Author Topic: Rebuilding engine wiring harness - looking for help  (Read 1421 times)


  • Vintage
  • ***
  • Posts: 537
  • W116 Enthusiast
  • Location: Salt Lake City, Utah
Rebuilding engine wiring harness - looking for help
« on: 17 November 2019, 11:48 AM »
This should be a very easy problem.  One branch of the harness towards the back of the engine has a brown plug.  See picture.  This goes to a thermal time relay associated with the cold start injector.  I made a diagram when taking the plug apart but failed to note if it was looking from top=>down or bottom=>up.  Yah, I know, should have taken a picture.  Damn. 

Anyway, now I don't know if I should assemble the plug as pictured or with connectors reversed.  Would anybody be willing to have a look at this plug in their car and tell me?  The wires going into this plug are easy to see, there's no boot on it.  Getting it backwards would be quite bad I think.  I'd go look at the car and diagnose myself but it's across town and I'd like to check this subproject off my list.  Help would be greatly appreciated, as always. 

Incidentally, I think this job is very worthwhile.  Lots of the wire insulation was very hard, there were cracks, and much of the sleeving was in terrible shape.  I greatly doubt I'm the only one.  Seems like a bad connection or short would just be a matter of time.  It's not a hard job, just sort of tedious (I soldered in splices, no crimps).   Thanks and cheers,
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0


  • W116 Addict
  • ****
  • Posts: 1,502
  • MB Enthusiast
  • Location: Fort Collins, Colorado
Re: Rebuilding engine wiring harness - looking for help
« Reply #1 on: 18 November 2019, 01:28 PM »
The. Brown wire goes on the left side when looking at  the  top.

Prob doesn't make any difference as temp sensors work either way.
'68 250S, '77 6.9 euro, '91 300SE, '98 SL500 '14 CLS550