MBWorld.org Forums - SL-Class (R129)

SL/R129 2026 SOUTHERN CALIFORNIA R129 MEET

sushipaste — Sat, 16 May 2026 16:38:39 GMT

MEETUP: 15314 W SUNSET BLVD PACIFIC PALISADES 9:45 AM

CRUISE TO: GREYSTONE MANSION 905 LOMA VISTA DR BEVERLY HILLS 11AM SHARP!

34 CARS CONFIRMED SO FAR! SEE YOU ALL THERE!

SL/R129 Barn Find 500SL Journey

isntgav — Sat, 16 May 2026 03:57:03 GMT

Hey everyone, I just got myself a barn find 1992 500SL with roughly 48k miles that has been sitting for 8 years. I plan to make it my daily once I can get it running. So far I've replaced the sparkplugs, air filters, oil filter, and oil. It starts, briefly. It then dies after a couple seconds of running extremely rough. I've traced it down to a fuel issue, probably fuel filter or pumps if I had to guess. Anyways, that isn't the point of this. I'm new to the SL's, and was wondering what I should look out for on this thing to make it as reliable of a daily as I can. From what I saw during my brief moments of a running engine. ABS and ASR light are on, so I'm looking for tips on how to trace down possible causes if they persist. Thanks guys, and I will update this thread with my progress on getting it running. I assume I will need some help.

SL/R129 Need advice for MB 500SL

elwoodMB — Mon, 11 May 2026 14:23:03 GMT

Hello all! I have a 1990 500SL R129 with 58,000 original miles. Garaged its entire life. Zero rust anywhere. I bought the coupe 3 years ago. I have the hard top. I started replacing the soft top pistons and have done the 4 largest. The 8 small ones left to go. The biggest issue is this. My car starts up absolutely perfectly if it�s been in the garage for a few hours or more. If I drive it, and it�s a warm sunny day, wherever I park it it may sit for an hour and then when I return it won�t start. Sometimes it doesn�t even turn over. It�s just dead. Then after waiting 10-15 minutes of trying, it�ll start up weakly. Then I�ll start it again and it�ll be roaring like brand new. Mechanic said is either a weak ground between the battery and engine or the mechanical engine itself is responding to overheating. Any advice?

SL/R129 Please tell me about Diagnostic Tools.

w209 japan — Mon, 11 May 2026 04:47:35 GMT

Hello everyone. I recently acquired a 1977 SL320. Which diagnostic tool should I choose for this car? Xentry? iCarsoft CR Max? Please advise. I previously owned a C4 Xentry...

SL/R129 Soft top tensioning cable

tonybeecher — Thu, 07 May 2026 00:41:36 GMT

Looking for help. My 2000 SL500 is in the shop having the soft top replaced. They have found that the tensioning cables on both sides are broken. I am trying to find the part number but I am getting conflicting info. I see part 129-770-07-66. Can anyone help me ID the part? Sorry to be such a newbie. TOny

SL/R129 Console sliding door broke

jimbo409 — Wed, 06 May 2026 21:26:36 GMT

My console sliding door is broke , I want to ask where can I get a new one burlwood and how hard to install it

SL/R129 keyless/fob RF antenna or module?

SmokeSilverSL — Wed, 06 May 2026 05:47:56 GMT

Trying to get a fob to work with the new-to-us SL500, 1998.

We have one switchblade key that came with the car. Using the physical key in the door lock unlocks/locks the car and trunk, and starts the car... no problem there. Transponder seems to work just fine. The fob itself was DOA when we got it, and I suspected it just needed the battery. Replaced that and got the battery-check light to flash on the fob when pressing lock/unlock. That's as far as I got. No amount of trying to sync the fob to the car has been successful. Tried various procedures outlined in forums, as well as the one in the manual. No joy.

Checked the fob on a cheapo key fob analyzer from Amazon, and indeed the key is putting out a 315Mhz RF signal and IR as well.
Is there an RF antenna somewhere for the keyless entry/fob signal that I should check? I was told there may be multiple antennas and if any one of the fails it causes the system to fail? Not sure whether that's right. I know the older cars had the IR system in the rearview mirror, not sure about the later cars. All the fuses seem fine.

SL/R129 Help With Identifying Unknown Part!

farufii — Tue, 05 May 2026 00:43:51 GMT

Hello all, sorry for this being my first post!
This afternoon after returning home, I noticed this part on the ground underneath where I usually park my SL. I�ve been puzzled as aside from some very slight steering differences (which I very well could be hallucinating in my attempt to notice tiny changes, as I frequently do) I haven�t felt anything odd with the car today. I daily drive it so I�d like to think I have a pretty good idea how things feel day-to-day. It�s clearly sheared off on one end, meaning whatever other piece of it has the part number. Any help pointing me in the right direction would be very much appreciated!

