rheostat bypass

[Valvechatter]

hello all,
to get my dash lights working it was suggested that I use a rheostat bypass as described in the technical manual. Today I opened the 12 pin box and discovered that my wiring in the box is somewhat different than what is pictured in the technical manual. The tech manual has a photo of the box that has a pin with one grey with blue tracer wire on a post and a grey and violet wire on a separate post (next door to one another). See image below: tech manual reo1a

My 12 pin box has three grey and blue wires soldered together on one post and next to it is a post with the grey and violet wire. See photo Rose 280SL Reo wiring

I don't know where all three of the grey and blue wires go so I am hesitant to solder the jumper wire to connect the two posts to effectively eliminate the rheostat.

Am I safe going ahead? What do the other two grey and blue wires go to?

I looked at the wiring diagram for the USA  in the technical manual but I could not make much of it since it did not have wire color codes on the wiring lines.


All help would be appreciated!!

Lin


 

[Jonny B]

Take a look at Pagoda Notes, Volume 4 no 3. There is a discussion about the rheostat bypass and set up.

[Valvechatter]

Jonny B.
Thank you. I have read this piece. Well done and helpful. However, it does not address my question - it actually generated my question. The article talks about using a jumper wire to connect two wires - the grey/blue and grey/violet. My 12 pin connection box doesn't have just one grey/blue wire, it has three soldered to a single post. I assume (always dangerous) that since the wiring diagram for the 280 shows three grey/wires going to the rheostat - one then to the speedo and one to the tach that it will be OK to solder the jumper wire from the three grey/blue wires to the one grey/violet wire. But, it would be great to get some confirmation that this is correct.
Lin

[66andBlue]

Lin,
the photo from the technical manual in your first post shows the cable with the male connector from the center cluster instrument with the rheostat.  Your second photo shows the cable from the main harness with a female connector.
Al Lieffring's bypass described in PagodaNotes and in the Technical Manual concerns only the male connector which needs to be modified by adding a jumper wire. You do NOT change the wiring on the female connector as you had in mind. It also should be easier connecting two single wires than one triple-wire and a single wire.
You wrote "...  it did not have wire color codes on the wiring lines ..". Have you downloaded the colored wiring diagram from the technical manual?  See: http://www.sl113.org/wiki/Restricted/ColorWiringDiagrams.
These diagrams show the wire colors and the wire thickness, but the color symbols are in German and you need to look at the translation table that is part of a different file (http://www.sl113.org/wiki/Electrical/WiringDiagram).

Lastly are you really sure that the rheostat is burned? Most of the times some fine granular dirt is wedged between the resistance wire and the contact wiper that prevents contact. A good flush with an electronic contact cleaner goes along way to restore its function.
Measure the resistance across that wire first before starting to bypass it.

[Valvechatter]

Hi Alfred,
Thanks for your reply. I was able to get the wiring diagram - with the wire codes - so I am now able to track the wires. Thank you. However, I do not understand your male/female comment at all. It looks to me that I am using the same positioning as in the tech manual. I am sorry, but I just don't see what you are describing. Some additional guidance?

Lin

[Valvechatter]

Alfred,
Sometimes you just need a good night's sleep! Took a look this morning and now see exactly what you mean. Yes, I will work with the male end of the connector box! Sometimes these things can make you feel so foolish! Thanks again for setting my straight!
Lin

[66andBlue]

Lin,
same problem here, sometimes it is not enough sleep and the other time its the wrong glasses. 

[Valvechatter]

Thanks to Al, Alfred, and Jonny B for the help on the rheostat bypass. Mission complete and I now have dash lights - at least most of them. I may have a few dead bulbs. I will wait till tonight and evaluate in darkness. Thanks again for the assistance. One more item checked off my list.

Lin