Process to unhook ground terminal to work on car?
Thread Starter
Junior Member
Joined: Jun 2020
Posts: 33
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From: Fairfax County, VA
2008 R320, 2002 E320
Process to unhook ground terminal to work on car?
I hate to ask what I think is a dumb question, but the W251 battery access is so needlessly complicated that I want to double check on this before attempting my trailer wiring install.
What are the proper steps to unhook and then reconnect power from the vehicle to work on electrical issues? It looks like I can get to the negative terminal of the main battery by pulling back the carpet between the door and the B-pillar of the passenger seat - no seat removal required, and it doesn't look like you can get to it from the front footwell. The service manuals I've got say you have to go through basic reprogramming after, which is fine, but then it says to clear out fault codes in STAR, which is not fine. A colleague warned me that if you don't have the steering wheel dead-on straight, you'll have steering angle sensor errors and will need to go to the shop to get this fixed. Is this true? Do I need to unhook the auxiliary battery as well? I'm guessing no, but I don't know.
If anyone has successfully unhooked power from the battery without fully removing the battery, I'd very much like to know best practices here, before I heap a bunch of trouble on myself.
What are the proper steps to unhook and then reconnect power from the vehicle to work on electrical issues? It looks like I can get to the negative terminal of the main battery by pulling back the carpet between the door and the B-pillar of the passenger seat - no seat removal required, and it doesn't look like you can get to it from the front footwell. The service manuals I've got say you have to go through basic reprogramming after, which is fine, but then it says to clear out fault codes in STAR, which is not fine. A colleague warned me that if you don't have the steering wheel dead-on straight, you'll have steering angle sensor errors and will need to go to the shop to get this fixed. Is this true? Do I need to unhook the auxiliary battery as well? I'm guessing no, but I don't know.
If anyone has successfully unhooked power from the battery without fully removing the battery, I'd very much like to know best practices here, before I heap a bunch of trouble on myself.
