How To Replace The Indicator Bulb of a Mercedes Benz MB100D Van

One of the downsides of living in a big city is petty crime. The other day when I got up to go to work I found that someone had stolen one of the indicators of my Mercedes Benz MB100D van! So today I'm going to explain step-by-step how we replace the entire indicator assembly. At the end of the post I'll also explain how to change just a blown bulb (more common).

If you are replacing a damaged indicator assembly the first step will be to remove it. Since someone has already done this for us I will just say that removal is simply a matter of reversing these steps!

Once you've removed the old/broken assembly, the next thing to do is remove the indicator bulb holder from the new assembly and connect it to the wiring loom. Copy the connections from the old indicator bulb holder (Since I didn't have anything to copy I connected the brown wires to the tip of the bulb - in fact I don't think it matters which way round you connect them).

This is easiest done before the indicator housing is replaced. The wires are easier to get at from the front of the van through the gap left by the missing indicator assembly.

Simply push the 2 spade connectors into place then gently hang the bulb holder and bulb into the wheel arch as shown. Now is a good time to check that everything is working correctly. Turn the ignition on and check that the direction indicators and the hazard lights now function correctly . There's no need to start the engine, if everything is OK the indicators should now work.

If they don't check the following:

1. That the spade connectors are connected and that they aren't short circuited.
2. That the fuse hasn't blown ( The fuses are on a board under the dash by the steering column. The indicator fuse is the fourth one down on the right hand side. If it has blown change it for a 7.5A replacement - check for short circuited connectors first)
3. That the relay isn't working. The Mercedes Benz MB100D has 2 relays related to the indicators, one for the hazard lights and one for direction indicators. They are on the fuse board under the dash and are the 2 larger relays.



Connect the bulb holder and check the indicators work correctly before replacing the assembly

Carefully let the indicator bulb hang down inside the wheel arch

Once you've checked that everything works and the bulb is hanging inside the wheel arch you can now fit the indicator assembly in place.

This simply clicks into place and is held there by the 2 integral clamps. First you locate the tabs at the side of the headlight then push the assembly home until it if firmly seated. You will hear the 2 plastic clamps at the back of the headlight click into place but keep pushing until the 2 outer grooves locate firmly on the van bodywork. You need to push fairly hard to get it to locate totally flush with the wings. Don't be afraid, I ended up giving brisk taps on the indicator lens with the heel of my hand to get it to sit fully flush.

The 6 location points

Once the Indicator assembly is fitted you can twist the bulb holder into place. This is done from below,reaching up from the wheel arch. The good thing about older vehicles is that there's plenty of space to do this!



Twist the bulb holder into place from below

Here's a few more detailed photos that might be useful.



Spade connectors of replacement bulb holder



Replacement indicator housing showing 5 of the 6 locating points

IMPORTANT
If you're simply replacing a blown bulb then you don't need to remove the whole assembly. Simply reach up from below the wheel arch and twist the bulb holder out (quarter turn anti clockwise). Replace the bulb then twist the holder back in place.

If after doing this the indicators don't work check the fuses (panel under the dash next to the steering column) and relays as described above.

As always - If you have any questions or comments please leave a comment below and I'll try to help out if I can.



Fixing up a cheap electric guitar so it plays like a more expensive one !

A friend of mine called me up last week to ask if I’d take a look at a guitar for him. Apparently his girlfriend had bought him a cheap Stratocaster copy online for his birthday but the guitar was totally unplayable. He was pretty stressed because he didn’t want to tell his girlfriend that she’d wasted her money!!

To be honest I was surprised how bad the guitar was! I understand that it was very cheap, but it was truly unplayable. I was especially surprised since it is a Yamaha guitar, albeit their most budget model. I’ve played several Yamaha guitars over the years and they’ve always been good instruments. In fact I have an old Yamaha Pacifica as a reserve electric guitar. Actually this guitar was so bad that I suspect that is probably a factory second or a knock –off copy or such being sold online by an unscrupulous dealer.

