Keith526

Hello Guys,

From reading many other posts I understand that my problem with these lights could be caused by a faulty Brake Light Switch. Okay, so today I got the lower half under the dash apart and I think I see the switch! HELP! I don’t have a clue how to remove it. Squeeze and twist? Pull? Or am I looking at the wrong switch? there is a bunch of wires and switches under here. Please does anyone have photos? Or a description?

On a really interesting side note; with these warning lights on it seems that traction control is turned off! The car spins the tires at will If I don’t get this fixed I will have to get new rear tires because I cannot stop poking it, it is really fun to drive without the traction control!!!

Any help would be greatly appreciated!

BJonesFL

Keith,
If you're in the US and have a library close to you, call them to see if they provide free access to AllData, the on-line repair service. You can look up the specifics for your model year car and get drawings and step x step.

Or for $24.95/yr, you can buy a subscription for your car at www.alldatadiy.com that has the information you want which you can access from home or office.

But before you do anything, if you haven't pulled codes based on the light show you've got going, my next stop would be AutoZone or a local indy service provider to pull the codes and verify the brake switch is really the problem. When I had a similar symptom, it turned out to be low voltage output from the battery, so check the codes...AutoZone does it for free.

Bob

Keith526

Hey Bob,

Thanks for the info. This is a good point! I guess I got excited about the 20 dollar cost of the switch and didn't want to think it was anything else, I am going to head down and see if I can get the codes read from AutoZone. I have a code reader for OBDII that I purchased for 120 dollars a few years ago for my chevy. What kind of reader can be used for the 99 SL500?? I love this car so I'm going to need it. As for the www.alldatadiy.com, I heard about this site but didn't trust that it had any valuable info. 24 buck per year is well worth it if it has good info on the SL500. Thanks again for all the great info I will let you know what codes came-up

BJonesFL

Keith,
Your welcome.

Your OBDII scanner will work on the MB! Make your trip to the library to check the codes free on AllData before you invest. AllData lists all the codes/interpretations and provides a search tool and links to appropriate fixes. Try it before you buy it.

Bob

Keith526

Thanks, I will post the results!

Rocco Vespe

Wow,
I am having the same problem (99 SL500) and have ordered the brake light switch because I am hoping that it the problem. I had the battery checked at Autozone and they said it was good. I am definately interested in how your situation turns out. I had been trying to figure out what causes these lights to go on. When I restart the car they go out and then they go on seeemingly unrelated to my driving. I do know that if I take a long ride on the turnpike with no braking the lights stay off. I also noticed that when the lights are on the cruise control will not engage. Are you having the same problem when the lights are on??
How many miles on your car??? Mine just turned 60K and I changed the plugs, all 16 of them. Better performance and better mileage immediately.
Thanks,
Rocco - Mt. Ephraim New Jersey
1999 sl 500
2001 xj8
1988 xjs convertible
1982 xjs coupe

BJonesFL

Rocco,
Did you pull the DTC's (Diagnostic Trouble Codes)? Which one(s) came up in the display?

Bob

HLG600

Try this. While the engine is running, turn the wheel as far as it can go to the left, and then the same to the right. Repeat this one more time, then straighten out the wheel, turn off the motor, wait a moment, and restart. These instructions are found in the owner's manual as well. Good luck!

Rocco Vespe

can I pull diagnostic codes when if I turn the car off and on the lights go out?? I thought the lights had to be on when the codes were pulled.
If so I can go to autozone and have them do it.
Thanks,
Rocco

Keith526

Hey Rocco, I got the OBD-II connected and the result is; no error codes! Arrgghhh!!!!

I just ordered the switch and this is where my path begins to resolve this issue. My car has 63K on the clock. You changed the plugs huh? Difficult job? What plugs did you use? I haven’t tried the cruise control yet, I will today.

I really just gotta stop spinning the tires!!!!!! Otherwise the car seems unaffected by these lights.

Hey Bob is a Diagnostic Trouble Code the same as an OBD code???? I tried the steering wheel thing once to the left then once to the right and no change, but it sounds like you repeat the process twice! I must try again!

Thanks guys!!

BJonesFL

OBD=On Board Diagnostics
DTC=Diagnostic Trouble Codes

At the risk of getting caught up in our acronym underwear, these are functionally equivelant in that you end up with a code that points you toward the root cause of a symptom you're seeing.

To the other post, to read OBD Codes, it's my understanding that the warning lights have to be illuminated, i.e., showing a live fault, and the ignition key on/engine running. This setup is the same that my tech has me do when he uses his OBD scanner instead of the MB Star Diagnostic.

Bob

Keith526

Hello Bob,

I am most familiar using the OBD-II scan tool with all of my other cars; Chevy, Ford and a Volvo with an OBD-I. The codes are pretty simple to read and the values can be found all over the internet. My 1999 SL500 was on factory warranty for the first 5 years, I only raised the hood to admire the 5.0 with the black dress.

It has however been off the dealership tit for the last few years and this is the first issue to arise. This car has officially become one of the cars that I work on myself. I don’t know why I was so surprised that the simple OBD-II scan tool could be used on this car only to be disappointed by zero codes to go with my dash lights. Bone of contention! You say “engine running”?? All my other cars are read at ignition position II! I checked my SL500 with the engine off! Could you please verify this for me? Engine running is new to me with this scan tool.