Edit: car is a �98 SL500 with 104k miles. forgot to specify that, in case it helps

SL/R129 Work Shop Manuals for 500SL R129

tedbenz70 — Fri, 01 May 2026 19:06:50 GMT

My car is a 1991 500SL R129.

Many years and MANY computers ago, I purchased the R129 STAR Class Service Manual Library discs. As I said, that was many computers and operating systems ago. Now I have a problem with the car and I cannot get these manuals to install, so I am flying blind.

I see there is a lot of on-line services for manuals now. Are any of them any good? What is everybody using?

Thank you.

SL/R129 LOW BEAM HEADLAMPS NOT WORKING

tedbenz70 — Fri, 01 May 2026 19:02:42 GMT

This started a while back. First one low beam goes out and then the other. At first, they would come back on if I let the car sit a couple days. Now the low beams are out all the time.

The high beams work fine.

I cleaned fuse contacts. I installed new fuses. No change. Using a test light, I found there is no power to the low beam fuses.

Just to be 100% sure, I checked the headlamps, their wiring and the ground connections. All seems to be in order.

Then I put a jumper between the fuse for the high beam and the fuse for each low beam ... the low beams do work and do not blow a fuse. This indicates to me that from the fuse box to the headlamps, everything is in order. The problem is from the fuse box back to whatever control units, relays and switches there are.

As a part that commonly goes bad, I installed a new headlight switch in the dash. No change.

I replaced the lamp control module (129 542 01 32) with a used unit. This is the lamp control module (129 542 01 32) located to the rear of the main fuse box. No Change.

I removed the cover from the lamp control module (129 542 01 32) that was in the car originally. This module is a solid state and NOT a mechanical (electro-magnet) device. I have no way to test these units and have not been able to locate a new one.

Does anyone have a wire diagram for the light circuit? Many years (and computers) ago, I purchased the R129 STAR Class Service Manual Library discs. As I said, that was many computers and operating systems ago. I cannot get these manuals to install now, so I am flying blind.

Does anyone test and rebuild these lamp control modules (129 542 01 32)?

Does anyone know if the high beam switch in the steering column is known to fail?

Are there other components in the circuit that I am missing?

Although it's been suggested, I cannot find a reference to an "exterior lamp relay" ... or it's location. If there is such a thing, Could someone tell me where it is located?

SL/R129 RENNtech is Back for the R129!

mahunt — Thu, 30 Apr 2026 15:21:53 GMT

I just got an email from the fine folks at RENNtech and they are offering some of their past upgrades for both the V8 and V12 R129 cars.

Now the folks that missed out can party like it's 1999!

https://store.renntechmercedes.com/c...-129-1990-2002

I didn't see the resonator eliminator, but everything else seems to be there, even the heim joint suspension stuff (which I recommend).

Party on.

SL/R129 ELECTRICAL GREMLINS- need help please

Miawallace — Wed, 29 Apr 2026 17:32:18 GMT

Hey guys,

I have a 1999 R129-trying my best to chase some electrical gremlins. Would appreciate any and all input

Issue:
no power > windows, latches, seat movement

Windows intermittently work while driving.
latch switch works once this week and hasn�t worked again. Switch lights up and gets power on ignition.

i have checked fuses and have 12v going to windows on #1&2 fuses

SL/R129 Outer Race Bearing?

FloridaMan69 — Sat, 25 Apr 2026 22:47:21 GMT

Hello everybody,

Does anybody have any tricks for getting bearings out? I feel like I've tried everything - the slide hammer, screwdriver, bearing pullers, heating it up. I cannot get this thing out. I feel like I've even marred up the hub a bit in the process and at this point I'm wondering if it'd be easier to just get a damn hub.

Thanks in advance

SL/R129 Soft Top Inop after Battery Change

Breezing — Sat, 25 Apr 2026 12:05:56 GMT

Hi All, I have a '99 SL500 with 47k miles. Everything worked beautifully until I had to replace the car's battery. After replacing the vehicle battery, my soft top is now inoperative, throwing a fault code "fault short circuit to positive limit switch signal illogical". I am able to clear the fault using the diagnostic tool, with it showing "pass" afterwards, but as soon as I try to raise the soft top, it throws the code again. The windows and rollbar are all operating fine. Any suggestions are appreciated. Thank you in advance.

SL/R129 rear window replaced

jimbo409 — Thu, 23 Apr 2026 22:40:33 GMT

Does anyone know if the reae plastic windows can be replaced or do I need to have a new top installed. also an estimate of the cost for both items. I live in chicago and dos anyone know of a good shop to do this kind of work