Whatever, in the end it only took a couple of hours work to get it playing pretty well (in fact once I’d finished with it I had it pretty much set up to the same specs that Fender set their guitars up to when they leave their factory !) Anyway, here’s how we fixed her up.

First of all I tuned the guitar to pitch and tried to play her. Terrible, even with the strings set pretty high from the fret-board it buzzed and rattled and at some frets totally fretted out.

My first step was to try and straighten the neck using the truss-rod. I was pleasantly surprised to find that the truss-rod worked and that I could get the neck almost totaly straight under string tension. In fact you never really want a totally straight neck on a guitar, a slight relief is necessary to allow for the curve of the vibrating string. Most importantly, the neck wasn't twisted ( a twisted neck can often be fixed , but its a lot more work).

So now with the neck acceptably straight I proceeded to check the frets to see if they were level. A quick check with my Stew Mac fret gauge showed that the frets had never been levelled or dressed in the factory. (Note: This is hardly a surprise with such a cheap guitar; even fairly expensive guitars need to be taken to a Luthier to have the frets dressed if they are to play at their best.) It also showed up the reason why the guitar was unplayable: Frets 2 and 19 where ridiculously high, to the extent that I thought that maybe they weren’t correctly seated, they where. Actually I suspect that the other frets had been inserted with too much pressure and for some reason these 2 frets had stayed high.

This photo shows how we check the frets for level, we test 3 frets at a time - if the middle fret is high then the guage rocks, if not it stays firm. Please note that this photo is taken on a different guitar and with the strings removed.

Step 1 – Level the frets.



Since this guitar ( as is the case with most Stratocaster copies) has a screw on neck. The first thing to do is remove the neck (actually the first step is to remove the strings then the neck). Next we remove the plastic nut and re-straighten the neck sighting down the fingerboard with a straight edge. (Note: we want the neck as straight as possible at this stage). Guitar fret-boards are normally made of a hardwood like maple, rosewood or ebony. In this case I noticed that the fret-board was made of a softer wood dyed black to look like ebony. This is probably why the frets were so bad.

Once the neck is removed and straight I tape off the fingerboard with masking tape to protect it while I level the frets. Many luthiers use a metal file mounted on a wooden handle like the one in the photo below to do this. I find I get better results more quickly using a metal spirit level with sandpaper stuck to it. This has the advantage that it is almost as long as the guitar neck so it helps prevent you from sanding more in one place.

First I concentrate on numbers 2 and 19 (always working in the direction of the strings line and checking for level and profile) to quickly bring the two high frets down. Once the 2 rogue frets are about the right height I ink up all the frets with a marker pen and then work very carefully to maintain the correct profile. If you work carefully you should just need to keep sanding until the ink has just started to be removed from the lowest fret . At this point all the frets should be at the same height. We check with the straight edge, until we are totally happy that the frets are levelled.



Step 2 – Re profile the frets



Guitar frets are a half moon section. But the levelling process will have caused them to be flattened off. Flat frets rattle and play out of tune. So the next step is to round the frets off using a special small file with a rounded face (see photo). Whilst doing this you should keep checking that you maintain the correct fret-board radius using the plastic radius gauges (mine came off e-bay). Once the frets have been rounded off you should polish them up using different grades of emery cloth, wire wool and finally metal polish.





Step 3 – Neck back on



Once we’re happy with the fret job, we remove the masking tape, replace the nut and bolt the neck back on to the guitar. At this step I check the neck angle using the straight edge and find that it’s not as it should be. This is easy to fix on this type of guitar using card shims in the neck joint.



Step 4 – Final setup



Next we string the guitar up with a new set of strings ( I prefer ernie ball 10 guage) and bring them up to pitch. She’s already starting to play better, no buzzing or choking strings. But the action is still high, so we adjust the neck relief with the truss rod and the individual saddle heights using Allen keys.



Step 5 – Play and enjoy



Considering how cheap this guitar was, I was very pleased with how it played once we’d fixed it up. If the guitar were mine I’d probably have made a new nut for it too which would have seen yet more improvement.