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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1326 (Instrument Panel System Displays, Gauges And Console) >> Diagnostic Information and Procedures >> Tachometer Inaccurate or Inoperative

Tachometer Inaccurate or Inoperative

WARNING: This page is about a different car, the 2004 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
Tachometer Inaccurate or Inoperative

Step Action Yes No
Schematic Reference: 
1 Did you perform the Instrument Cluster Diagnostic Starting Point? Go to Step 2  Go to
2
  1. Install a scan tool.
  2. Start the engine.
  3. With the scan tool, observe the Engine Speed parameter in the Engine Data list.
Does the Engine Speed parameter match the tachometer display?
Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 3 
3 Using a multimeter, Inspect the Instrument Panel cluster Engine Speed Output circuit cavity 27 for 6.5v-7.0v. Refer to Testing for Intermittent Conditions and Poor Connections in wiring systems
Is voltage within specified value?
Go to Step 6  Go to Step 4 
4 Using a multimeter, Inspect the PCM Engine Speed Output circuit connector 4 cavity 5 (C3 cavity 3 LNK) for 6.5v-7.0v. Refer to Testing for Intermittent Conditions and Poor Connections in wiring systems
Is voltage within specified value?
Go to Step 5  Go to Step 7 
5 Repair the open or high resistance in the Engine Speed Output circuit between PCM and the I/P. Refer to Wiring Repairs in Wiring Systems
Did you complete the repair?
Go to Step 8  -
6 Replace the IPC. Refer to Instrument Panel Cluster (IPC) Replacement .
Did you complete the replacement?
Go to Step 8  -
7 Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?
Go to Step 8  -
8 Operate the system in order to verify the repair.
Did you correct the condition?
System OK Go to Step 2