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Loren

Replacing the headlight switch in the dash

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Replacing the headlight switch in the dash


1. Pull forward the control button 25 of the light switch 31 as far as it will go (direction of the arrow) towards the front. 2. Press in the locking device at the lower side using a small screwdriver and remove the control button towards the front. 3. Undo the fastening screws 21 at the side, remove the side vent towards the front. 4. Disconnect the plug connection 30 of the main light switch 31. In order to disassemble the side vent, the covering cap 28, the fastening nut 26 and the inner race 27 of the main light switch 31 can be removed. 5. Remove light switch 31 from the side vent by turning it slightly in clockwise direction.

 

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Thanks for posting. But before I go this route, I'd like to know if someone has advice for troubleshooting a bad switch?

In particular, I have a dim passenger low-beam ('99 996 Carrera). I replaced the bulb - still low. I looked at wiring diagram from Tech manual for U.S. cars. Low beam is across pins 4 and 9 of the 10-pin headlight assembly connector. I measured ~ 12.5V. With high-beam engaged, I measured ~ 12.3V across low-beam and ~ 12.4V across high-beam (pins 1 and 2). However, I cannot find what is normal voltages for low-beam on/off. Can anyone advise? Thank you in advance.

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You should disconnect the battery any time you are doing electrical work.

You should also check to make sure the headlight plug is fully seated in the assembly. To do this, remove the wheel and wheel well liner to access the plug for the lamp.

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No joy <_< I got the switch on "ok", but still have a dim passenger headlight. Still, I appreciate the DIY instructions here. The hard part for me was getting the assembly back in place. No clearance for the screw lugs (that the 2 side screws screw into) (not sure how to keep them in place while pressing the vent back on). Also switch lug didn't protrude enough for the knob to snap back on. I thought it would be automatically positioned when I twisted the switch into place and then retightened fastening nut 26. Was afraid I'd overtighten 26 and crack 27. I'll have to take it off again tomorrow and try again. Then I guess I'll have to go back to debugging.

I'll end up taking off the "known good" driver headlight to measure voltages at the connector for reference. If anyone has any suggestions, would appreciate them.

Also, the connector on the "car" side (i.e., inside the passenger front fender) is firmly attached to a strong metal bracket - That side cannot come loose. All the connector plugs look the same depth (i.e., not pushed out/loose). Nothing untoward on the headlight assembly connector either.

Edited by janebang83

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Perhaps try connecting the opposite headlamp to the weak side to try an eliminate the headlamp itself or wiring. I know that might be difficult though, because it would mean removing the connector from the backside of the light tray and then plugging it in from the wheel well.

"is firmly attached to a strong metal bracket"

Even though it may be attached to the bracket, is the connector itself firmly seated into the headlamp unit's plug? If the tray is not lined up, or cracked, or broken it could cause the symptoms you describe. I've had the exact same issue with a weak light and it was because the connector was not fully seated into the lamp.

"No clearance for the screw lugs (that the 2 side screws screw into) (not sure how to keep them in place while pressing the vent back on)."

Get a helper, or try a magnetic screwdriver.

"Also switch lug didn't protrude enough for the knob to snap back on. I thought it would be automatically positioned when I twisted the switch into place and then retightened fastening nut 26"

If I remember right the switch cover itself just presses/snaps in. You don't need to pull out the switch to do so. It won't automatically position, I think there is a tab that orients it correctly (you must line them up while installing it).

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Thanks for hanging with me on this, logray.

Joys! :thumbup: Problem fixed - and (unfortunately) nothing so evil. First the embarrassing part: I originally changed the bulb as first step (or so I thought) - had replaced (known good) high beam instead of low beam - and I thought for sure I double-checked that (i.e., low beam is actually one on top of headlamp assembly) - did the same thing a month ago on the driver side. :blush:

What threw me off was that the lamp was dim after replacement (rather than fully off). That may still be indicative of something untoward because the bulb element was totally broken - could it really have developed a drop across it to work dimly? If so, why?

So now, I've got to take the headlight switch out again and do a better job of reinstalling it so knob catch correctly attaches. :cursing:

$116 lesson on not working on car late at night when tired...

Thanks again for support/advice - especially the support!

p.s. connectivity between headlamp connector and wire on bulb was fine although, inspecting the wires going into the headlamp side connector more closely, wouldn't surprise me at all if (when) those wires work themselves lose from that connector.

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A tip on the original headlight switch DIY install. At the end (after everything is back in the dash), turn switch to the high beam setting and then pull out for fog-light (with pliers). This will make it easy to snap the knob back onto its post and lock into place.

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Just had the headlight switch out to gain access to the ignition switch. Couple of observations/comments which might help.

 

What isn't mentioned in the DIY is the fact that there are two wiring connections to the switch. The main harness to the rear and a seperate one to item 27 in the drawing, the front bezel.  Further back from this part is a plug and socket junction covered in a 'foam' antirattle cover. See below. Also the tape which covered these wires, as you can see in the picture had gone back to nature and was very sticky.

 

post-363-0-90118400-1418320709_thumb.jpg

 

post-363-0-78932800-1418320739_thumb.jpg

 

 

Secondly when replacing the side vent, make sure the knob that opens and shuts the vent is set to 'open'. It makes reassembly at lot easier.

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Hi, found this informative post as my headlight switch recently failed. I am following the instructions from the drawing, having taken out the switch from the dash, I am stuck on item 27. How do you remove the front bezel? Seems to be fixed to the main harness at the rear. Thanks for your help in clarifying.

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Adding a bit to an older thread. The headlights (low and high) completely stopped coming on recently (2002 Carrera Cabrio), but I could toggle the high beams with the stalk.  Also, the fog lights and parking lights all worked, just no headlights.

 

Was trying to determine if the switch was actually bad before buying a new one, but with about a dozen connections to the harness, I gave up on figuring out what each did.  On a 986 forum, I found a thread that talked about removing the switch, blasting CRC contact cleaner or similar into it.

 

I shot cleaner down the stem and into the 8 or so crimped lugs that hold it together, blew it dry and tested.  And, it fixed my headlights 100%. 

 

Anyway, if you have a similar fault in turning on your headlights, give this a try.  Also, Pelican has a good DIY writeup with photos on R&R the headlamp switch.

Edited by Chuck Taylor

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