I've wired extra lights into my cluster. I used the obvious wire connections soldered to the little boards that the old bulb holders twist into. The cluster lights come on when the headlights are turned on, and that's great.

But I now have one issue.

When I turn on my right blinker (or hazards), the cluster lights flash off and on while the blinder flashes on and off. The left blinker doesn't make it do that.

Does anyone know the proper way to wire extra lights? It bugs me a little. I might have to get the upgrade bulbs if I can't get this straightened out.

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1982 300CD Petrol/Black Leather

Just for my curiosity, what is the purpose of extra cluster lights? Make the gauges brighter and easier to read?

As far as the blinking goes, it means that you have wired the ground of your extra lights to the hot lead of the right turn signal indicator light. When you turn on the headlights, current flows from the battery through the headlight switch to the cluster, through your new lights, to the turn signal indicator light, through the turn signal lights themselves (which, not being turned on, are cold and relatively low resistance) and so to ground. So your new lights light up.

When you turn on the right turn signal, the place that you thought was ground now becomes +12 Volts. At this point, the right turn signal turns on and your new cluster lights, "trapped" between two +12 Volt points, get no current and turn off.

To fix the problem, all you have to do is find a "real" ground point for your new lights.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

I like that answer, but why don't the lights blink when the LEFT blinker is applied? The wiring is identical on both sides.

The mini-board for the right side light/blinker is independant with no way of grounding through a screw to a cluster gauge. It has three wires attached to it: black, red, and grey. I assumed that connecting to the red and black should give me power and ground. Maybe the gray wire is the ground, then?

But again, why doesn't the left blinker affect the cluster lights the way the right blinker does?

Why extra lights? That's a good one.
Did a PO replace your cluster lights with the hyper white upgrades or something? The original lights put out maybe .01 candle power?

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1982 300CD Petrol/Black Leather

I'll agree that the cluster lights aren't terribly bright but mine is acceptable. Was there an upgrade between 1983 and 1985? Did a PO put in brighter bulbs? I don't know, I've not yet had the dash apart.

If your extra bulbs are grounded through the right TS, then they should blink only when the right TS is active. The wiring may be identical but it cannot be the same wiring or both left and right TS would blink together. The ground leads may be common but the hot leads must be separate. If you have some extra lights wired on both sides and only the right side lamps blink, then you must have found the correct ground on that side. My only suggestion would be to try different ground possibilities until you get one that works correctly.

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Well, I looked at them a little closer, and I can now see how the circuit goes underneath the paint. The RED is connected to one side, and the GRAY wire runs to the other side of the bulb housing hole.

It's the RED and GRAY wires that power the dash light bulbs.
It helps to actually LOOK sometimes. Oh well...
I hope this post helps somebody in the future.

EDIT: I just reinstalled and tried them out. They are working beautifully! Thanks for the help! You were definitely right about the wires being connected incorrectly.
Now I wonder if I can get a U.V. bulb that will fit into the original bulb housing...


BTW, I had the extra lights on the right side wired to the black and red on the right side, and I had the extra lights on the left side wired to the black and red on the left side. They both blinked when I activated the right blinker or the hazards, but they didn't blink when I activated the left blinker. I see how the connection may have fed backwards when activating the blinker to make both sides flash. I'm just wondering why the left blinker didn't cause the same flashing as the right side.

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1982 300CD Petrol/Black Leather