Dashboard lights and number plate lights not working

[mailric]

Hello,

Got an '03 Boxster S and the instrument panel lights are not working. The LCD displays are fine but the rest of the dash is just in darkness.

Also, the number plate lights are not working.

I checked the fuse as the book says they are both on the same one... but fuse is fine. Changed it anyway just in case, no change.

Checked the bulbs in the number plate and they were both bust. Replaced them and still no joy. There was some green (limescale?) cr4p on the connectors so cleaned 'em up a bit. Also in one of them you could tell a bit of water had got in, thus causing the limescale I assume. However if this was causing a problem I would assume the fuse would go?

Reluctant to take it into Porsche Centre as when it was in for service the other week they quoted £70 to replace the number plate light bulbs... so god knows what they would charge to resolve this problem when they realised after they had replaced them they were still not working!!!

Any ideas? Much appreciated.

[RFM]

Have you already checked the ignition and/or light switch ?

[mailric]

Have you already checked the ignition and/or light switch ?

No. What about it?

[RFM]

They are known to fail with strange behavioural effect.

[mailric]

They are known to fail with strange behavioural effect.

Any ideas how to fix it? Is it a new ignition or light switch?

[Glyn]

More than likely this is the light switch, happened on mine last week, changed the light switch.

To test the switch - turn it to sidelights on, pull the switch out to put the fog lights on - now give the switch a whack with your hand to push the switch back in (Fogs off) - hey presto your instrument illumination and numberplate lights are now on (They are on the same circuit)

[mailric]

More than likely this is the light switch, happened on mine last week, changed the light switch.

To test the switch - turn it to sidelights on, pull the switch out to put the fog lights on - now give the switch a whack with your hand to push the switch back in (Fogs off) - hey presto your instrument illumination and numberplate lights are now on (They are on the same circuit)

Will go give it a try now... btw the 'bong' has gone when my lights are on and the ignition key is out. Same problem???

[mailric]

Nope, gave it a good thump and nothing.

Sounds like its the cause though. How much was that new switch and was it hard to fit?

Cheers

[1schoir]

Will go give it a try now... btw the 'bong' has gone when my lights are on and the ignition key is out. Same problem???

Now that you have no "bong" when the lights are on, it points a little more surely to the ignition switch, as RFM said.

Do a search here for replacement instructions.

The part # is (it's an Audi Part Number) 4A0-905-849-B, recognized as the replacement ignition switch part of choice for 986's and 996's.

You can get the switch for around $10 from AutohausAZ, and you can also get it for a decent price from Sunset Imports (link at the top center of this page).

Regards, Maurice.

[grover]

04 986S

Last two times I turned my lights on... no dash lights. Both times, they snapped on during a slow but hard turn- first time (after about 30 seconds) a right turn, second time (after about 5 minutes), a left. The 2nd time, in my garage, I turned my lights off and back on with the car running. The headlights briefly (like 1/4 second) came on real dim, like happens without the key in, and then came on full. And the dash lights stayed out. I don't recall the car bonging when I pulled key and THEN killed the lights, but I didn't even think about it until searching on here.

Any specific tests I can do to verify it's the ignition switch vice the light switch? And is it important to disconnect the battery before this repair, or can I just go ahead and yank the connector?

Edited September 18, 2009 by grover

[Glyn]

Despite what you will be told you can take apart the lightswitch very easily.

It has crimped metal surround and all you do is prise the metal out of the detents - it then comes apart - no fiddly bits or springs to fall out.

In side is just bent over and springy copper connections, a slight rebend is all thats needed.

If you have no other electrical issues then i would rule out the ignition switch though this is a common part to fail, The lightswitch however is even more prone to failure and usually it is the number plate lights and dashboard lights that indicate the fault.

Normal for this symptom to be lights do not come on - then for no apparent reason during a journey for them to suddenly come on.

Easy job to change over and cheap

[grover]

If you have no other electrical issues then i would rule out the ignition switch though this is a common part to fail,

I think I answered my own question with the observation of the lights going in key-off mode briefly last night before coming on full. If the light switch had failed, they would either be on full, or off. The ignition switch, however, would control the relay that tells them to be on dim/full, and since this part was intermittent, it's the connection that's failing. Does that make sense?

Just tried it again now, and the lights worked with no issues. I ordered a new ignition switch, should be here some time next week.

Thanks for the advice on the light switch! When it fails, I'll just go ahead and fix it myself :)

[grover]

I've got the switch on hand, but am second-guessing myself based on this thread and hesitant to replace it... so I did some more troubleshooting today to narrow the cause down. When this problem occurs, my instrument cluster lights are out, as are every button in the cockpit. All other lights, including the head lights and license plate lights are on as normal, though.

I've been trying to go through the wiring diagram and pinpoint the point of failure. I think I'm not getting the "lights on" signal to pin A19 (Term 58), which would most likely be a failure in the light switch. However, it looks like the license plate lights come off Term 58, and they have power. The Bentley manual has errors on this diagram, though: EWD-62 has continuation line K, but no D. EWD-63 has D, but no K. How is this actually wired? Where's that 2nd wire from Term 58 going, if not to the license plate lights?

Edit: I sent an email to Bentley as well.

