Switches on the 84 4k center diff

Mark J. Besso mbspeed at maxboostracing.com
Sat Jan 17 14:07:00 PST 2009

That looks like the switch that senses when the car is in top gear to 
prevent the upshift light from coming on.


On Sat, 17 Jan 2009 14:38:05 -0500
  "Bares, Vittorio" <Vittorio.Bares at nuance.com> wrote:
  I suspect all the attached pic's will get stripped for the forum list...
  However, I removed the two switches and they are identical...they both
  have a prong that is spring actuated.
  I would tend towards the 5th gear hypothesis...
  If you're interested in the pics - send me and email and I'll shoot them
  to ya.
  Vittorio -
  -----Original Message-----
From: Mark J. Besso [mailto:mbspeed at maxboostracing.com]
  Sent: Saturday, January 17, 2009 2:16 PM
  To: Louis-Alain Richard; Bares, Vittorio; Audifans
  Subject: Re: Switches on the 84 4k center diff
  IIRC, the UrQ didn't offer the option of locking the center or rear
  differentials individually.  You pulled one switch and they both locked.
  The 4KQ & 5KQ allowed that to be done in two steps.  You pulled the switch
  half way out to lock the center, and the rest of the way out to lock the 
rear too.
  Vittorio is trying to achieve a setup that allows individual locking of 
  center & rear diffs.
  On Sat, 17 Jan 2009 13:12:44 -0500
   "Louis-Alain Richard" <larichard at plguide.com> wrote:
   I shoulda've know that you are able to distinguish a plug from a 
   I took a look to the 1983 urQ spare tranny I have here, and there is no
   other switch on any part of the body. And there shouldn't be any... so it 
   probably an aftermarket switch. Do you have access to it ? Maybe this is 
   temperature switch that someone installed to monitor diff temp ? Or maybe 
   pickup point for a rally computer ? This would be a nice spot, less 
   by individual wheel speed.
   Do you have a picture ? Maybe we can figure what's behind ?
   -----Message d'origine-----
   Yes indeed that is the plug that is used to carry the diff lock cable.
   #26 is also identified as the diff lock switch (oriented East to West on
   the center diff).
   However there is one more switch that is installed in a North to South
   orientation - towards the top of the center diff, that is not identified
   in any of the 4k - in fact they all look the same from the ETKA point of
   The back-up light switch is further forward - just above the cv shaft
   Anyone know what this unidentified switch does?
   Vittorio -
   -----Original Message-----
   Hi Vittorio,
   This part, item 25 from page 32-00, is not a switch. It is the attachment
   point for the diff lock cable end, a sort of special bolt with a groove
   for a circlip. Just zoom on the part, and you'll see.
   -----Message d'origine-----
   There are 2 switches on the 84 4k tranny center diff - my ETKA tells me
   one is NLA and the other is the diff lock indicator (shown as the upper
   Anyone know what the lower switch is?
   Vittorio -

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