I'm stuck with a car that has neither brake lights nor blinkers. Only 6
fuses have power.
I need to get at a wiring diagram to see the wiring between the ignition
key, the main lighting switch and the fuse box. Is there one on line
somewhere? I had hundreds of hits in my searches but they always end up with
What about the possibility of a temporary connection - a short one between a
powered fuse and the fuse that controls the faulty lighting? That would
allow me to get to a manual, with the wiring diagram. Possible burn out of
components as a result?
Thanks Gene for your effort.
I finally was able to get at my manual and believe that it IS the ignition
I scanned the wiring diagram and spent 30 mins setting it up on a web site:
Page 1 is the part of diagram with the fusebox and the ignition- and
There are two wires from the ignition switch to the fuses - one (red green)
goes to fuses 4 and 6 (coupled) and the other (red black) goes to point 15
in the fuse box, feeding fuses 8 through 14. Fuses 8 through 14 have no
power which suggests that the ingnition switch is
not providing any "juice."
Hopefully thaat web site will be able to spare someone my recent woes.
More info. Just checked with local MBZ dealer about the ignition switch. It
has 3 parts:
1 Ignition tumbler part - $111
2 Electrical portion - $31
3 Lock mechanism - $207
Not exactly cheap.
I'm hoping all I need is the electrical portion.
I don't recall tumbler being so high priced... but is adviseble to be
changed if you still have original tumbler. Yes, you basically only need the
ignition switch (electrical portion). The locking mechanism includes the
Thanks Tiger and Martin. Much apprerciated :-)
The car has only 85K miles on it and, although I could expect an electrical
part to go, I think mechanical parts should be more durable. If the tumbler
part cost about $30, I would replace it but, at the price quoted, I'll wait.
Now the problem is to replace the electrical part. My three big fat MBZ
manuals are broken down into an engine part, a body and electrical part and
a body part. I can't find any mention of the ignition switch. I also noticed
that the wiring diagram doesn't include a battery!!! I have a Haynes manual
that supposedly covers the E300 series but it doesn't mention an ignition
I had an idea today to short out, on the ignition switch, the circuit that
has no feed from the battery. This would get the car going again until I had
the electrical part. However, I need to get the assembly out and it's firmly
fixed. It is stuck in its socket, which is a short stub of pipe that sticks
out of the steering column and has a clamp around it to tighten the assembly
in place. I have the bolt very loose on the clamp and the assembly will move
out of place only about 1/8" and then hits a hard stop. Besides that
problem, I'm not sure it can come out without removing the dash. Anyone had
experience of removing the assembly?
It is in the chassis manual along with steering. To get the wiring harness
off, you need to have the key in position 1. To pull the entire assembly
out, you need to press in one metal tab... it is faced toward the rear of
the car (front seat direction)... easy way is to insert a straight stiff
coat hanger wire through the dash and guide it with your finger and push it
in.... then twist the entire assembly 90 degree and you can pull it out
Hold that thought!
The electrical portion of the switch is only attached by three screws and
you may not have to take the entire steering lock assembly out to get to the
electrical part. It should be a matter of unplugging the wiring connector
(the cylindrical plastic part with all of the wires going into it) by
pulling it strait off (forward) of the electrical portion of the switch.
Then you locate the 3 screws that hold the electrics to the lock mechanism,
loosen them and the electrical portion will come off. Reverse and your back
together. There will be some on your head, under dash work but no pain, no
Thanks again Gene and Tiger.
Had a look today with an inspection lamp at the switch assembly. I had
loosened the U clamp and the assembly moved out of place, away from the
steering column, by about 1/4", which gives me peeping room on the steering
column side. There is a channel machined into the casting there and what
looks like a plastic cable connector pushed into it. I can't see any more
there, apart from solid casting. I was able to get my hand around most of
the unit and couldn't feel anything that could be a tab.There is no tab
visible between the black cylinder and the edge of the hole in the dash. I
was able to push in a strong hanger wire and even a slender screwdriver
there, while rotating the black cylinder - but nothing gives. I tried the
same thing with the key in place but that didn't do any better.
Underneath I can see only a single small screw - about 3mm. There is another
one keeping the double tube unit (vacuum?) attached but it would be very
difficult to remove. I also noticed a small hole in the casting and when I
put a wire in there I couldn't turn the key, which suggests it might be what
is used to push out broken keys?
Thanks again for your patience
Thanks again Tiger,
I bought the electrical part of the ignition switch and I now have access to
all my manuals. However, I cannot locate the section where the ignition
switch is described. I have the engine manual and the chassis manuals parts
1 and 2. There is no index in any of them and the contents page for each
manual is truly abysmal - doesn't even cover a small fraction of what's
there. Which section is the steering wheel / ignition switch in? Thanks
When I was buying the part, I was told that there are two types of assembly
and I would have to know my chassis number to decide which was the right
one. Mine is wdb1231231a124698 but I think only the 123.123 numbers were
used. Maybe there is a tab on yours and not on mine. They gave me a copy of
the assembly drawing but it shows no tab - just the small electrical
connection on the assembly unit between the black cylinder and the steering
Went back to the car again and I am confident there is no tab on my
asssembly. I recognized the electrical part of the switch under the
electrical connector but it's very hard to get at. The connector is wedged
against a plastic duct (about 3" diameter) and, even with that connector
out, it would be very difficult to get at the screws as Gene suggested.
