Chicagoland MG Club: Driveline October 2009

Turn signal/hazard Warning
Switch Repair-Late Model MGB
by Bill Cole

Because my mechanical turn signal return is poor to non-existent, I was often accused of being a “blinker buddy”, with the signals going for miles after a turn. As I couldn’t hear the blinkers, and the steering wheel interfered with my view of the turn lights on the dash, I remedied the problem by adding a buzzer across the blinker relay, which was loud enough to be heard over significant road noise. That buzzer sound, or lack of, led me to discover that the hazard warning switch is the point of electrical interconnection for the turn signals, and I had to operate that switch several times before the turn signals would work. This is the area to look into for any of you who are experiencing intermittent turn signal operation. OK, I could live with that as long as I remembered to operate the switch a few times each time I drove the car.
Last week, driving to the Orphans Picnic, the problem grew more acute. Now I had to physically hold side pressure on the switch to make the signals work. Time to do something about it.
I removed the switch from the dash, which is pretty simple once the lower valence is removed (three screws). Once out and disconnected, I checked pricing on a replacement. The catalog price of forty bucks caused me to look again at the old switch, and to my delight, I discovered it is repairable. The switch consists of three sections; the rear which contains the contacts, the center which contains the spring-plungers which actuate the switch arm, and holds a bulb which illuminates the hazard label on the rocker, which is the last of the three parts. The rocker removes easily (not necessary for switch repair, but good to know) as it must to replace a burned out bulb. Simply grasp the rocker and pull forward. It should come straight out, although a little prying on the side with a jeweler’s screwdriver helps.
The rear section is held to the middle by hooks down the length of both sides of the switch. I used a small screwdriver to pry the two pieces apart, but not until I had scratched matching marks on the top and sides, so I would be sure to get it back together properly. Once apart, carefully remove the plastic actuators and their springs from the middle section, then the H shaped switch arm from the rear, noting its relationship to the contacts. All six contacts should now be visible. Mine were covered by green verdigris, and that was obviously the source of the problem. A q-tip removed the old, dried lubricant, as well as some of the verdigris. I initially used a small fiber blade as a scraper to clean the contacts, which were in excellent shape otherwise. That got some of it, but I had to use my jeweler’s screwdriver to remove the rest. The contacts were then polished using some fine emery cloth on the end of a pencil eraser, then polished with the eraser itself. The H shaped switch arm must be similarly cleaned.
Once polished, the contacts were covered with a liberal coating of silicone (dielectric) grease, the H contact arm installed, the actuators installed, the parts were matched up and snapped back together, and voila, I had saved forty bucks. Everything now works as it should. When reassembling, don’t forget


the spring retainer that goes between the two main parts. I did, and had to open it all up again, as the switch won’t stay in the dash without it. Also, when reconnecting, don’t forget the side contacts. These are power and ground for the internal lamp.

This repair technique should work for most of the rocker switches used on any year MG.

  Inset from "MGB Repair Operation Manual,
  1978". Page 86-18

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