'88 300 SL a couple of electrical problems

[richo]

I've got an '88 300 SL (107) and I have a couple of electrical problems that I wonder if someone can help me with.

The first is the indicators and hazard lights are a bit faulty. Generally they work fine but occasionally the indicators won't work. I then flick the hazard switch on and off (often there's a crackling/rattling sound when I do this) and this seems to correct it. At the moment though when the hazards are turned on only one side of indicators works (it randomly alternates between which side). Any suggestions? I'm guessing it's the relay, if that's the case anyone know where it is?

The next problem is less urgent but I'd like to fix it. The cruise control doesn't work and I don't know where to begin in solving the problem.

Thanks for your help

 

[jolly]

Hi richo i to have a similar problem and would be greatfull if you find a cure would you please let me know thanks jolly

 

[television]

I would clean the stalk with a good non drying switch cleaner first

 

[Myros]

the cruise control will give you a lot of trouble

It's usually the amplifier/brain thing that goes. If you are good at electronics, I can point you at an article on one of the german SL club sites that shows you how to repair them. If you are like me, you'll sit there wishing your german was better, and that you knew a transistor from a diode from a valve.
You can get replacements from breakers yards. Any brain from a similar vintage 300 model of any description, w124, w126, whatever, as long as you are looking at the same m103 engine type. Of course, they don't come cheap, they never do. there is always e-bay, but you have to know your compatible part nos. Search on here for cruise control, and somewhere there is a reference to an american site which has compatible nos.

 

[richo]

It's usually the amplifier/brain thing that goes. If you are good at electronics, I can point you at an article on one of the german SL club sites that shows you how to repair them. If you are like me, you'll sit there wishing your german was better, and that you knew a transistor from a diode from a valve.
You can get replacements from breakers yards. Any brain from a similar vintage 300 model of any description, w124, w126, whatever, as long as you are looking at the same m103 engine type. Of course, they don't come cheap, they never do. there is always e-bay, but you have to know your compatible part nos. Search on here for cruise control, and somewhere there is a reference to an american site which has compatible nos.

Myros - please could you post the link to how to repair the amp. My sister's got a degree in German so I might call in a favour. I doubt I'll have the electronics skills but a couple of the guys in our office have electronics degrees so I might try and call in a favour there too. Many thanks.

 

[Myros]

Richo, here you go

if your sister twigs it for you, I'd love a copy of her instructions, and I might have a go at mine.

http://www.sternzeit-107.de/modules.php?name=News&file=article&sid=297&mode=&order=0&thold=0

 

[David Pemberton]

Hello Richo

Re hazards and indicators. On my car I can partly replicate your problem if I turn on my hazard lights and then don't press the switch fully when I turn them off. After that my indicators won't work until I make sure the hazard switch is off properly.

When I re-wired my car alarm I remember that all the indicator wiring is routed through the hazard switch. I suggest that you take the hazard switch out and clean the connector on the back (you have to remove the wood trim of the central console which from memory isn't too hard and you start by taking out the ashtray - it's all screws and at no point do you have to force anything so if it is stuck don't lever it or you will just hear splintering real wood - keep looking for more fastening screws).

Best wishes

David

 

[wireman]

The hazard switch is dirty, dust and the like gets into it around the button edges and gets in the contact grease within the switch, this then holds the contacts apart until is is dislodged.
This is common in 190s that belong the smokers (those who use ash trays) spillage from the tray gets into the switch.
On some older switches it is possible to take them to bits and clean off the contacts, but beware of spring loaded innards that fly away as you open the switch up.

 

[richo]

thanks for the advice on the hazard switch - cleaned and now working fine. I cleaned the driver heated seat switch while I was at it and that now works too.

I'm having trouble undoing the steering wheel at the moment so can't get at the cruise control lever to check its operation

 

[Myros]

I had fun with the wheel the first time as well

http://www.detali.ru/cat/oem_mb2.as...&L=765.707&CT=F&cat=574&SID=46&SGR=105&SGN=03

Get down to the dealers and order part no 17 from this diagram. They describe it as a screw, but you know it's bigger than that. Make sure they understand it's the steering wheel retaining bolt. Only a couple of quid. You wil probably chew it to bits getting it off. I ended up having to drill successively deeper and narrower into it, and use a bolt extractor to get it off. The bolt extractor is still intimately involved with the original bolt. Your torque for retightening the bolt is 80Nm. I suggest you use a sump plug or similar with a big ratchet or t-bar or better still a torque wrench, as you'll never get the force you need with an allen key. Be careful to have everything as square as you can, and the wheel braced and tied off so it can't turn, or else you might injure yourself or the steering lock or your windscreen or anything else in the way. If it doesn't work, get to a friendly welders and have them mig a 22mm nut onto it dead centre and then just take it off "normally"

 

[richo]

thanks Myros.

I bought myself a socket with a allen key head the right size. That and a fair bit of force did for the fella.

Squirted lots of switch cleaner on the cruise control switch but no joy so I guess it's one of the more complicated things i.e. the electronics or the mechanical actuation.

Next step for me is to check the ECU I think.