6T70/6T75 - Automatic Transmission
DTC P0815, P0816, or P0826
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC P0815
-
Upshift Switch Circuit
DTC P0816
-
Downshift Switch Circuit
DTC P0826
-
Up and Down Shift Switch Circuit
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
When the shift lever is placed in manual mode (M), electronic range select (ERS), which allows for the selection of the range of gears available, is activated. This is also known as the tap shift function. The ERS allows the vehicle operator to increase the highest range by pressing the plus (+) button or decrease the highest range by pressing the minus (-) button. The body control module (BCM) supplies a signal circuit to the shift controller. The shift controller has switches connected to a resistor array. A voltage drop occurs across the resistor network. When the plus or minus button is pushed, a corresponding voltage drop occurs across the resistor network. This voltage drop is monitored by the BCM. The BCM will send the request to the transmission control module (TCM) to increase or decrease the available gear ranges.
Conditions for Running the DTC
P0815 or P0816
* DTC P0815, P0816, P0826, P1761, P182E, P1876, P1877, or P1915 is not set.
* Time since the range change is 1 second or greater.
* Engine speed is 400 RPM or greater for 5 seconds.
* Ignition voltage is 8.6 volts or greater.
P0826
* Engine speed is 400 RPM or greater for 5 seconds.
* Ignition voltage is 8.6 volts or greater.
* DTC P0826 or P1761 is not set.
Conditions for Setting the DTC
P0815 - Condition 1
TCM detects an upshift request for 1 second in Park or Neutral.
P0815 - Condition 2
TCM detects an upshift request for 10 minutes in any forward range.
P0816 - Condition 1
TCM detects a downshift request for 1 second in Park or Neutral.
P0816 - Condition 2
TCM detects a downshift request for 10 minutes in any forward range.
P0826
TCM detects an invalid voltage on the Tap up/Tap down signal circuit for 1 minute.
Action Taken When the DTC Sets
* DTCs P0815, P0816, and P0826 are Type C DTCs.
* TCM inhibits Tap Up/Down function.
* TCM inhibits manual shifting of forward gears.
Conditions for Clearing the DTC
DTCs P0815, P0816, and P0826 are Type C DTCs.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics 6T70/6T75 - Automatic Transmission
Connector End View Reference
* Component Connector End Views Sunshade - Left Front
* Inline Harness Connector End Views X110
Description and Operation
Transmission General Description Transmission General Description
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Programming and Relearning for scan tool information
Circuit/System Verification
Warning:
Refer to Parking Brake and Drive Wheels Warning Parking Brake and Drive Wheels Warning in the preface section.
1. Ignition ON.
2. Verify with a scan tool the Driver Shift Control Mode parameter displays Inactive with the shift lever in the Park, Reverse, Neutral, and Drive positions, and Active in the M position.
• If the parameter does not display the correct values
Refer to Circuit System Testing below.
• If the parameter displays the correct value
3. Shift lever in the M position, verify the scan tool Driver Shift Request parameter changes from None to Upshift when the plus button is pressed, and from none to Downshift when the minus button is pressed.
• If the parameter does not display the correct values
Refer to Circuit/System Testing below.
• If the parameter displays the correct value
4. After performing the above steps, verify that the DTC does not reset by operating the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions you observe from the Freeze Frame/Failure Records data. If the vehicle passes the Circuit/System Verification procedure, then STOP. Do not perform the Circuit/System Testing or Component Testing as this may result in an unnecessary part replacement. Refer to Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections.
Circuit/System Testing
Note:
You must perform the Circuit/System Verification first.
1. Ignition OFF, disconnect the harness connector from the S3 transmission shift lever.
2. Test for less than 5 ohms between the shift lever harness connector terminal 2 and ground.
• If 5 ohms or greater
Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 5 ohms
3. Ignition ON.
4. Verify the scan tool Driver Shift Control Mode parameter displays inactive.
• If Driver Shift Control Parameter does not display Inactive
Test the signal circuit for a short to voltage or ground.
• If signal circuit has short to voltage or ground, repair the signal circuit wire.
• If signal circuit tests normal, replace the K9 body control module.
• If Driver Shift Control Parameter displays Inactive
5. Verify a test lamp illuminates between the S3 transmission shift lever harness connector ignition circuit terminal 1 and ground circuit terminal 2.
• If the test lamp does not illuminate
1. Ignition OFF.
2. Test for less than 2 ohms in the ignition circuit end to end.
• If 2 ohms or greater, repair the ignition circuit.
• If less than 2 ohms, replace the K9 body control module.
• If the test lamp illuminates
6. Test for 11-13 volts at the S3 transmission shift lever harness connector between signal circuit terminal 3 and ground.
• If not between 11-13 volts
1. Ignition OFF.
2. Test for less than 2 ohms in the signal circuit end to end,
• If 2 ohms or greater, repair the signal circuit.
• If less than 2 ohms, replace the K9 body control module.
• If between 11-13 volts
7. Ignition OFF, connect the S3 transmission shift lever harness connector, Ignition ON.
8. Test for 11-13 volts by back probing the transmission shift lever connector between terminal 3 and ground with the shift lever in Park, Reverse, Neutral, and Drive.
• If not between 11-13 volts
Replace the S3 transmission shift lever assembly.
• If between 11-13 volts
9. Test for 8.0-10.6 volts between S3 transmission shift lever connector terminal 3 and ground with the shift lever in the M position.
• If not between 8.0-10.6 volts
Replace the S3 transmission shift lever.
• If between 8.0-10.6 volts
10. Test for 5.1-7.3 volts between S3 transmission shift lever connector terminal 3 and ground with the shift lever in the M position with the tap down minus button depressed.
• If not between 5.1-7.3 volts
Replace the S3 transmission shift lever.
• If between 5.1-7.3 volts
11. Test for 2.0-4.6 volts between S3 transmission shift lever connector terminal 3 and ground with the shift lever in the M position with the tap up plus button depressed.
• If not between 2.0-4.6 volts
Replace the S3 transmission shift lever.
• If between 2.0-4.6 volts
12. Replace the K9 body control module.
Repair Instructions
Note:
* Perform the Reset Transmission Adapts Reset Transmission Adapts following all transmission related repairs.
* Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection Control Solenoid Valve and Transmission Control Module Assembly Inspection
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Control Module References Programming and Relearning for BCM or control solenoid valve assembly replacement, setup and programming
* Transmission Control Replacement Transmission Control Replacement