Exhaust Resonance Noise at Idle - keywords compressor HVAC moan pipe RPM tailpipe vibration

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Owners may comment of a resonance or vibration noise heard at idle in gear. The noise may intensify if the A/C is turned on. It should be noted that if the engine speed is raised or lowered approximately 50 RPMs the noise will be reduced or go away.

At this time engineering is not addressing the concern for the Avalanche/Suburban/Yukon XL/Yukon Denali XL/Escalade ESV/ Escalade EXT and this is considered a normal characteristic. Varying success has been achieved using exhaust dampener part number 10199232. In some cases as many as seven dampeners are needed to improve the noise. If after installing the dampeners the resonance or vibration is not acceptable to the owner, contact your AVM to pursue other avenues of customer satisfaction and a Field Product Report should be submitted by following bulletin 02-00-89-002D.

If the vehicle is a 2004, bulletin 04-06-01-023 should be performed, as this may correct the concern.

If you are working on a 2003 - 2005 Escalade/Tahoe/Yukon with a 4.8L or 5.3L Engine (VINs V, T, Z - RPOs LR4, LM7, L59) follow bulletin 05-06-01-006.

Please follow this diagnostic or repair 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.