{"id":21514,"date":"2026-08-14T15:15:00","date_gmt":"2026-08-14T19:15:00","guid":{"rendered":"https:\/\/gm-techlink.com\/?p=21514"},"modified":"2026-08-14T15:52:54","modified_gmt":"2026-08-14T19:52:54","slug":"gear-shift-control-module-contamination","status":"publish","type":"post","link":"https:\/\/gm-techlink.com\/?p=21514","title":{"rendered":"Gear Shift Control Module Contamination"},"content":{"rendered":"

If one of the Gear Shift Control Module buttons (Fig. 6) is stuck on a 2022-2026 Silverado 1500, Sierra 1500 or HUMMER EV, check for any liquid spills that may have contaminated the shift lever.<\/p>\n

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Fig. 6<\/strong><\/p>\n

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Contamination of the Gear Shift Control Module also may result in an illuminated Check Engine MIL along with DTCs P17F4 (Transmission Range Selector Enable Switch A\/B Circuit Stuck On), P189D (Transmission Park Position Switch A\/B Circuit Stuck Off), P07B2 (Transmission Park Position Sensor\/Switch A Circuit\/Open), and\/or P07B8 (Transmission Park Position Sensor\/Switch B Circuit\/Open) set in the Engine Control Module. Any of these DTCs may be caused by contamination if liquid has penetrated the buttons or internal components of the shifter. (Fig. 7) If the shifter has been cleaned, evidence of a spill may not be easy to identify.<\/p>\n

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Fig. 7<\/strong><\/p>\n

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Inspect the gear shift lever for signs of liquid contamination (Fig. 8), including the top edges as well as the base of the shifter. (Fig. 9) Clean the contaminated areas with a microfiber towel.<\/p>\n

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Fig. 8<\/strong><\/p>\n

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Fig. 9<\/strong><\/p>\n

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After cleaning the affected areas, cycle the shift lever through each selection multiple times, including the side release button and Park button with the ignition\/power on and engine off (Silverado and Sierra models). Cycle the shifter a minimum of 10 times.<\/p>\n

Use a scan tool to clear the DTCs and monitor for any codes setting.<\/p>\n

Next, start the vehicle, apply the brake and cycle the shift lever again. If the buttons are no longer stuck and the gear selections can be made without any DTCs returning, repairs are complete.<\/p>\n

If either button is still stuck or if codes return, the Gear Shift Control Module should be replaced. (Fig. 10) Refer to Gear Shift Control Module Replacement in the appropriate Service Information.<\/p>\n

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Fig. 10<\/strong><\/p>\n

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For more information, refer to Bulletin #26-NA-142.<\/p>\n

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– Thanks to David MacGillis<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

If one of the Gear Shift Control Module buttons (Fig. 6) is stuck on a 2022-2026 Silverado 1500, Sierra 1500 or HUMMER EV, check for any liquid spills that may […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"categories":[239],"tags":[],"class_list":["post-21514","post","type-post","status-publish","format-standard","hentry","category-2026-august-a"],"_links":{"self":[{"href":"https:\/\/gm-techlink.com\/index.php?rest_route=\/wp\/v2\/posts\/21514","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/gm-techlink.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/gm-techlink.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/gm-techlink.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/gm-techlink.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=21514"}],"version-history":[{"count":2,"href":"https:\/\/gm-techlink.com\/index.php?rest_route=\/wp\/v2\/posts\/21514\/revisions"}],"predecessor-version":[{"id":21536,"href":"https:\/\/gm-techlink.com\/index.php?rest_route=\/wp\/v2\/posts\/21514\/revisions\/21536"}],"wp:attachment":[{"href":"https:\/\/gm-techlink.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=21514"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/gm-techlink.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=21514"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/gm-techlink.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=21514"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}