GM Service Manual Online
For 1990-2009 cars only

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 Descriptor

DTC B2870 01: Tilt Up Switch Circuit Short to Battery

DTC B2875 01: Tilt Down Switch Circuit Short to Battery

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Steering Wheel Column Tilt Switch B+

1

1

--

--

Steering Column Tilt Up Switch Signal

1

1

B2870 01

--

Steering Column Tilt Down Switch Signal

1

1

B2875 01

--

1. Tilt Malfunction

Circuit Description

The memory seat module (MSM) receives voltage inputs from the tilt switch based on the position of the switch. The MSM then supplies battery voltage and a ground to the tilt motor control circuits depending on which direction of movement is requested.

Conditions for Running the DTC

The ignition ON.

Conditions for Setting the DTC

The MSM detects a tilt switch input for more than 30 consecutive seconds after the tilt motor movement has stopped.

Action Taken When the DTC Sets

    • The tilt motor 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    • A current DTC will clear when the failed switch input is no longer active.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 tilt switch may cause a DTC to set.

Reference Information

Schematic Reference

Steering Wheel Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Steering Wheel and Column Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for Scan Tool Information

Circuit/System Verification

Ignition ON, view the appropriate scan tool Tilt Switch parameter while cycling the appropriate switch between states.The reading should change between Inactive and Active.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the tilt switch.
  2. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal B and ground.
  3. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  4. Verify the appropriate scan tool tilt switch parameter is Inactive.
  5. If not the specified value, test the appropriate control circuit for a short to voltage. If the circuit tests normal, replace the MSM.
  6. Install a 3A fused jumper wire between the B+ circuit terminal B and the control circuit terminals listed below. Verify the appropriate scan tool tilt switch parameter is Active.
  7. • Tilt Up Switch - control circuit terminal C
    • Tilt Down Switch - control circuit terminal A
    If not the specified value, test the appropriate control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.
  8. If all circuit test normal, test or replace the tilt switch.

Component Testing

Tilt Switch

  1. Ignition OFF, disconnect the harness connector at the tilt switch.
  2. Test for infinite resistance between control terminals A and C with the switch in the neutral position.
  3. If less than the specified range, replace the tilt switch.
  4. Test for less than 1 ohm between the B+ terminal B and the control terminals listed below with the switch in each appropriate position.
  5. • Tilt Up Switch - control terminal C
    • Tilt Down Switch - control terminal A
    If greater than the specified value, replace the tilt switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Steering Column Replacement
    •  Control Module References for MSM replacement, setup, and programming