News Technical Service Bulletins

Loss of AWD for Buick

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KEYWORDS Buick Mitchell 1

Note the location of harness clips.

On some 2013-2018 Buick Encore vehicles equipped with all-wheel drive (AWD) over an extended period of time, road splash may enter the rear differential clutch control module (RDCM), promoting internal corrosion of the module circuit board.

This may create a loss of all-wheel drive function, or in rare cases, a dead battery or loss of power steering assist. 

Check for an engine light or service AWD message on the driver display. Check for a dead battery. Check for loss of communication on HSLAN (high speed LAN). Check for loss of power steering assist.

Diagnostic trouble codes (DTCs) C0800 and/or U0136 may be set. 

1. Lift the vehicle.

2. Inspect the RDCM connector for corrosion. If there is no corrosion evident in the connector, proceed to Step 10. If there is corrosion, replace the harness.

3. Disconnect the harness at the RDCM and remove the indicated clips.

4. Remove the left rear wheel.

5. Remove the nut from the rear wheelhouse liner.

6. Disconnect the body end of the harness from behind the rear wheelhouse liner and remove the entire harness from the vehicle.

7. Install a new harness, being careful to route and secure the harness in the same manner as the original harness. Do not install the module end of the harness until the RDCM has been replaced.

8. Reinstall the nut to the rear wheelhouse liner and tighten to 16 in-lb.

9. Reinstall the left rear wheel.

10. Remove the RDCM.

If the replacement RDCM is P/N 42463357, inspect the replacement RDCM for the presence of a green dot on the tag. If the replacement RDCM has a green dot, go ahead and install it. If the RDCM does not have a green dot, order a new RDCM. Do not install an RDCM that does not have a green dot. Note that future RDCMs may not have a green dot. In that case, verify that the part number 42463357 supersedes the current part number you have received.

Install the new RDCM and lower the vehicle.


Note location of the nut on the rear wheelhouse liner.


The replacement RDCM should have a green dot on the tag.

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