This 2001 Chevrolet Impala came in with the complaint of no low beam headlights. The obvious things to check first were the bulbs and the fuses and all were okay. Time to pull the lower dash cover out to access the wiring for the dimmer/combination switch. Remove the screws at the bottom of the cover, pull the top edge of the panel towards the seat in order to unhook the spring clips. Disconnect the trunk release switch and then remove the outer screws and inner bolts from the interior metal bracket.
The harness shown in the next picture is located at the left side of the steering column.
Follow it until you find this connector. It should be clipped to a bracket at the lower right side of the steering column. This one was already hanging down so I knew someone else had already been here.
This picture shows the clip that it should have been attached to.
The white clip has to be flipped or rotated in order to disconnect the harness connector.
With the harness disconnected, I checked to see if I had power on the dark blue wire at position C4. I did and this told me that the power that came from the fuse through the low beam headlight element and through the the wiring harness was intact and doing its job. I attached a ground wire to my test light probe and checked to see if the low beams came on and they did. Unlike older vehicles this Impala uses a switched ground to change from high to low beam. One slightly strange thing that I noticed was that the wire color on the harness side of the connector is dark blue but on the switch side of the connector it is brown. I also noted that the ground control wire from the headlamp relay at position C3 is light blue on the harness side and yellow on the switch side of the connector.
Time to change the combination switch assembly. In order to do this the steering column cover has to be removed and the trick to doing this job easy without having to remove the steering wheel is to use a short bit with a small wrench. The top one is no problem.
The front one takes a little effort and coordinated fingers. I use a small screwdriver to hold the end of the bit down so that it will stay in the screw. There was not enough room to take a picture of all of that though.
Reverse the procedure to install the new switch. The switch wiring will have been held in place by some wire ties and some clips, be sure to install new wire ties and attach all of the wiring as it was originally intended by the manufacturer.
Something extra I took a picture of is the back side of the driver’s interior fuse box. The gray box above the circuit breaker is the headlamp relay. It sends one of two grounds to the dimmer switch.
