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Saturday, June 18, 2016

Chevy Tahoe Tachometer does not work

Super Ignition Switch

What is the solution when the key in your customer’s vehicle turns way too easily? Either you gained super strength overnight or the ignition switch housing is damaged. The second option is probably your best bet. You don’t need super powers to solve this issue, just this Real Fix and a little time.

Auto Repair Manuals

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Vehicle2003, Chevrolet Tahoe, 5.3L
Tachometer Inoperative, Repaired Engine Wiring Harness

The customer states the vehicle’s tachometer does not respond to the change in engine speed.


Performed a road test to duplicate the customer’s concern and found the vehicle’s tachometer did not respond to the change in engine speed. Performed a road test while monitoring live data on the scan tool and observed the tachometer readings differed from the engine speed data parameter readings. Connected a lab scope to the RPM OUT terminal at powertrain control module connector 2, measured the voltage signal, and observed the signal did not change when the engine speed varied. Disassembled the engine wiring harness, traced the RPM OUT circuit and discovered the RPM OUT wire had stretched in the engine wiring harness, which caused the open circuit.

Repaired the engine wiring harness, cleared codes, performed a road test and verified the vehicle operated properly.


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