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1996 SL500
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Discussion Starter #1
High all I'm looking for suggestions. 1996 sl 500 80k on the clock . The condition I'm about to describe is intermittent. Lately it has become more common. Symptoms; turn key engine starts. Idle is erratic. push accelerator to the floor no change in engine speed. ASR and ESP lights are on. Switch off the engine. Restart the engine it runs and drives fine. No warning lights of any kind. If the engine is warm and I start it and get the erratic idle I can get the symptoms to disappear by turning the key toward off and quickly back to run. The throttle body was replaced 8k ago by the PO. The wiring harness looks good. Any ideas?
 

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'03 SL500, '03 SL55, '97 SL320, (2) '91 300SL, (2) '91 500SL, '00 S500 -- all for sale
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ASR and ESP lights are on.
Read diagnostic codes for these two systems and you should learn the cause of your problem. You'll need a $250 Chinese-cloned Star Diagnosis System (SDS) or the like.
 

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R129 500 SL 1991
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950 Posts
Did you mean ASR and ABS lights are on? Sounds very much like it’s the ignition switch. My experience is that the ignition switches last around 40k miles before that start to play up. Search the forum for Albert’s posts for tips on diagnosis. @aam

I am not sure that STAR would pick up an intermittent ignition switch problem. You would be looking for low current supply to the EZL, and this module does not provide this feedback as far as I am aware. Code readers or STAR (if you have access to it) would be useful to eliminate other possibilities, but none are springing to mind.

@aam wrote about a method of testing the supply to terminal 15 of the EZL with a test light bulb. Another suggested checking the voltage at the fuses with the ignition on. Any variation potentially points to the ignition switch.
 

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1996 SL500
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5 Posts
Discussion Starter #6
I have decided to replace the ignition switch. Removed the old one MB1405450004 it has twelve pins. All I can find on line are 14pins. Called MB dealer they say the part # is wrong. They used my vin to find what they say should be correct. If I order through them and it's wrong. I have to eat it. Anyone have a source for MB1405450004?
 

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R129 500 SL 1991
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950 Posts
There was a thread on Benzworld about a year ago where the OP bought an ignition switch from MB USA Classic centre. I think he had similar issue. I will try to find it.

In meantime here is another thread: -

 

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R129 500 SL 1991
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950 Posts
Here’s the thread: -

 

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1996 SL500
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Discussion Starter #9
Thanks for the info rob. I bought a 14 pin switch same one the dealer listed. I bought it from Wades foreign auto parts here in town. The guy has been in business over 50 years. I told him about my situation and without hesitation said the 14 pin would work. You can't beat experience. I installed the new switch and it works fine. However it didn't fix the original problem. I did make an error in my first post . It should have read the ASR and EPC lights were on. I did another search based on that and found a couple of old threads where the guys had experienced the exact same symptoms I have. They seem to have come to the conclusion that the problem stemmed from a leaking electrical sleeve on the transmission, however they stopped posting without saying for sure. I changed the sleeve about 7k ago, but I'm going to check it anyway. If I post again on this I think it might be simpler to start a new thread with a more appropriate heading. Thanks again for the help.
 
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