k100LT '91 cafe racer. Issue with gear switch cables that do not ground.

[mlimiti]

Hi all,
I am new in the forum.
I have finished my k100LT cafe racer but I am struggling to make the gear indicator/neutral circuit work.
I have used the circuit that I found in the original instrument and placed it under the seat.
I have tested the circuit stand alone tonight using a 9V normal battery and the circuit works and is not the problem.
I have instead checked if the gear switch cables (Y/BLACK, Y/BLUE, Y/W) are grounded and none of them is in any position.
The gear switch should not be the problem because the gear indicator was working before I removed the original instrument.
I believe that the problem is at some point in the earth wiring and might have been casued by me pulling some ground cable for crimping.
Does anyone have any idea of how I could check and inspect the earth wiring that could cause the problem?
I also attach a photo and wiring of connections I made on the circuit:
-leerl with Black/green to starter switch (with diode) and neutral indicator
-15 with Green/white from power 12V
-31 ground
-A/B/C yellow/coloured cables from gear indicator

Thanks for your help

[rbm]

It is unclear from your photos what ground wire is represented being plugged into the board.  Is it the brown wire from the TGPI switch?  Is is a frame ground wire?

If it is the first case, you are not providing the circuit card with a path ot ground.  Install a frame ground wire in addition to the brwn wire from the TGPI.

If it is the second case, you are not providing a ground reference for the gear circuit.  Tie the Brown wire from the TGPI to a frame ground.

Try these solutions and get back to us.

[mlimiti]

Second case: I have indeed connected the brown wire from the board directly to the frame. How can I get to the tgpi brown ground wire? From Haynes manuals it is connected to the ground point 31/III (see pic attached).

[rbm]

The TGPI brown wire is connected to the frame under the tank.  Have you checked to make sure you have continuity to that point through the harness.

1. Unplug the TGPI connector in the battery tray area.
2.  Use a digital ohm meter on a low ohm range setting (better yet with a continuity function) to measure for continuity at the HARNESS side of the connector to frame ground.  Stick one probe into the connector and use the ground point on the battery's negative lead for the other probe.

If you have continuity to frame ground, the trouble may be poor connectivity in the connector itself.  Or it may be a bad switch that requires more trouble shooting.

If you don't have connectivity, then trace the wiring to find out where the ground wire goes in the harness and why it's not connected.

Exactly what symptoms are you seeing?  Is the digital readout always blank?  Is the gear display indicating the correctly selected gear?  What is indicated on the gear display when the transmission is in neutral?

[mlimiti]

Hi robert,
displaly shows nothing but when I ground manually the yellow/coloured cables the dispaly goes off.
I checked the gear switch connector placed along the frame at the right side of the battery for continuity and multimeter never goes off in any of the gear positions.
I believe that the gear switch must be faulty or hopefully it is just a slack connection.
This is however surprising because it used to work before I replaced the original instrument with a motogadget one.