Edited October 3, 2009 by grover

[grover]

Turns out there is, indeed, an error in the leader lines in the Bentley manual. They acknowledged it, and added it to the errata: https://wiki.bentleypublishers.com/x/AwDwAQ

After poring through the electrical diagrams long enough, I eventually traced my the problem with near certainty to the light switch, pin KL58. I procrastinated fixing this, but it's gotten worse and worse until the instrument lights just aren't coming on at all and I can't read my tach, gas gauge or temp at all on my morning commute. Finally got around to fixing the light switch today. Had a bit of trouble undoing the crimps with a screwdriver and pair of needle-nose pliers, but not too bad (Thanks for the tip, Glyn, you saved me $120!!!) Fascinating how it works; it's not at all like I pictured it. The rotating knob part only contains plastic cams that hold the sprung copper contacts open, or allow them to close, depending on the position of the switch. The white dilly at the bottom rotates when you pull it out to turn on the fog lamps. I found that weak springs weren't the problem at all in my case, but that one contact was bad. With the cams removed, all the springs should be closed, and all appeared well. It was closed, and all springy, but I got out my multimeter anyhow... and continuity test failed on pin KL58. EUREKA! Touching the terminal was enough to make the connection, though. Cleaned the contacts with a bit of sandpaper and electronics cleaner, and, reassembled, and works great :D

My probe is pointing to the faulty contact, KL58 (Simply "58" on my switch):

I couldn't get the crimps as tight as the factory, so I hot glued them as well.

Edited January 16, 2010 by grover

[1schoir]

Turns out there is, indeed, an error in the leader lines in the Bentley manual. They acknowledged it, and added it to the errata: https://wiki.bentleypublishers.com/x/AwDwAQ

I procrastinated fixing this, but it's gotten worse and worse until it's just not coming on at all and I can't read my tach, gas gauge or temp at all on my morning commute. Finally got around to fixing the switch today. Had a bit of trouble undoing the crimps, but not too bad (Thanks for the tip, Glyn, you saved me $120!!!) I found that the springs weren't the problem at all in my case, but the contact was bad. With the cams removed, all the springs should be closed, and all appeared well. It was closed, and all springy, but I got out my multimeter anyhow... and continuity test failed on pin KL58. EUREKA! Touching the terminal was enough to make the connection, though. Cleaned the contacts with a bit of sandpaper and electronics cleaner, and, reassembled, and works great :D

My probe is pointing to the faulty contact, KL58 (Simply "58" on my switch):

I couldn't get the crimps as tight as the factory, so I hot glued them as well.

Excellent work! :clapping:

Thanks for posting the solution and the photo.

Regards, Maurice.

[grover]

For those curious, here's what both halves of the inside of the switch looks like:

If anyone else has this problem and finds this thread, the procedure on page 94-5 of the Bentley manual shows how to get the switch out. You'll need a short-handled torx screwdriver, but it's easy to get to without contortions and it came out without too much cursing. There are some clips not mentioned, but pull hard enough once the 3 screws are out, and it will come out. There are no clasps on the large connector; careful use of a flathead screwdriver will split them. (VERY careful use if you haven't disconnected the battery.) The little connector is straightforward. My biggest tire iron got the retention nut off the switch; it's not on very tight, just a big nut. The hardest part was undoing the crimps to split the switch open; I attacked it with a needle-nose pliers and screwdriver until I could get it to split. The plastic bit on the end rotates freely, but alignment is obvious and it was not hard to align for reassembly. I used a hammer and cold chisel to recrimp after the repair, but it didn't work so well and was still loose, so I just ended up gluing it. I hope it holds!

Edited January 16, 2010 by grover

[Mr. Boxster]

I've got the exact same problem.

2004 550S Spyder (986S Ltd. Edition) I bought brand new.

It started with the cluster (and button) lights going off for a few minutes. Over the last few weeks it would take longer and longer for the cluster lights to come on after I turned on the headlights. Now I haven't seen cluster lghts in a few days, no matter how long I drive at night. I miss not seeing the tach the most.

I'll do this fix over the weekend. This was the best post I have found on this problem in the hours I've been searching - it's the exact problem and repair is well documented.

I'll let you know when it's done.

Thanks VERY much!

Mike.

2004 550S Spyder LE (cocoa) 1366/1953

[dsalmons]

Thanks to all who have posted on this thread, especially the photos. My dash lights stopped working too. I pulled the light switch, got it apart, cleaned it, reassembled it and finally tried it out tonight. Bingo! the instrument lights came on as soon as I turned the switch. Hopefully the fix will last a long time because I don't think the metal cap on the switch will stand another uncrimping and recrimping.

Daryl

2002 Boxster S

Speed Yellow

[clowntrigger]

And it worked for me too. I pulled it apart and hit the contacts with 600 grit sandpaper. I lightly buffed each one. I was able to put it back together with a chisel pushing the tabs back in. most of the broke off, so i did the edges.

[clowntrigger]

And it worked for me too. I pulled it apart and hit the contacts with 600 grit sandpaper. I lightly buffed each one. I was able to put it back together with a chisel pushing the tabs back in. most of the broke off, so i did the edges.

Well, my handiwork only lasted about 6 weeks. I bought a used switch that works from a salvage vehicle. We'll see how well it does long term.