So I know this is my first post, sorry for going straight to an electrical tech question.

Let me start by saying I did not cause this issue!. So my cousin has a 02 s500 that had a dead battery. He attempted to replace it but he purchased one with the terminals opposite where they normally are. Yup he connected the battery with the terminals reversed, now there is all kinds of issues, and since I am the only mechanic in the family(Ford trained engine repair tech) I get to attempt to fix it.

The issues it has now is that it is slammed all the way to the ground(equipped with air suspension), and also the alt will not charge. I found a blown fuse for the air suspension that i have replaced, it was under the rear seat on passenger side fuse panel and I also found a blown fuse on the amplifier for the sound system. From what i can tell there aren't any other fuses that blew. Replacing the fuse did nothing for the air ride except light up the button on the dash. I have yet to pull codes on it. Is there a way to test the motor or bypass to force it to turn on to see if it still works? I assume i could jump the relay to attempt to power the motor right? I am able to jump start the vehicle and it will run fine, but when i disconnect the jumper wires, the car dies.

Any help would be greatly appreciated. Sorry for the somewhat long winded story.

-Tony

 

if you are lucky, some of the pre-fuses blew; some up to the lefyt of the battery behind the covering, others under the font passenger floor mat.

You need to do a lot of searching/reading on this and the other (Benzworld.org) forum.

Good luck!

 

I assume that the pre fuses are in line and not part of the fuse panels, correct? Ill take a look tomorrow and ill try to pull codes for the air suspension also.

 

This is why idiots shouldn't work on Mercedes.

Take this as a lesson, when working on these cars: do not be an idiot.

 

Yet another hateful comment...

 

Getting the terminals wrong can happen to anyone on any brand car

 

I totally agree, even the most experienced people make mistakes. What is that big fuse under the passenger side front called? I would certainly check that out.

 

It can, but it happens more often to idiots.

 

Tony,

This statement is, I think, very important. If by using an external battery to run the engine, the main engine management circuits must be acceptable. You're getting fuel and air in reasonably correct proportions. Maybe not tuned, but at least workable. So why does removing the external battery make the engine stop? Either the installed battery is completely shot, or the installed battery is not fully charged because the engine charging circuit is blown. I would start with that.

ibeforreal is (I think) referring to the fusible link. And yes, it is worth investigating as it's usually considered the last ditch fail-safe for electrical overload. Not sure, but maybe it is a part of the charging circuit. I don't have the schematics handy. Focus on the 'why' the engine won't stay running unless in an external battery and I think you will be home-free. Good luck!

Cheers,
Jeffr

 

Ouch! Fuses may blow but remember fuses never protect from reverse polarity. You in for big repairs mate. I am busy repairing such a car now too that the cust fitted battery incorrectly. Air suspension collapsed. Esp lamp on. Not charging. No Parktronic. No AC blower. First thing you will find is a blown 150 amp fuse under right side footwell. That will sort charging problem out. Next replace both from and rear SAM modules. All output stages for dampening valves in airmatic control unit were fried. Climate control unit output for blower damaged. Replace blower regulator. ESP fault internal error. Good luck.

 

How do you jump start the car ? Using another car or just a portable jump pack ?

I bet there's damage to The cars battery cables , ground strap or the battery itself had failed internally .
Put a brand new battery in the car then diagnose further .

 

Sounds like the same problem as im having. I checked the 150 amp fuse like you said and it is bad. Ill replace it tomorrow and see if that fixes the charging isssue. Thanks for the advice!

 

I jumped it using another car. The battery still takes a charge its just that the charging system is not charging. The main fat cable is ok but i havent checked the other cables yet.

 

I checked the fuseable link in the trunk and that was ok, but the one on the passenger front floor was blown. Im optimistic that will fix the charging system issue.

 

Im having a hard time locating the fuse by itself. It seems like the dealer will only sell the whole fuse box. Its not too expensive but if i can get just the fuse i need that would be better. Does anyone know where i can get the 150a fuse by itself?

 

As strange as it may sound, check out the local wrecking yards that have a selection of MB's. The nice thing about a fuse is it's easy to test, and it either works or it doesn't. I'm sure Potomac would have it, but their on the East Coast. You can Google 'em for web and contact info. FleaBay maybe?
Cheers,
Jeff