2010 Cadillac CTS Sedan AWD V6-3.6L Page 1705
3. Observe the scan tool TCM IMS parameter while slowly moving the gear shift lever from Park through all ranges. Verify the gear position
matches the scan tool parameter. Refer to Transmission Internal Mode Switch Logic (See: Specifications/Mechanical
Specifications/Automatic Transmission/Transaxle/System Specifications/Transmission Internal Mode Switch Logic).
瀚慖f not the specified value, refer to Shift Control Linkage Adjustment (All Wheel Drive) (See: Transmission and Drivetrain/Automatic
Transmission/Transaxle/Shift Linkage/Adjustments)Shift Control Linkage Adjustment (Rear Wheel Drive) (See: Transmission and
Drivetrain/Automatic Transmission/Transaxle/Shift Linkage/Adjustments).
4. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the
conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Ignition OFF, disconnect the T12 automatic transmission assembly X1 connector.
2. Install the DT-47825-10 - jumper harness to the X1 vehicle wire harness connector.
3. Ignition OFF, test for less than 5 ohms between terminal 5 at the DT-47825-10 - jumper harness and ground at the transmission case.
瀚慖f greater than the specified value, test the ground circuit for an open/high resistance.
4. Ignition ON, verify with a scan tool the Park/Neutral parameter displays In Gear.
瀚慖f the Park/Neutral parameter displays Park/Neutral, test the signal circuit for a short to ground. If the circuit tests normal, replace the K20
ECM.
5. Ignition ON, connect a 3A fused jumper wire between terminal 3 on the DT-47825-10 - jumper harness and ground at the transmission case.
Verify with a scan tool the Park/Neutral parameter displays Park/Neutral.
瀚慖f the Park/neutral parameter displays In Gear, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the
K20 ECM.
6. Ignition OFF, disconnect the DT-47825-10 - jumper harness from the X1 vehicle harness connector.
7. Connect the X1 vehicle harness connector to the Q8 control solenoid valve assembly.
8. Remove the transmission fluid pan. Refer to Automatic Transmission Fluid, Fluid Pan and/or Filter Replacement ().
9. Disconnect the B15 automatic transmission internal mode switch electrical connector from the K71 TCM.
10. Ignition ON, test for 11-13 volts between terminal F on the K71 TCM and ground at the transmission case.
瀚慖f not within the specified range, replace the Q8 control solenoid valve assembly.
11. If all circuits test normal, replace the B15 automatic transmission internal mode switch.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control solenoid valve assembly or ECM
replacement, setup, and programming.
Note: If the IMS switch has been replaced, inspect the valve body detent spring to be sure it is centered over the detent lever. This prevents
the detent spring from hitting the IMS switch.
* Manual Shift Shaft Position Switch Replacement (See: Powertrain Management/Computers and Control Systems/Sensors and Switches -
Computers and Control Systems/Transmission Position Sensor/Switch/Service and Repair/Manual Shift Shaft Position Switch Replacement)
for IMS replacement.
P0851
DTC P0850-P0852
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
