Author Topic: Chasing instrument unit problems  (Read 2917 times)

Offline wanderlust kid

  • Curious
  • Posts: 5
Chasing instrument unit problems
« on: May 20, 2013, 12:32:51 PM »
So I posted earlier this week about my instrument unit on my 91 K75S acting up. The Tach, gear indicator, and neutral light have all stopped working. Also now the bike will only start with the clutch engaged.

The speedometer and odometer and turn signal indicators are still working fine.

I have been trying to follow the lines in search of any corrosion. I believe the picture below is the connector in question but it won't come undone and doesn't look too bad from the outside. Is there another connectors I should be checking?

I also took the instrument unit apart but i'm quite lost as how to proceed any help would be appreciated.


Offline JamesInCA

  • ^ Proficient Motobricker
  • Posts: 133
Re: Chasing instrument unit problems
« Reply #1 on: May 20, 2013, 03:03:41 PM »
If I'm looking at it correctly, the first picture is the connector for your right-hand switchgear. The problems you describe don't involve that area, so I'd just leave well enough alone with that particular connector.

The fact that it's only starting with the clutch in is a clue to the problem(s), but not a definitive one. The starter button gets power from either the instrument cluster when it senses neutral, or the clutch switch.

So, if the start button is not getting power in neutral, that means either the cluster is having trouble receiving the neutral signal from the gear position sensor on the back of the transmission, or it's getting the signal but the outbound wiring from the cluster to the start button is bad. Both are quite possible, but it's the cluster connector that seems more often at fault. Since you have the cluster off, you've already disconnected those two -- the two rows of pins on the back. So you want to clean those pins really well, and also do the best you can with the sockets that receive them on the wiring harness. There's not really much you can stick in the sockets to clean them with, but you can spray contact cleaner right in them, and then give them plenty of time to dry before re-connecting them.

(Also, if you mean it'll only start with the clutch in when you have the cluster removed, that's to be expected as there's no neutral signal to the start button when the cluster is removed.)

Offline Chaos

  • Administrator
  • ^ Quintessential Motobricker
  • Posts: 3157
  • Mars needs women!
Re: Chasing instrument unit problems
« Reply #2 on: May 20, 2013, 07:32:48 PM »
http://www.ibmwr.org/ktech.shtml  scroll down to instrument cluster, lots of articles on fixing them
  • sw ohio
1987 K75S    VIN 0231
Original owner, Original litter
200,000 miles (plus or minus) and 5 paint jobs
sold 6/23
2023 Ural 2WD sidecar (BMW's bastard step child)

Tags: