Speedo Problem

[motorman455]

I am experiencing a worsening problem with the Speedo on my 99 Busa. It is victim to the typical speedo bounce which has gotten worse over the past year. I've seen many people here have the exact same issue but most were related to the countershaft nut backing out. I checked that and all was ok and I just replaced the sensor with a new part. Now instead of the needle jumping it will sit at 20mph with the bike idling. If I turn on the brights it goes down to 10mph then applying the brakes makes it go to 0! I am thinking it is voltage/ground related but have not found an issue. Voltage is checking at at 14.1V and I checked the ground connection right near the battery. Is there a diagram which shows all the grounding points or is there just the engine cases and the connector near the battery?

I've seen many posts here on this exact same issue but besides the countershaft nut issue, I am not seeing what the root cause is. Many people take the bike to the dealer then don't follow-up with what the problem turned out to be. Any ideas? The speedo is pretty much useless at this point.

 

[300Busa]

I just fixed the speedo on my wife's jeep. The wire going into the speed sensor was broken inside of the insulation. It may be that some moisture got into the wire and caused some corrision....I am just guessing.

 

[proud dad]

have you tryed the wiggle test?wiggle the harness and watch the speedo while it's idling.or how the plug on the back of the cluster?as far as grounds in the manual,I'm only seeing the one at the battery.

 

[motorman455]

Yeah I've tried wiggling the connector at the cluster and at the sensor connector as well as the battery ground connector. That doesn't seem to influence the speedo but revving it up or turning on brights or brake lights does so it seems current related. Could this be related to the rectifier/regulator I wonder (ie less voltage = closer to 0mph at idle)? At least the problem has become so repeatable that it's easy to run these verifications. It used to only happen when I was slowing down and on the brakes then it started bouncing while cruising and now it's happening while idling in the garage!

The sensor connector contacts look clean as the bike never really gets wet besides washing.

It seems like there are many occurences of this problem. You would think Suzuki would have some sort of bulletin out. I don't want to put down $600 for a new cluster only to find out that it wasn't the problem. I already wasted the $70 on a sensor...

 

[proud dad]

go to this thread and down load this manual it has electrical diagrams in it.
https://www.hayabusa.org/forums/?act=ST;f=24;t=29016;st=0

 

[proud dad]

B/W wire [black with white tracer]with what you described in your first post,if there's a problem in this curcuit,hitting your brakes or turning on your brights would kill the speedo.Main ground for that curcuit which leads to the ECU.Something to check before you spend $$ on a cluster.

 

[proud dad]

Yeah I've tried wiggling the connector at the cluster and at the sensor connector as well as the battery ground connector.  That doesn't seem to influence the speedo but revving it up or turning on brights or brake lights does so it seems current related.  Could this be related to the rectifier/regulator I wonder (ie less voltage = closer to 0mph at idle)?  At least the problem has become so repeatable that it's easy to run these verifications.  It used to only happen when I was slowing down and on the brakes then it started bouncing while cruising and now it's happening while idling in the garage!

The sensor connector contacts look clean as the bike never really gets wet besides washing.

It seems like there are many occurences of this problem. You would think Suzuki would have some sort of bulletin out.  I don't want to put down $600 for a new cluster only to find out that it wasn't the problem.  I already wasted the $70 on a sensor...

the B/W wire is also the ECU ground for the rectifier

 

[motorman455]

yeah my next step was going to be to ground that Blk/wht wire directly to the battery from the cluster and see if the problem goes away. I was looking for the grounding diagram in the manual but didn't see anything. I guess thats probably because there is only one main ground wire to the frame which is from the battery to the engine case at the starter.

I attribute the speedo reacting to the brake application because the brake lights go on and the voltage drops just as when the brights are turned on but it may be a bad/loose ground.