Big Rig Basics: Looking glass

Looking glass

Mirror motors improve driving safety by making it easier to reposition safety equipment, and you can easily replace them yourself when needed


Moto Mirrors, now manufactured by the Commercial Vehicle Group, rotate the mirror in either direction with the flip of an on-dash switch. This allows the driver to focus the mirror on the rear of the trailer when backing.

Mirror motors can wear out. Replacing one is a do-it-yourself job for a trucker who has used basic tools. The mirror glass can be replaced at the same time.

You’ll need the following tools and parts to complete this job:

1. Parts kit SK-1526. There will be rivets of different lengths in the kit, designed for servicing different mirrors. You may not need them all.

2. A pop rivet gun that will fit a 1/8-in. rivet shank.

3. A cordless drill and 3/16-in. drill bit.

4. A small vise with soft jaws.

5. If your mirror has a black strain relief plug, get a set of wiring butt splice connectors and tools needed to make splices with them and electrical tape.

6. Pliers.

7. Awl to align rivet holes.

8. With aerodynamic mirrors, you’ll need two 12-in. tie wraps.

Be careful about scratching or damaging the glass by allowing it to contact anything as you handle the mirror body.


one1. Disconnect the power to the mirror by pulling the fuse that supplies that circuit. There is a small plastic plug in the bottom of the mirror called a “strain relief” that protects the wires. Gently squeeze this with a pair of pliers to reduce its diameter and pull it out of the bottom plate. Pull the wiring out gently until you can unplug all the connectors. Note the colors, then unplug the white and green wires going to the motor. If there are no connections, gently pull the wires out as far as possible and cut them three inches below the plate.


two2. Loosen the mounting hex nuts at top and bottom, then remove the nuts and star washers at both locations. Remove the mirror. Don’t lose the star washer at the bottom of the lower mounting screw.



three3. Place the mirror assembly on a work table. There are two styles of mirrors, one with a three-sided body, and one shaped like an airplane wing. Go to step 4 if you have a three-sided mirror. With an aerodynamic mirror, tie the two tie-wraps all the way around the body about two inches from the bottom of the mirror so the body will keep its shape.






four-for-real4. Place the unit mirror on your work table. Hold it as you work or get a helper. Use the 3/16-in. drill positioned parallel to drill the heads off the four rivets that attach the motor to the bottom plate.

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four---a5. Drill off the heads of the five (or six with the aero design) rivets that attach the bottom plate to the mirror body. Pull the bottom plate off the mirror body. Remove all the rivet stems from inside the mirror body.









six6. Remove the motor and transmission assembly from the mirror. Note that, if you have enough wire and can set up your worktable near the truck, you can wait to disconnect the wiring until after the bottom plate is removed. This will make it unnecessary to remove and reinstall the “strain relief” plug. If you also need to replace the glass, do it now. Make sure the glass is securely fitted into the groove in its mounting gasket and that the gasket fits into the mirror body all around. Put the bottom plate in a soft-jawed vise and tighten the vise gently. If you have a helper, he or she can hold the plate and you won’t need to mount the bottom plate in a vise.


seven-a7. Position the new motor above the bottom plate with its shaft protruding through the large hole in the plate. Gently use an awl to align the motor chassis holes with the holes in the plate. Then hold it tight and install each of the four half-inch rivets with the rivet gun.









eight8. Position the bottom plate near the bottom of the mirror body and feed all the wires through the wire exit hole.







nine9. Align the rivet holes gently with the awl. Then, holding the body securely in place, install each of the pop rivets. If you put tie wraps around the body of the mirror, cut them off. Install the star washer onto the bottom mounting screw. Hold it there and then pass the mounting screw through the top of the mounting hole in the lower mounting bracket on the truck. Next, make sure there is still a star washer above the hex nut on the top mounting screw, then pass the upper mounting screw through the hole in the upper bracket. Install another star washer and the hex nut to the bottom of the lower mounting screw below the bottom mounting bracket.


ten10. Install the upper star washer and hex nut on the top of the upper mounting screw. If the bracket is too tall for the mirror, adjust the hex nut that is just below the upper mounting bracket by turning it so it moves upward. Don’t adjust the hex nut at the bottom. Tighten both hex nuts securely.






eleven11. Slide the strain relief-plug over the wires, squeeze it and install it into the wire exit hole. If the strain relief plug is gray, just reconnect all the wires to similar colored connectors. If it’s black, splice the wires from the mirror cable to similar colored wires in the harness from the truck with butt connectors. Then insulate all the butt splices with electrical tape to keep moisture out.


For providing info and photos, special thanks to Commercial Vehicle Group’s Logan Mullinix, vice president of R&D, and his associates Susan Cline, contractor administrator for truck products, and David May, applications engineer.



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