Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC B2853: Telescope Forward Switch Circuit HighDTC B2858: Telescope Rearward Switch Circuit High
DTC B2873: Tilt Up Switch Circuit High
DTC B2878: Tilt Down Switch Circuit High
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Tilt/Telescope Switch Battery Positive Voltage | 1* | 1 | -- | -- |
Steering Column Telescope Forward Switch Signal | 1* | 2 | B2853 | -- |
Steering Column Telescope Reverse Switch Signal | 1* | 3 | B2858 | -- |
Steering Column Tilt Down Switch Signal | 1* | 4 | B2878 | -- |
Steering Column Tilt Up Switch Signal | 1* | 5 | B2873 | -- |
* Open HUD Fuse
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Circuit/System Description
The instrument panel module (IPM) receives voltage inputs from contacts inside the tilt/telescope switch. The IPM sends the tilt/telescope switch information to the memory seat module (MSM) via the low speed GMLAN serial data circuit. The MSM then supplies battery voltage to the tilt motor up or down circuit, or the telescope motor in or out circuit depending on which direction of movement is requested. Both motors are reversible and voltage is applied to either circuit to accomplish movement in opposite directions. The MSM monitors the position and movement of the tilt and telescoping actuators on the sensor signal circuits.
Conditions for Running the DTC
Ignition ON
Conditions for Setting the DTC
The MSM detects a switch input for more than 30 consecutive seconds after movement of the motor in the requested direction has stopped.
Action Taken When the DTC Sets
| • | The motor that is being driven by the failed switch will be deactivated. |
| • | Memory recall functions will be disabled. |
Conditions for Clearing the DTC
| • | A current DTC will clear when the failed switch input is no longer active. |
| • | A history DTC will clear after 100 ignition cycles. |
Diagnostic Aids
An intermittently stuck switch can cause this DTC to set. Also, the driver can cause this DTC to set by holding the switch for 30 seconds after the column reaches the end of its travel.
Reference Information:
Schematic Reference:
Tilt/Telescoping Steering Column Schematics
Connector End View Reference:
Steering Wheel and Column Connector End Views
Description and Operation:
Steering Wheel and Column Description and Operation
Electrical Information Reference:
Scan Tool Reference:
Circuit/System Verification
Ignition ON, observe the folllowing parameters in the Instrument Panel Module Data Display of the scan tool:
| • | Tilt Up Switch |
| • | Tilt Down Switch |
| • | Telescope Forward Switch |
| • | Telescope Rearward Switch |
The scan tool should display Inactive for all 4 parameters when the switch is not pressed, and Active for any switch that is pressed.
Circuit/System Testing
- Ignition OFF, disconnect the C2 harness connector at the IPM.
- Ignition OFF, test for less than 1 volt on each of the switch signal circuits terminals 13, 14, 21, and 22.
- If all circuits test normal, test or replace the IPM.
| ⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the switch. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for IPM replacement, setup, and programming |
