2002 S500 electrical mishap :(
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
You need to do a lot of searching/reading on this and the other (Benzworld.org) forum.
Good luck!
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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
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 .
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
Cheers,
Jeff









