fashion, though its coil is excited by rotation of the rear planetary carrier lugs. The TCM interprets this information as output shaft rpm. The TCM compares the input and output speed signals to determine the following:
Transmission gear ratio
Speed ratio error detection
CVI calculation
The TCM also compares the input speed signal and the engine speed signal to determine the following:
Torque converter clutch slippage
Torque converter element speed ratio

Cleaning the speed sensor connectors or removing and cleaning the sensors themselves has helped others with shift quality issues. If you remove the sensors to clean them, be sure to reseal their mount bolt during install to prevent fluid leakage.
Cleaned both sensor connections....no change. Ill try removing and cleaning the sensors next.
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post #15 of 43 Old 12-01-2018, 06:09 PM
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You'll likely need to clear the adaptive memory again after cleaning the sensors then wait to see if the hard shift issue comes back.

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