Tachometer Inaccurate or Inoperative

Tachometer Inaccurate or Inoperative

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

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

Circuit/System Verification

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