There are 3 marks on the switch around the black cylinder where the key
rotates, one near where the key is when first inserted and another further
around just about where the ignition is turned on, I believe, and a third
one around further where the car starts. I tried the key at various
positions, then pushed a screwdriver into the area you suggested - probing
all around, while trying to rotate the black part of the assembly - tried
both directions - wouldn't budge. There is also a small hole on the metal
cylinder that the key fits into. It is near the outer edge - at the inner
diameter of the black plastic part. Know what it is for?
I had a wire of the right diameter and I pushed it in there while rotating
but it didn't seem to do anything.
Thanks again for all the patience.
First of all. you are getting all mized up on what I am saying. This
steering lock/ignition is a very simple device. It is located in your
chassis manual... look by steering components/ instrument cluster. It is
there... because I have seen them in two of my chassis manual of two
Like I said, it is much easier if you just take the whole ignition lock
assembly out of the car. To get this out...
1. Turn ignition key to position 1... this release the steering lock that
prevents the steering wheel from turning.
2. Loosen that clamp nearby the steering column.
3. The round tab is located nearby the clamp faced toward the rear end of
the car. You cannot visibly see it from underneath the dash. Use your finger
to locate that tab... Use high power flashlight to assist in searching for
it if you try to look for it via front of the dash. It is there.
4. Once you located that tab, push it in with a stiff wire and then rotate
the entire assembly so the tab does not engage again.... then slide out the
If you do not want to remove the entire assembly, then you will have to try
to work around the rear using miniature screwdriver to remove the screws of
that ignition switch. A real pain. Again, your key must be in position 1 so
you can remove the wiring harness.
Huge thanks again Tiger,
Finally, I have all my manuals and found the section on the steering column.
From now on, where the manuals go, I go ;-)
The manual claims that the way to go about replacing the electrical part is
to remove the instrument cluster first.
You seem to have a slightly older version where the wire is pushed in on the
outside of the black cylinder.
For mine it seems that the wire is pushed in the hole, that I mentioned in
my last post, between the key cylinder and the surrounding black plastic
cylinder (the manual calls it the cap) is what releases the unit, with the
key at position 1. Numbers are not marked on mine. I don't understand why it
is necessary to go through so many steps to replace the electrical part. It
shows the instrument cluster removed to give access to the electrical part,
which is connected to the rest of the assembly by just three screws, as Gene
mentioned. If the key is in place it should align correctly when pushed into
Will remove the lock as you suggest and then try to take the complete unit
out to replace the electrical part.
At long last, hopefully I'll get this job done today. I've never had a
problem as long drawn out as this one.
Will report soon
Just remember, make sure the position of the key line up with your ignition
switch you got... because that key tab inside the lock thing will break
easily and that would force you to spend $200 for the new unit. I recall
spending $135 for mine at the dealer.
Thanks for the tip Tiger. $135 ouch! Condolences. Will watch it carefiully.
I saw how fragile some of the bits are.
I had no problem getting the lock off - after I found the right size wire -
a big paper clip :-) . Then I pushed in the detent down at the steering
column. That allowed the assembly to move out some more, but it still needs
about 5/8" to come all the way out of the socket and the whole area there is
so crowded that I cannot move it any further. I tried to pry off the big
cable connector to make some more room but had no success. Seems like I need
a knife to start it. It now looks like I will have to remove the instrument
cluster first and that in itself is another pain. The cables are so tight I
can barely find enough space to get a wrench in behind the cluster unit.
Struggle on ;-)
Some success. I found out why I was having so much trouble with the
instrument cluster and the lock. It must have been a Monday morning
assembly. Both the oil pressure cable to the cluster and the vacuum tubes to
the lock were routed in a roundabout way that made them both tight. I have
rerouted so this shouldn't happen again.
I replaced the electrical part but am puzzled by a small difference from the
one I removed. Looking into the center of the new one, I see a slot of about
1/4" x 1/2" and in it is a round plastic rod with a slot across most of the
width. Thie top of this is the level of the bottom of the pins i.e nothing
sticks up. In the old one there is a mason's hammer (a head on each side)
like piece of plastic that projects up from the same size slot - 1/4" x 1/2"
that the other one has. This "hammer" projected up about 5/8" and fitted
into a slot on the cable connector. I tried to remove it to install it in
the new one but it is built into the unit.
Looks like light at the end of the tunne :-)
Have an enjoyable weekend,
More progress but a glitch.
I have everything connected to the lock assembly - vacuum tubes and two
electrical plugs - but the the unit won't move far enough down towards the
steering column. The detent near the steering column is out in its place but
the assembly seems to be about 1/8" out too far* - judging from the position
of the key cylinder unit in the hole the instrument panel. In that position,
I screwed the black cap back on, aligning the necessary bits, and then
removed the wire but the key would not move at all. When I was disassembling
the assembly, I turned the steering wheel a little to the left (it was one
of the instructions) and after reassembly, I turned it back but it didn't
* I pushed in the detent and then pushed the assembly towards the steering
wheel but it wouldn't budge.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.