Battery disconnect and reconnect order.

[T8WBN]

Good morning.

I need to replace my light ballast on my 2004 SL350 R230.

I have read mixed messages about disconnecting the batteries in a set order, leaving a positive connected, not disconnecting the starter battery at the front, and there seems to be no firm method. I want to avoid at all costs having to reset any systems if it can be avoided... must i disconnect the battery if I am disconnecting the whole light assembly anyway when I have the front of the car apart?

Is anyone able to offer some guidance... hoping to start this repair ASAP.

Thank you and regards, Will

 

[00slk]

Basically, disconnecting the battery earth helps to avoid accidental shorting out when working on electrics. Lights ballasts give out many volts, you don't want a jolt from those.

 

[T8WBN]

So do you reckon disconnect the negative on both batteries? Or just the boot batt?

 

[LostKiwi]

If you disconnect the rear battery you will need to reset windows and steering angle sensor. Neither are a big deal. If you're only doing lights make sure key is well away from car, headlights set off and remove the lights without disconnecting but be very careful.

 

[T8WBN]

If you disconnect the rear battery you will need to reset windows and steering angle sensor. Neither are a big deal. If you're only doing lights make sure key is well away from car, headlights set off and remove the lights without disconnecting but be very careful.

OK thank you.

As its a 2004, it doesn't have keyless entry/go, however I agree, prevention is better than cure just in case.

Understood regarding the windows and steering, my worry was transmission and some of the other things like command and electric roof. However i suppose the priority regardless is getting the headlight fixed.

Cheers!