2010 Cadillac CTS Sedan AWD V6-3.0L Page 1672
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.
DTC Descriptors
DTC P0815
- Upshift Switch 1 Circuit
DTC P0816
- Downshift Switch 1 Circuit
DTC P0826
- Up and Down Shift Switch 1 Circuit
DTC P1876
- Up and Down Shift Enable Switch Circuit Low Voltage
Diagnostic Fault Information
Circuit/System Description
The drivers shift control (DSC) also known as the Tap UP/Down feature allows the driver to shift or change gears similar to a manual transmission.
Activating the DSC is accomplished by placing the shift lever in the manual (M) mode position. To place the shift lever in M position, move the
shift lever to the right from the drive (D) position gate. When the shift lever is in the M position an upshift is accomplished pushing the shift lever
forward. A downshift is accomplished by pulling back or pushing rearward on the shift lever. A redundant set of Tap UP/Down switches are
available on the steering wheel horizontal crossbar facing the instrument panel. The plus (+) switch is located on the right side of the steering wheel
and the minus (-) switch is located on the left side of the steering wheel. A 12 volt parallel circuit from the body control module (BCM) supplies
voltage to the automatic transmission manual shift switch on the shift lever and to the automatic transmission manual shift switches on the steering
wheel. A separate signal circuit from each switch to the BCM provides the information on each Tap Up/Down command. The BCM sends the
requested command on the serial data line to the transmission control module (TCM) to perform the shift.
Conditions for Running the DTC
P0815 or P0816
* No DTC P0826.
* No DTCs P1825 or P1915.
* The engine speed is between 500-7,500 RPM for at least 5 seconds.
* The time since the last gear selector range change is greater than 6 seconds.
P0826
* Ignition voltage is 8.6-19.0 volts.
* Engine speed is 500-6,500 RPM for at least 5 seconds.
P1876
* The following DTCs are not Fault Active or Test Fail this Key ON:
- DTC U0100.
- DTCs P0815, P0816, or P0826.
- DTCs P1825 or P1915.
* Ignition voltage is 8.6-19.0 volts.
* Engine speed is 500-6,500 RPM for at least 5 seconds.
Conditions for Setting the DTC
P0815
The TCM detects a Stuck ON upshift switch for 3 seconds in PARK, REVERSE, NEUTRAL, or D and for 600 seconds in PARK, REVERSE,
