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 C2173: Engine Speed Signal or Vehicle Speed Signal Performance

Circuit/System Description

The tire pressure control module receives a vehicle speed signal from the IPC and an engine speed signal from the PCM. The tire pressure control module utilizes these signals to detect DTCs C2121-C2124 and C2177.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

    • No engine speed signal while vehicle speed is greater than 5 mph for 15 minutes.
    • No vehicle speed signal while engine speed is a specified value for 15 minutes.

Action Taken When the DTC Sets

The Tire Pressure Warning Light is illuminated.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists.

Reference Information

Description and Operation

Tire Pressure Monitor Description and Operation

Schematic Reference

Tire Pressure Monitoring System Schematics

Connector End View Reference

Component Connector End Views

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 Testing

  1. With the scan tool, place the system in Test Mode and enter signal check mode.
  2. Start the engine and increase the speed to 1000 RPM for 3 seconds or more to erase DTC C2194, then drive the vehicle at 12 mph or more for 10 seconds to erase DTC C2191.
  3. If DTC C2191 is still present, refer to DTC C2191 . If DTC C2194 is still present, refer to DTC C2194 .

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Tire Pressure Sensor Learn
    •  Control Module References for module replacement, setup, and programming