280sl r129

[Ajmerc]

Hi i have an sl r129 with a flat battery. Unfortunately the boot will not open, the barrel just spins round when i try and unlock.
I cant see anywhere in the engine bay where there is a positive terminal to jump start or charge.
Any tips ??

 

[E55BOF]

If it's the same as a 1994 (I think it was...) 500 the main fuse box is under the bonnet at the back of the engine bay on the driver's side (if it's rhd), and the fuses are the old torpedo type with the actual fuse 'wire' on the outside. You can attach a battery charger positive lead crocodile clip to a permanent live fuse, and the nagative lead to a good earth. You'll get enough juice in the battery to open the boot.

Alternatively, if you jack up the car you can get in underneath the engine bay and attach the positive lead to the alternator terminal direct from the battery, and the negative lead to a good earth. Same outcome.

I hope this helps.

 

[Ajmerc]

Thankyou ill try this today

 

[Deefor62]

Hi i have an sl r129 with a flat battery. Unfortunately the boot will not open, the barrel just spins round when i try and unlock.
I cant see anywhere in the engine bay where there is a positive terminal to jump start or charge.
Any tips ??

I had the same issue, again without being able to manually unlock the boot. I found a positive point in the relay box on the passenger side (rhd car) under the bulkhead. If you remove the large cover - approx 5 screws, there's a junction box in there next to the OVP relay. If you flip up the cover to the junction box with the large wires going into it, you will see a terminal with the nut/bolt painted red. I used a battery booster pack, and simply attached a positive lead onto that, and a negative lead onto the exhaust manifold. This enabled me to open the boot using the central locking, and I was then able to put the battery on charge.
I also discovered another positive junction under the carpet in the front of the passenger footwell. If you pull the carpet bacl (there's a handle attachment on the top of the carpet under the glove box), and then remove the plastic panel under the carpet, you will see a similarly red painted nut/bolt junction, which in my case, was to the left of the amplifier/crossover. Hope this helps if anyone else has a similar problem

 

[Ajmerc]

I had this same issue,i put a charger to the alternator and left it fot a couple of days, changed the battery on the key...the battery charged enough to open the central locking

 

[BTB 500]

As an aside a flat battery can sometimes cause issues on the R129. It resulted in spurious fault codes relating to the windows being logged on mine, which blocked the roof from operating. These had to be cleared by an MB specialist using STAR diagnostics, after which all was fine. So keeping it on a maintenance charger is a good idea if at all possible (i.e. you have mains power available). This has other benefits - the battery in mine is nearly 20 years old now, and still going strong!

 

[MD5]

Sometimes a few squirts of WD40 in the lock barrel, then a bit of a jiggle around can help with using the key manually again.