{"id":18434,"date":"2024-03-29T11:55:27","date_gmt":"2024-03-29T15:55:27","guid":{"rendered":"https:\/\/gm-techlink.com\/?p=18434"},"modified":"2024-03-29T12:13:22","modified_gmt":"2024-03-29T16:13:22","slug":"transmission-whine-sound","status":"publish","type":"post","link":"https:\/\/gm-techlink.com\/?p=18434","title":{"rendered":"Transmission Whine Sound"},"content":{"rendered":"

There may be a whine sound heard under light acceleration or when coasting on some 2023-2024 Colorado and Canyon models equipped with the 8L45 or 8L80 8-speed automatic transmission (RPO N8R, MFC). The sound, usually heard around 25-50 mph (40-80 km\/h), may be caused by cable isolation in 4th and 5th gear at approximately 42 mph (68 km\/h) under moderate acceleration.<\/p>\n

To help verify the source of the sound, follow the service procedure outlined in Bulletin #24-NA-002. The procedure covers driving the vehicle in 4th gear, at approximately 2000-2800 rpm, and observing if a gear whine sound is heard under light throttle or coasting. (Fig. 12) The intensity of the whine sound should change along with changes in the throttle position.<\/p>\n

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Fig. 12<\/strong><\/p>\n

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Once the noise is noticed, vehicle speed should be increased to shift the transmission to 5th gear. A similar noise should still be audible in the 2000-2800 engine rpm range while in 5th gear.<\/p>\n

During the test drive, there should not be any gear whine sound with the transmission in gears 1-2 or 6-8, or at engine speeds greater than 2800 rpm.<\/p>\n

Once the sound has been verified under these conditions, install a transmission cable weight to help eliminate cable isolation and the gear whine sound while under moderate acceleration in 4th and 5th gear. (Fig. 13)<\/p>\n

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Fig. 13<\/strong><\/p>\n

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For additional details, including parts information, refer to Bulletin #24-NA-002.<\/p>\n

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\u2013 Thanks to Marty Leach<\/em><\/p>\n