no_clue

Can anyone show me where I can tap a 12V line in the engine compartment, that is directly feed from battery w/out going through fuse/ resistor or ECU?
(E320)

thanks,

raymond g-

hey, check the engine compartment. i believe your car and mine (for one)
has terminal points right above the left wheel well...close to the firewall.
the purpose was to allow booster cables w/o having to route under the
rear seat. (presuming your battery is still under the seat).

plastic cap swings open and should have a big "+". ground would be clean and effective chassis ground.

New E350W4

Hmmmm?
As stated, I thought there are terminals onder the hood but, just looked in the owners manual and it doesn't say BOO about this, only in the trunk. In fact, that's where they refer you when jumping the battery(or someone elses)

no_clue

thanks Ray; ( battery in the trunk now )
for your curiosity, I am installing a relay to HID ballast.
I don't want to have the ECU program to "xenon present", just in case, I want my regular bulb back on.

health services

The relay may not show enough resistance to the computer and may still set off the code. You may need a resistor in series to the relay.

no_clue

Now I am confused even more....
The HID kit I installed works perfectly when engine is NOT on.
When I started the engine, both flickers like crazy!!!!!

I suspect the ECU is NOT providing enough current, hence I try to tap the 12V directly to the ballast.

KosherBenz

you need to go to the dealer and acitivate "Xenon present" in their computer.

no_clue

I did mentioned that I don't want to have the ECU program to "xenon present", just in case, I want my regular bulb back on.

KosherBenz

then just go back to the dealer to have them deactivate it.

amdeutsch

I'm not 100% on this but I believe that the setting will have no effect on using regular bulbs. I believe it is designed to detect low or no current draw.

raymond g-

ahhhh.....seems now that the under-hood positive terminal was discontinued
after they moved the battery from under-seat.....back into the trunk. so
you're right. no more under the hood access. sorry for the misdirect.

KosherBenz

i have a small battery under the air cabin filter.

amdeutsch

Yup, the E has 2 of them; one small, one big, one front, one back.

raymond g-

yeah...i'm getting mixed up and got redirected towards jump starting the car.
so the rear battery should *only* be used for jumpstarting (whereas on my
99 E320, the engine compartment terminal can be used to jump). N_C's
query was simply to tap for power so that's different...and I s'pose, can
consider that front battery.

btw...what does front/smaller battery handle? misc electronics, no doubt?

SAguirre

If you have the daylight running lights on, then the computer lowers the voltage to the non-xenon lights (H7) so that they last longer. If you have the actual setting changed in the computer this will not happen. This is one of the many reasons why the computer needs to be set to accept the 35W draw of a xenon light instead of the 55W draw of the H7 bulb. Xenon lights are not dimmed if you use the "constant" setting on the daylight running lights. So if you do set a resistor in parallel, and you have daylight running lights on you will still have problems.

Hope this helps a bit more.

Steve

no_clue

I believe small front battery is for ECU and remote control?

Also I still don't know where the heck is the 12V terminal in the engine compartment!!!!!

raymond g-

i dont think there is one, R. I haven't seen any reference to a POS terminal
under the hood for jump starting in the W211 where the battery is in the trunk.
i searched through quite a number of PDF manuals and it is absent any mention
of this ....versus, say in the W210 manuals with battery under the rear seat.

here are two examples.....

no_clue

thanks Ray.....

this is really pissed me off though.
I will NOT let dealer to program my ECU yet.

I will find another way which suggest by fellow member Allen.
(capacitor, here I come!!!!!!!!! )

tlluberes

I think in Starter you have 12 volts + permanently.I think starter are in Engine compartment

tlluberes

For my car, i used 12 volts from auxiliary battery in engine for feed relay for my HID.Not Problem. This Red wire came from trunk battery for to be charged.
This front battery is for brake pump.
Not problem. In The regular H7 socket i used regulator canbus. Ebay $ 10.00. Just for avoid warning light in dash.

starbrite

Uhmmm....you do realize that this thread is 6 years old, right?

PDX4matic

I don't care how old this thread is, it solved my problem of finding a 12v constant under the hood! Thanks for the help, 3 years or 30 years!

nivram13

Fuse tap into cig lighter fuse #54 on front SAM switched feed.