Hi all,

Since the old thread on this hasn't got pictures anymore, and these switches becoming rare/expensive to repair/replace, I figured I'd share my experience in opening one up.
I'm not gonna cover any of the actual components on the circuitboards, cus I'm no electrical engineer and it's beside the point. That said; let's jump in!

- Getting the switch out of the car. This is covered in the Factory Service Manual, but to break it down:

- Part the Instrument Cluster Surround from the Instrument Cluster
- Undo the connectors on the back of it
- Undo the indicator lever (1 screw in the crook of the lever)
- Remove the indicator switch from the surround (2 screws on the back of the surround)

- Remove the buttons from the headlight switch. Just gently pull/pry them straight out of their sockets:



- Remove the last, big button. Again, just pull straight out:



- Now undo the 2 screws holding the headlight switch in the surround, and wiggle 'er out:



So far so good. Now let's get to actually opening this thing up

- Flip the switch over:



- Gently pry the plastic cover off the backside of the switch. There's a few tabs all around it, but once you've carefully undone the bigger ones on the front edge the rest will pop loose with some gentle wiggling:



- Once you've got the cover off, you'll be looking at the bottom of the main circuitboard:



- There's 3 screws on this side, that have had their heads tinned over from factory. Don't bother with them. Screws A and B hold the connector to the board, and screw C holds some parts on the other side.



- Instead, desolder all these connections:



- Once completed, the circuitboard is now no longer connected to anything crucial and can be gently pried from the case:



- Flip it over and there's all your components. If the switch fails this is where repairs will have to be made. One of the recommends is replacing the old relay (the see-through bit) with a modern one as this is prone to failure, but I don't have part numbers handy. Maybe someone can chip in? I also noticed a shorted-out trace on the board below point 10 that will have to be fixed:



Hope this helps

 

Something someone suggested while at this is cleaning up the contacts of the switch itself, so let's go for it.

- Flip the case over, revealing the small brown PCB:



- Desolder this single contact:



- Then pry the PCB out of the white plastic case, by working it past these four little tabs:



- Once done you can lift the board straight up, working the pins in the back up and out of the white plastic case:



- CAUTION: Don't move the white plastic part on the PCB, and as soon as you can reach it - mark it's position:



- This bit meshes with the headlight button and it's position is critical to the functioning of the headlight switch:



- Now that that's out of the way, you can remove the black plastic bit that it meshes with. Be careful lifting this out, as there's a little spring and a ball that make up the ratchet mechanism of the Instrument Panel dimmer switch:



- After having removed that, you can pry the white plastic cover out of the switch case. There's five tabs holding it down. Number 1 and 2 can be worked loose enough for a small spacer or screw to be inserted underneath, keeping them from snapping back in place. Number 3 can then be undone, this one's a bit tricky but with some effort can be done. Once you've got those 3, numbers 4 and 5 will follow easily enough:



- Lift the white plastic cover out of the way, revealing the switch mechanism. Go ahead and clean the interior of that, and dunk some dielectric grease in to lube everything up:



- Now go back to the small white plastic part on the PCB; use some sanding paper to carefully clean the 4 springy contacts on the bottom of it, then get some dielectric grease on the tracks the contacts run on, and clean the rest of it:



- That's the contacts sorted, should be good for a while now. Installation is the reverse of removal. Make sure to clean any old lubricants and dirt from the parts, and re-grease anything that had lube on it, i.e. the black plastic part with the spring and ball, and the toothed track in the white cover that the ball rides over. Now close everything back up and you're golden

 

Thank you for starting the thread. The high beam indicator light stayed on and the instrument cluster wasn’t lit on my car. I obtained a light switch from a friend. After replacing the light switch, the instrument cluster lights were functioning but, the high beam indicator light was still staying on. Any idea what the problem is? Perhaps the light switch from my friend was also defective?

 

I couldn't tell you, I'm not really versed in electronics.. Maybe someone else can chip in?

 

Mazdarian,

btw what issues were you having before you decided to take the switch apart? Did you end up fixing a fault inside the switch?

 

This switch probably saw a voltage spike due to a short or faulty component, burned out a few traces and components on the board. This will be repaired, yes.