Thanks

Rocco Vespe

Keith,
I had the codes read and same as you - no codes came up with the ignition on and of course the lights off. I did not try with the motor running and the lights on.
I replaced the plugs with the ones suggested at autohausaz.com. a good place to buy parts cheap. I think bosch platinum plus 4. As to the plug replacement process, see the message in this forum about it there are pictures and all. If you have trouble finding it email me at vesperocco@aol.com and I can send the link. The replacement took about 3 hours because I had a hard time getting the wires off the plugs even though I had a 17 mm open end wrench that I used as a lever to pry them off. You also may break a few of the old plugs in the process and have to pry the top of the plug out of the rubber connector. Its worth it. My mileage is at least 10% better.

I ordered the brake switch as well. just waiting to put it in, but I can tell you that as long as I do not touch the brakes like on a long trip on the turnpike, the lights do not come on. The mechanic at "just answer" also said that if its not a weakening battery, the next thing to do is change out the brake light switch. Cost me $15 to find that answer and you got it free.

Welcome to the world of SL500's.

Just an aside, I really like my car. It sits in the driveway in front of my garaged 1988 jag xjs convertible and I really have lost the urge to drive the jag because of it. I may even have to kick the jag out of the garage.

Rocco

Rocco Vespe

Hey Bones,
You ever been to Mr. Bones on GMD ? I visit LBK for vacation every year and I am scheduled to be there for a week with my honey in August. We stay at the sun and sea near the old holiday inn. you familiar with that area>>
Great beach and great restaurants - Moores stone crab, Mar vista, Bridgetender inn, gulf drive waffle house, beach house,etc.
Rocco

BJonesFL

Keith,
As I said in the other post, the ignition key on/engine running. EXACTLY what happened...My warning light 'trifecta' came on after just having left my tech's shop from a 60K service. I did a u-turn and went back, parked with engine running so as not to possibly erase any codes by powering down. My tech grabbed his OBD scantool, and said, "leave it running until I see which codes are being thrown". He got what he needed in terms of code numbers/letters, then said shut it off. He found two items, battery output and vacuum hose loose.

Since I don't have 1st hand experience with pulling codes with the key in position 3, I'm not going to guess. All I can tell you is the way it worked when my tech checked mine.

Bob

BJonesFL

Yeah Rocco, I live 3miles from Mr. Bones on Anna Maria Island and coincidentally used to live in So Jersey in Ocean City/Somers Point many years ago. Your list of favorites is pretty much the same as mine + the Sandbar, Bonefish Grill, and Mattisons on Manatee River are also good. If you're coming in August, leave the humidity in Jersey, we have enough of our own!

Bob

Rocco Vespe

got a pic of your SL? Maybe I can look for you cruising on GMD. Ill have a rental car unfortunately. I'm in Mt Ephraim, near philly. Lived here 50 years, got three jags and the sl. I think the folks from mr bones are from philly right?
Rocco vesperocco@aol.com

Keith526

Hey Rocco,

Thanks for the info on the spark plugs. I need to see the photos of the plug change so I will look for it today, my email is keithdailey@hotmail.com if yopu have photos.

I looked under the hood at the plugs, they all are very easy to reach so I gave the plug boots a tug, then a pull, then I felt like I was going to break the wire coming from the coil. Why is this wire so hard to remove? Is it a pull and a twist? Or a push then twist/pull? What kind of connection is this? You said use a pry under the rubber boot that could break the plug itself??? Are these plugs not meant to be changed??? I do so want to change them so I’m going to go for it.

My problem is a bit different from yours in that my lights come on a few seconds after start-up then stay on the rest of the drive and the cruise control no longer functions, nothing to do with touching the pedal, Hmmm now I'm getting worried. According to Bob pull the codes with the engine running and the lights on is the way it is done!

Cool thanks Bob! So I’m going to give that a try today! Thanks again guys!!

Keith526

Rocco thanks for the photos! AND GREAT NEWS!!!! the switch fixed the problem!!! They were back ordered because this is a big problem for many MB cars. Still love my car!!!

Rocco Vespe

Keith,
was it hard to replace the switch??
Rocco

Keith526

Hey Rocco,

Sorry it took me so long to reply. Well, I don't know! I asked the parts guy at my repair shop and walked out to my car, reached under the dash for a few minutes then said; "does that answer your question" he did go on to say that most people make the mistake of taking apart the lower dashboard when the switch can be reached from behind the cover? I just drove off grinning from ear to ear. The old switch has a single lever lock that does seem easy if you know where to reach for it. I was personally going to remove the lower part of the dash to have clear access to the switch just about the brake pedal. I know this is not nearly as cool and helpful and what I got for my spark plug job from this group, but it’s all I have.

Rocco Vespe

took my car to dealer and they charged $185 including the switch. Not bad I thought given that I did not want to get under the dash and make more problems plus they verified that that was the problem before they did it. Hey its a $100k car what do you expect???
Rocco

Euri

So I forgot I left my boot ajar and battery dead as a door nail as a result. Ded as in totally dead.
So I charged it up and ad soon as I connected it, both windows went down halfway.
Started the car, the windscreen wiper went bonkas, and the ABS>BAS lights came on and stayed on.
Turned off ignition and restarted it, same thing happened, ie windscreen wipers on again and lights stayed on.
Any ideas how to fix??

Sussex999

You're the man...don't waste time on other strategies.

HLG600

I remember dealing with those warning lights. Glad to hear that sequence resolved the issue for you.