Trying to help a guy out in a nearby town and rode down to check it out this morning. Seems he tried to use a booster pack to start his S500. Now when you follow the procedure in the manual for jump starting it does nothing but blow the yellow fuse as pointed out in the picture. Does anyone know what circuit this fuse is protecting? Also, is 20amp the proper rating. We could not find the fuse chart for the car. Any wiring schematic or fuse identifier would be appreciated. I'm thinking this is an over voltage protection relay board that the fuse is plugged into. Does anyone know the proper name for it?

tia

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Jim

It's the front pre-fuse F32. Fuse #9 (20A) powers the load side of the starter relay.

Thanks
He musta fried that circuit. I'll start by troubleshooting it. I have got to get off the pocketbook and pick up an SDS system with WIS, etc... to make this stuff easier (or will it). I suspect he probably kept the booster pack hooked up and cranked the heck outa the starter. Won't be surprised to find a burned up starter.

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Jim

Another question. Has anyone seen what all is damaged if someone was to hook up the booster backwards when they tried to start it? Talking to the tow truck driver the owner tried to use a booster on it and I'm not sure the guy knew which way to hook it up. The book clearly says NOT to use one of those booster packs on the car during start up. Anyones experience in seeing all the damage done during these scenarios would be appreciated.

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Jim

I need to ask this another way.

Without the SDS Star system would I stand a snowballs chance in the Mojave to repair this car?

The only thing I could do right now would be to inspect all the wiring associated with the starter. I did come up with a wiring schematic for the car but it is kinda cumbersome. Anyone know the number assigned to the starter relay box? Where is it located on the car?

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Jim

That's a good question. I'm afraid I can't answer it though, because I've never tried (and wouldn't want to) to diagnose any modern MB without SDS.

Thanks, it would be interesting to get the car into the shop but I think I'm going to pass on it until I get the SDS system I need. I suspect he did a pretty good job frying some stuff in there which I doubt is going to be very economical to resolve.

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Jim

The owner wants me to at least look over the car to see if there is anything obvious. I'm going to have it hauled to the shop where I can work inside. Anyway, I imagine I'll be picking up the necessary computer and such here over the next couple weeks.

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Jim

Got the car in the shop and am just looking around to see if anything is obvious. So far the only thing I've found is the end of the battery blown out (picture attached).

I've got the AutoLogic sales rep coming by this week to give me a free "demo" and will try it on this car.

Is the pre-fuse box supposed to take all the damage from a booster box connected backward? Is there a way to open it up and inspect it? Which module is the starter relay located in and where is it?

Note in the first picture how someone had put the red warning tag over the - side of the battery terminal. I suspect this is what threw the owner off when he tried to jump it.

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Jim

sounds like a nightmare. would hate to have a brand new car like the s550 and this happen.

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http://www.pbase.com/image/21611314.jpg

Jim, the owner of that 2007 S550 should call for help when he has a problem because apparently he knows nothing about cars, or at least MB automobiles. In the picture of the failed battery the positive terminal is clearly marked with a "+". How do you hook up a booster pack backwards? I suspect the booster pack has visible warning labels about the correct cable orientation.

Good luck sorting out that problem. If I were you I would have the car towed to the nearest MB dealer, and have the owner bite the bullet. Consider it an expensive "learning experience".

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Fred Hoelzle

Thanks Ferdman, unfortunately, that + terminal tag had actually been installed over the - terminal of the battery. It was evident when I got there to take a look at it because obviously the - cable is bolted to the steel of the car in close proximity to the battery.

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Jim

Jim, the "+" is pressed/stamped into the top of the battery and clearly shows in the thumbnail picture you attached to Post #9. Any knowledgeable MB owner should know that the negative terminal is ground.

I guess your friend is one of those people who reads the Owner's Manual after suffering from a self-induced problem. My first instinct would be that using a booster would be OK if connected properly, but I would have checked the Owner's Manual before assuming anything.

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Fred Hoelzle

Doesn't the owner have any warranty left? Its only 4 model years old, guess he didn't spring for the extended!

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

The owner is originally from Vietnam and his english is marginal. I have not found anything obvious. I do plan on waiting for the AutoLogic rep to come by and hook it up to see what it says. Otherwise, I'll advise the owner to have it hauled up to the dealer (80 miles away). I'm still going to be curious what exactly they end up finding. It would be interesting to see if MB designed it so that when this happens it would ONLY take out the pre-fuse. I'm thinking it may well be something internal to the pre fuse that may have gone bad but I was unable to open it up to inspect it.

I did find a bare spot on the small wire going to the starter solenoid. Taped it up and there was no difference.

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Jim