Audio System - Noise on AM Band
TECHNICALBulletin No.: 08-08-44-006
Date: February 27, 2008
Subject:
AM Band Noise, Radio Noise (Install Resistor)
Models:
2008 Chevrolet Silverado
2008 GMC Sierra
with 6.6L Duramax(TM) Engine (VIN 6 - RPO LMM) and RWD Allison(R) Transmission LCT1000 (RPO MW7)
Condition
Some customers may comment on AM band noise occurring while driving. It is acutely apparent when listening to the AM radio and driving under a viaduct on the highway.
Cause
This noise may be generated by the engine control module (ECM) timing signal. This signal then radiates into the AM band, causing interference.
Correction
Technicians are to add a 330 ohm resistor in series with the 1827 circuit, pin X2-54 (yellow/black) on the engine control module (ECM) side.
1. Locate ECM connector X2 (the bottom connector) under the hood.
2. Locate pin # 54. Refer to Connector End Views in SI for the ECM X2. The wire is yellow/black in color.
3. Cut the wire about 178 mm (7 in) away from the connector.
4. Slide about 76 mm (3 in) of heat shrink tube on one end.
5. Solder the 330 ohm resistor in series with the 1827 circuit. The resistor is non-directional.
6. Heat shrink and tape the harness.
7. Reconnect the connector to the ECM.
Parts Information
Obtain 330 ohm, 1/4 watt resistor from a local Radio Shack(R) (in Canada, obtain an equivalent part from The Source by Circuit City).
Warranty Information
For vehicles repaired under warranty, use the table.
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