Endgate Closure with Accessory Tonneau Cover

After installing an accessory tonneau cover on some 2019-2020 Silverado 1500 and Sierra 1500 models and 2020 Silverado 2500HD/3500 HD and Sierra 2500HD/3500HD models, the endgate may fail to auto open or manually close. The improper operation of the endgate may be caused by excessive interference between the endgate and the tonneau cover. (Fig. 32)

Fig. 32

If the tonneau cover is a GM accessory, the cover can be adjusted to reduce compression at the endgate interface. GM tonneau cover part numbers are listed in Bulletin #20-NA-044.

If the tonneau cover is non-GM (IBP), contact the manufacturer of the cover for specific adjustment instructions. Non-GM tonneau covers can be identified by non-GM branding. Contact information for the manufacture can be found with the installation instructions provided with the kit, or by searching the part number in the Electronic Parts Catalog.

First verify if the condition is related to the tonneau cover by ruling out the endgate lock actuator as the cause of the condition. Open the rear end panel of the tonneau cover and cycle the power endgate five times. Use the tailgate switch or key fob to power open the endgate and then manually close the endgate. If the endgate functions properly, continue with adjusting the tonneau cover. If the endgate does not function properly, refer to Bulletin #20-NA-040 for more information about the endgate lock actuator.


Adjusting the Side Rails

To make the necessary adjustments to the tonneau cover, the cover must be removed and the side rails adjusted upward and forward. There are three different tonneau cover fastener styles. (Fig. 33)

Refer to Bulletin #20-NA-044 for complete details on removing/installing the tonneau cover and adjusting the side rails.

Fig. 33

Once all adjustments have been completed, close the tonneau cover and cycle the power endgate five times to verify the condition is corrected. Also open and close the front panel to verify the latches have efficient engagement.

If additional adjustments are necessary, reference the Hard Tri-Fold Cover Instruction Sheet. (Fig 34)

Fig. 34

Refer to Bulletin #20-NA-044 for additional information and fastener torque specifications.

– Thanks to Kevin Minor, Dave MacGillis and Pete Allen

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