Headlight repairs – 24V R2 bulbs

So normally, when your vehicle blows a headlight bulb, you just go to your local auto parts store and get a replacement.

You open the hood, twist the fitting on the back of the headlight, replace the bulb and twist it back in.  No big deal.

But it’s not that easy on a Unimog.  First of all, the Mog Mahal is a former German Army Truck.

That means it runs a 24V electrical system.  Second of all, it does not use a standard 9004 or H4 bulb.  Nope.

It uses a 24V R2 bulb.  These have to be special ordered.

So here ‘s the blown bulb from the MOG compared to the new one I was able to source.

24V R2 bulb

Here’s the model I was able to find.

I sourced it from Susquehanna Motorsports.


CP48894 – 24V – 75/70W – 2150 / 1325 Lumens


So how do you install the blub?

First you have to remove the frame around the headlight assembly.

Those two small screws on the sides of the frame come out and the frame comes off.

Then remove the six hex nuts from around the perimeter of the headlight.

Then carefully, tilt the lens assembly forward revealing the wires and connector.

You will see both the main halogen headlight bulb, and the smaller parking light.  Both of these bulbs are 24V.

Disconnect all wires.

The left and the right headlights had slightly different wiring for the parking bulbs.

On my truck, the brown wire is the ground or negative wire.


You can see the smaller parking bulb on the right. I ordered it from lightbulbs.com.  Osram – 4 watt 24 volt Miniature Bayonet Base #3930

To replace the main bulb, press and twist the grey metal cover counter clockwise.  It’s spring loaded and takes a fair amount of force to depress.

This reveals the R2 bulb behind it.

Pry out and swap out the bulb.  Reinstall the grey metal bracket, and reinstall the headlight assembly and the frame.

While I had the frames out, I sanded and repainted them.  The old paint was flaking off.

Then reconnect the wires, and reinstall.  Main light works!

And so does the smaller parking bulb.

Happy truck with both headlights working.

Baseline maintenance before we start to drive the Unimog home…

So the Unimog patiently waited in North Carolina for about five weeks, until I could get some time off from work.

In the meantime, I started buying parts and supplies and learning about basic maintenance.

Finally on August 11th, 2017 we flew to North Carolina.  Luckily we have a friend there who has a garage big enough and he let me work on the Unimog for two days, to get it ready for the drive West.

As this is a new vehicle to me, I needed to change all the fluids, do an oil change and a few other things before we drove 1,100 miles to Oklahoma, where I had another friend who would let me keep the truck at his place till I had more time to complete the drive to California.  (Remember, the Unimog only cruises at about 40 mph…)

So here’s the Unimog in my freind’s garage as I start to do some basic maintenance.

I had ordered and shipped all the lubricants and parts I would need, and had everything ready to go, including select pages from the factory service manual.

Unimogs are special in that they do not have traditional axles.  Each wheel has it’s own Portal Axle, and each wheel has it’s own set if gears and bearings.

I wanted to make sure that each wheel had new fluids.  Additionally I replaced both fuel filters, the air filter, oil filter and flushed the transmission and refilled with Red Line Synthetic lubricant.

Five days of “high speed” travel in the middle of a hot summer is not what Unimogs were designed for, so I wanted to do the best I could for it.

One nice thing about Unimogs is that the hood and grill come off easily to make working on them easier.

Fortunately, I had some help doing the work,  (Thanks Patrick) and  as you can see, you have to stand on the bumper to add the nearly five gallons of oil that this truck uses.

There were a few other things that needed to be sorted out before we could make the trip West.  Unimogs run a 24V electrical system, so I had to install a 24v to 12v inverter in the cab so we could plug in things like the GPS and a USB port.  But after two days, the basic maintenance was complete.


Thanks again Patrick for your invaluable help, and Glenn for letting me use your garage.