Car no start

[elau]

Help!!! I am pulling all my hair out. This is the second weekend the SL won't start. Turn the key, all lights come on, but the engine won't turn. Not even a click. The last time it happened, I wiggled all the fuses and the car started right up. Not today. I even changed out some of the fuses, but still no start. Where else should I look?

Any suggestions?

[450slcguy]

I doubt wiggling the fuses has anything to do with it not starting. For starters, Check the battery for charge and the battery terminals for corrosion, make sure the cables are clamped on tightly to the posts. Could be a dozen other things, but check the above first.

[Strife]

After doing all of the above things, the ignition switch could be bad. This does happen. Jiggle the key. Perhaps the transmission neutral safety switch, but I'm less familiar with that. Jiggle the shifter.

[elau]

Originally Posted by 450slcguy

I doubt wiggling the fuses has anything to do with it not starting. For starters, Check the battery for charge and the battery terminals for corrosion, make sure the cables are clamped on tightly to the posts. Could be a dozen other things, but check the above first.

Battery is good. No loose cable.

[elau]

Originally Posted by Strife

After doing all of the above things, the ignition switch could be bad. This does happen. Jiggle the key. Perhaps the transmission neutral safety switch, but I'm less familiar with that. Jiggle the shifter.

Tried to start the car in N just in case it was the neutral safety switch.

[LeaUK]

elau

I'm sure we've been here before - I put money on your ignition barrel!

Mine started failing with identical symptoms then gradually things started to decline with the instrument panel suddenly flashing etc..

This works for me when mine fails to start:

1. Hold the ignition switch in pos 3 (start) and move the steering wheel fully down in/out and see if she starts.

This I know sounds weird but it has worked for several and is a known technique.

I went round the same loop around 6 months ago checking, park switch, ignition lock-out switch, igninition imobilisor relay, brake pedal - etc, etc and now I know it's the ignition barrel - this is a VERY common replacement part at around 10 years.

I have a new one sitting here (cost only 45GBP), to go in at the weekend

Lea

[elau]

LeaUK,
What do you mean by ignition barrel? Is it the same as ignition switch? Do you have a part number so I can order one from the parts store online. Thanks.

[Bondavi]

If you go to www.*************** and look under your car's Ignition Parts section, you will find separate components, including the switch. That parts store is VERY reasonably priced, and they use German suppliers in addition to Mercedes OEM parts. Hope that helps!

[elau]

Assuming it is the ignition switch, how many hours will it take to do a job like that? Is it even a DIY project?

I called an indie in town and he quoted the labor rate at $95/hour That's more than the dealer!! He said the entire job takes 4 hours.

[Richard Wooldridge]

Hi there,
If you have a voltmeter or test lamp, isolating the problem should only take a few minutes, assuming you can connect it to the appropriate points without too much pain. I would first test for +12VDC at the main starter terminal, make sure it's there using the engine as the ground reference. If it's there, turn the key to the start position and see if it goes away... Also measure for zero ohms between the negative terminal of the battery and the vehicle's frame. Then clip the meter on the start terminal of the starter solenoid and see what happens when you turn the key. If there's no change, follow the line back to the shifter interlock and see what you have there. The next item is the switch itself. You should be able to isolate this problem in no time at all!!
*HINT* I use a needle passed through the insulation into the wire if it's too hard to get to the terminal itself, works great and makes for less contortions trying to get to a test point. Use Pliers to insert the needle.
On my old '75 280C the starter bendix used to stick in the flywheel teeth, would cause a similar symptom to yours... You can try rotating the engine slightly by turning at the belt area to see if that is the problem...

[LeaUK]

The barrel describes the complete 2 part assembly including the tumbler and the switch. The tumbler is the mechanical locking mechanism which accepts only your key and the switch fits onto the rear of the tumbler that controls the electrical contacts.

You probably only need the switch (although I bought both to improve the feel too).

Part Number Description Cost

129 545 02 04 Switch 55GBP
140 462 00 79 Tumbler 85 GBP - notice it's shared across the W140 range

I consider it's a DIY job but you need two tools:

A piece of 2mm brazing rod or similar and part number: 210589000700
'Claw-type wrench' for the trim ring removal - or maybe a small pair of pliers will remove yours it all depends on how tight the ring is.

Looks like the job will take 2 hours. I have the full instructions and a video showing he removal process should you wish. I should be undertaking it this weekend but I've been saying that for several weeks now!

Lea

[elau]

LeaUK,
Thanks for the info. Yes, I found lot of your threads about the ignition switch topics after I fired out this e-mail.

I would like to have the instruction and video if you have them handy. Thanks again for all the information and assistance.

[Captain Scott]

I had similar trouble with my 74 SL after pulling the seats and suspected my ignition switch, too. The fuel pump would power up and everything sounded good except the solenoid would not kick. After trying just about everything including bypassing the starter switch all together (which I ran on for a month!) the culprit ended as a failed starter interlock relay. If you have the electrical drawings, you can pull the relay plug and figure out which pins to jump to see if that does it. It is a 1.5 inch relay box with the usual bosch plug right above the brake pedal. Of course, you could jump power directly to the terminal block that feeds the solenoid as a test if you know where it is, too. Mine is on the right side below the window washer fluid resevoir.

Before spending money, at least test this one area.

S

[elau]

OK, this is what I noticed. I have no map lights, they will not turn on. However, the foot and door-sill lights are on.

I decided to check the battery, and each cell requires a little more than 240 cc of water. I topped off each cell and put a trickle charger on the battery this morning. The battery was purchased on 5/19/01, and the car is driven less than 3K miles a year. Hope that is the culprit and not something expensive gadget.

Will keep you all posted.