Exhaust Moan at 1,500 to 1,800 RPM - kw 3.5 GMT355 idle L52 noise off vibration

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Exhaust moan from 1,500 - 1,800 RPM

The following information only applies to 2WD Regular Cab trucks that were built prior to April 5, 2004 and equipped with a 3.5L Engine and Coil Spring Front Suspension (No Torsion Bars). If the SI diagnostics did not isolate a concern, an updated front exhaust pipe can be installed to address this concern by ordering the following part numbers:

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15139252 - Front Exhaust Pipe

15138532 - Rear Engine Mount

15173581 - Harness Bracket

11514597 - Nut

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

(04 Chevrolet Colorado S1 ) and (04 GMC Canyon S1)

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