K75 24 point pin connection

[Atabeach]

Ok So I replaced odometer gears and upgraded to LED gauge lights. I Caaaarefully removed and replaced the 24 pin connector. All 12 volt lights, controls work ….I have the pin locator diagram, it seems like the lower left hand side 21, 22,23  seem to be not making enough contact…The connector has been removed and reinstalled a few times and may be getting “tired” My question: what pin points are NEEDED for tach and speedometer. What I’ve read;  21 Tach signal (cancel relay) 22, tach pulse, 23 tach encoder. Are ALL 3 needed to run tach? Also # 16 ( speed signal) ….my  options are 1) dielectric grease( tried didn’t work) 2)  carefully humor pin female tighter ( in process) 3 ) splice in new connector ( not a fan/ last resort…ps everything worked prior to disassembly..TIA

[rbm]

Minimum signal input for speedo input is 23 and 22 - yellow is active signal and brown is ground.  The output from the sensor on that wire is only about 2V peak-peak so any corrosion will impede the speedo function.  Try reseating the two pin connector under the right battery cover that leads to the speed sensor in the rear drive.  It might not necessarily be the 24-pin OEM connector.

pin 21 is an output from the OEM cluster to the flasher relay so has nothing with making the speedo work.  It's the signal that autocancels the flashers after some meters.

Tach signal comes on pin 16, black/blue.  That is an 80V signal so peculiar its not working for you.

[Laitch]

My question: what pin points are NEEDED for tach and speedometer. What I’ve read;  21 Tach signal (cancel relay) 22, tach pulse, 23 tach encoder. Are ALL 3 needed to run tach? Also # 16 ( speed signal)

The pinout guide you're using is inaccurate. rbm's explanation is supported by the guide at this link.

[Atabeach]

Thanks Laitch, so the odometer was turning but the speedo wasn't ...Could it be the 3 long pin connector inside speedo? I removed this to repair gears. In short, if the odometer is working then 22 & 23 are making contact at that 24 pin connector?

[frankenduck]

Thanks Laitch, so the odometer was turning but the speedo wasn't ...Could it be the 3 long pin connector inside speedo? I removed this to repair gears. In short, if the odometer is working then 22 & 23 are making contact at that 24 pin connector?

The 3 pin connector should not be an issue for a 94.

Follow the wiring from the speedo sensor in the final drive to its connector. If that rubs against the wheel then it can wear down the wiring insulation and cause issues.

It's also possible that your speedo sensor has failed.

[Atabeach]

Thanks for the reply, Im really thinking it is the 24 pin connector because everything was working fine that morning. I will, however check that sensor... To clear some questions: What drives the odometer motor? If the odometer motor spins, that would lead me to believe the speedometer should also...am I missing something?

[Laitch]

Thanks for the reply, Im really thinking it is the 24 pin connector because everything was working fine that morning. I will, however check that sensor... To clear some questions: What drives the odometer motor? If the odometer motor spins, that would lead me to believe the speedometer should also...am I missing something?

Keep an open mind; don't get theory-locked or flummoxed in a chicken-or-egg loop. You may be right; I may be crazy; Oh, but it just may be a lunatic you're looking for. The rear drive sensor sends impulses to drive a motor linked to the speedometer needle and to the odometer and tripmeter. It's a sub-magical assembly. Here's a diagram and there are more at this website (scroll down when linked). Also, relate what you see in the diagram to the photo illustration at frankenduck's site.



Inspect its wiring as frankenduck has suggested. Also carefully remove the sensor and clean it. Change the rear drive oil too, after its been warmed up.

[rbm]

I published the schematic for the OEM speedometer/odometer circuitry in this post:  https://www.motobrick.com/index.php?topic=10566.0

Both the speedometer stepper motor and the odometer stepper motor are driven by a common IC - a UAF0115 speedometer and milage indicator integrated circuit.  The pulses from the rear speed sensor get processed by the sensor amplifier board which sends amplified and shaped pulses to the UAF0115. So you're right - the odometer will only turn if the rear sensor is functional.  Your speedo indicator problem may be mechanical.

[Atabeach]

DONE! The bane of my Brick ownership...that 24 pin connector. I used Kopper Shield on contacts.. I tried Dielectric grease...this is essentially copper paste...Viola!  I took the speedo apart one last time to be sure the 3 pin connector had continuity and nothing was hanging up dials...The female contacts can get pushed back a little with time. Thanks guys!

[Laitch]