Low-beam bad, what voltage should be at (cut) ballast wires?
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2005 C320 4matic
Low-beam bad, what voltage should be at (cut) ballast wires?
Hi, I just got a 2005 C320 and it has left low beam out. Swapped bulbs and they are good. Searched a bit and found that the internal ballast on these goes out and it basically unreplaceable so people do that upgrade mod with cutting wires and putting the integrated igniter/ballast in place. I bought a pair of these but cannot seem to get them to work
https://www.ebay.com/itm/New-OEM-Hel...p/114309576820
I followed the B&W official MB service doc about cutting the 3 wires off the old ballast and connecting the replacement unit, but I do not know how to map the colors. Off the car is Black, Green, Red. Off the new igniter/ballast is Red, Blue, Yellow. Also I tested voltage at the 3 wires on the chassis and don't see 12v, only something like 3-6V depending on the pairs. Maybe it wasn't the ballast after all?
Can I test the new igniter/ballast by just connecting it directly to 12V. If so, I wonder which 2 wires out of the R,B,Y is should use
Also, can anyone drop an image of the relevant wire diagram for the headlight end and where ever the other end of the hardness goes (SAM?)
https://www.ebay.com/itm/New-OEM-Hel...p/114309576820
I followed the B&W official MB service doc about cutting the 3 wires off the old ballast and connecting the replacement unit, but I do not know how to map the colors. Off the car is Black, Green, Red. Off the new igniter/ballast is Red, Blue, Yellow. Also I tested voltage at the 3 wires on the chassis and don't see 12v, only something like 3-6V depending on the pairs. Maybe it wasn't the ballast after all?
Can I test the new igniter/ballast by just connecting it directly to 12V. If so, I wonder which 2 wires out of the R,B,Y is should use
Also, can anyone drop an image of the relevant wire diagram for the headlight end and where ever the other end of the hardness goes (SAM?)
Last edited by tnken; Feb 6, 2021 at 12:45 PM.
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2003 C230K Coupe Orion Blue
That igniter you want is not the one in your photo, but a very similar variant which would have the correct pins. See here and here. Correct PN in the 2nd post, post #5. I would not recommend getting the incorrect one, as there is no way to know if the wiring schematics are the same without cutting open the unit.
Just took a look online (eBay). Not sure why there are versions with that PN where the metal ring (bulb side) is missing. Maybe it's a cost saving measure for the newer versions. I'd imagine the ring makes the part more durable, as it rubs against the headlight when installed and twisted. Personally I'd go for the older variant with the ring, but it's up to you.
Looks like people are selling the pigtail connectors separately, though the wire colours are incorrect.
The ballast is a completely separate electronics module, attached to the bottom of the headlights. These are not known to go bad.
Just took a look online (eBay). Not sure why there are versions with that PN where the metal ring (bulb side) is missing. Maybe it's a cost saving measure for the newer versions. I'd imagine the ring makes the part more durable, as it rubs against the headlight when installed and twisted. Personally I'd go for the older variant with the ring, but it's up to you.
Looks like people are selling the pigtail connectors separately, though the wire colours are incorrect.
The ballast is a completely separate electronics module, attached to the bottom of the headlights. These are not known to go bad.
Last edited by slammer111; Feb 8, 2021 at 08:41 AM.
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2005 C320 4matic
Thanks for the reply. I may be confused. I was trying to accomplish the upgrade described in this MB official service doc
https://mbworld.org/forums/attachmen...acement-1-.pdf
From what I understand, this replaces the separate igniter and ballast devices with a single unit that does both the igniter and ballast function with a module that mounts directly to the light. Correct?
I thought the device I bought was a suitable part and liked that it included a suitable cable. I guess from your comments, maybe I should instead get the orange/grey module you referenced, but I do not understand your comment "ballast is a completely separate electronics module." I thought these replacement modules had both functions
https://mbworld.org/forums/attachmen...acement-1-.pdf
From what I understand, this replaces the separate igniter and ballast devices with a single unit that does both the igniter and ballast function with a module that mounts directly to the light. Correct?
I thought the device I bought was a suitable part and liked that it included a suitable cable. I guess from your comments, maybe I should instead get the orange/grey module you referenced, but I do not understand your comment "ballast is a completely separate electronics module." I thought these replacement modules had both functions
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2003 C230K Coupe Orion Blue
The document you posted shows the igniter replacement. The old style igniter (the document calls it the ignition module) consists of a square module installed inside the headlight that powers the connector with the 2 rubber lines that are to be cut and discarded along with the bulb connector. The updated version can be seen inside your document, but attached to the cap instead.
The ballast is a separate electronics module that is attached to the exterior of the headlight at the bottom. This will be reused. If you reach underneath the headlight with the hood open you can feel a rectangular box. In fact, in p.5 of the document the ballast is visible at the very bottom of the photos.
The ballast powers the 3 wires (red, green, black) that run inside the headlight to the igniter. These are the wires that you need to cut and splice.
The MB dealer version of the replacement igniter is more expensive and clunky than it needs to be. The tiny square module I mentioned earlier does the exact same job and doesn't require the new lid. Why MB went the external puck route is completely beyond me.
The ballast is a separate electronics module that is attached to the exterior of the headlight at the bottom. This will be reused. If you reach underneath the headlight with the hood open you can feel a rectangular box. In fact, in p.5 of the document the ballast is visible at the very bottom of the photos.
The ballast powers the 3 wires (red, green, black) that run inside the headlight to the igniter. These are the wires that you need to cut and splice.
The MB dealer version of the replacement igniter is more expensive and clunky than it needs to be. The tiny square module I mentioned earlier does the exact same job and doesn't require the new lid. Why MB went the external puck route is completely beyond me.
Last edited by slammer111; Feb 8, 2021 at 04:33 PM.
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2005 C320 4matic
Ahhh, OK, so the part that's inside the headlight and effectively irreplaceable is the ignitor only. I'm not HID expert but OK with tools & such. My first MB...always been a Volvo & BMW person
Still feel like I might have some kind of other problem because when I turn the lights on (right side works fine), on the left side, I don't get 12V on any combination of the 3 leads I cut. Get like 6V or less. Does that indicate something else is broken?
Still feel like I might have some kind of other problem because when I turn the lights on (right side works fine), on the left side, I don't get 12V on any combination of the 3 leads I cut. Get like 6V or less. Does that indicate something else is broken?
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2003 C230K Coupe Orion Blue
I have no idea what the inner workings are for the individual circuits. However the wires inside the headlight have already passed through the ballast and probably don't provide the steady 12VDC you are expecting. That's why there isn't much point troubleshooting. It's much easier to simply replace the modules, starting with the igniters. There are only 2 things that can fail and prevent the HID bulbs from lighting up.
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2005 C320 4matic
Got it. Thanks for the help. Much appreciated. I'll proceed with swapping that under-headlight ballast to confirm it's OK (if that turns out to be easy'ish to do) and then if it's OK, replace my igniter with the orange/grey model instead of this metal shielded one
