Tachometer Inaccurate or Inoperative

Tachometer Inaccurate or Inoperative

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview

Circuit/System Description

The instrument panel cluster (IPC) displays the engine speed based on the information from the powertrain control module (PCM). The PCM converts the data from the engine speed sensor to a 2 pulses/engine revolution signal. The PCM sends the engine speed information via high speed GMLAN serial data circuit to the body control module (BCM). The BCM then sends the information via low speed GMLAN to the IPC to order to display the engine speed.

Circuit/System Testing

Ignition ON, engine ON, verify the scan tool Engine Speed parameter matches the tachometer display.

If the Engine Speed parameter does not match the tachometer display, replace the IPC.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

Refer to Programming and Relearning for IPC setup and programming. Programming and Relearning