GRiSO speedo failure but sensor working

Evening all. My 2010 GRiSO 8V is reporting my speed as zero and I think the sensor isn't the problem. Anyone know what I could check next?

A while back the speed shown in the speedo became erratic, jumping between values that had no relation to the actual speed. There was an ECU 56 error. So I replaced the sensor, assuming that the Scottish weather had got in there.

With the new sensor the speed was initially erratic again then just reported zero speed. Once, after riding for ~30 minutes, the dashboard showed the correct speed for the remaining hour of the ride, in rain. Then afterwards permanently showed zero speed. Again there was an ECU 56 error.

So I replaced the battery, which was ageing but didn't appear to have a problem. I also tested the harness for the speed sensor, and it showed 12.55V across pins 1-3 with the ignition on, which I think shows that harness is powered.

I also tested the sensor itself, across pins 2 (sensor) and 3 (ground) whilst I rotated the wheel. Voltage went from 11.3V to 0.37V as the sensor activated. For good measure I also inspected the ECU connectors. They looked to be dry and clean but I sprayed them with contact cleaner anyway.

I do have another enduring minor problem with startus interruptus. Fitting the MPH kit has improved the situation but I still need a high-rated fuse, and occasionally get the click but no starter. Could be related. Or not!

Any ideas?

If you are sure the speedo sensor is OK, have you tried "resetting" the dash?

Disconnect the battery. Connect the +ve & -ve leads together, and leave the key switch on for at least an hour (overnight better).


Can't hurt.

I'd have to say it still sounds like the signal isn't getting through so maybe not the pick up itself but maybe the plug on the other end or one of the pins in the loom.

Thanks both!
Beetle - I'll do that first.
Pete - my next check will be to poke the multimeter into the back of the loom-side connector for the speed sensor.

On the “Startus” I use a 20amp fuse with the MPH kit. It came with a 15 in it and it would blow periodically.

The dash reset didn't seem to make a difference.

Having tested the sensor from the loom side of the connector, I'm not getting the change in voltage as the sensor activates, just a constant ~11V. I then rechecked from the sensor side of the connector and unfortunately had the same result.

So the sensor that was working three days ago now isn't. I'm assuming that I've either got a temperamental sensor, or there's something else that could be interfering.

Unless anyone has a better idea, I'll order another new sensor and try that.

Where are getting the ground for your meter? I'm wondering if it's a grounding issue.

Hey Beetle, here are the Voltage tests I did, from a couple of weeks ago when the sensor appeared to be activating, and today, when it isn't.

Test	04/03/23	25/03/23
Battery (ignition off)	13.3	13.4
Battery (ignition on)	12.4	12.5
Harness power to connector ground	12.6	12.5
Harness power to battery -'ive	N/A	12.5
Sensor power at connector	12.6	12.5
Sensor activation	11.3 - 0.4	11.0

For the sensor test, where did you ground the meter? On the battery? Sensor ground?

beetle wrote:

For the sensor test, where did you ground the meter? On the battery? Sensor ground?

On the sensor ground - poking the multimeter into the back of the sensor connector. Not the loom side, the sensor side.

I swear this bike is messing with me. I took it out for a ride today and after about a mile, in the rain, the speedometer started working again, and kept working for the whole 15 mile ride. I'm going to keep an eye on it over the next few rides.

So I'm summary, the speedo seems now to be reliably working again. I'm not sure what to make of it, or whether there's anything of benefit to others. But here's the sequence of events, that may, or may not, be relevant:
- Speedo became erratic and then stopped working, showing 0.
- Replaced the speedo sensor, and on a short test ride the speedo was erratic again, then failed entirely, again showing a 0.
- On a longer ride, in wet weather, the speedo started working again, showing the correct speed, and worked for the duration of the ride. On subsequent rides it didn't work, showing 0 again.
- Cleaned the speedo sensor connections. Cleaned the ECU connector. Replaced the battery. Speedo still didn't work.
- Checked the sensor, and loom, with a multimeter, and everything appeared fine, with the sensor activating as the wheel turned.
- Speedo still didn't work on a short test ride.
- Reset the dash (thanks beetle), and on a ~100m low speed test ride the speedo didn't work.
- Checked again with a multimeter, and no activation with the wheel turning.
- Went on a longer ride, in the wet, of ~15 miles and the speedo started working almost immediately, but at the same time the rear left indicator failed.
- Indicator bulb was fine, so tightened connections in the bulb holder, and the connection to the loom. Indicator started working consistently again.
- Speedo has worked consistently since, across several test rides of varying distance in the wet and dry.

Makes little sense to me, other than electrical gremlins, but hopefully useful to someone!

My guess is that there was a bit of corrosion in the white connector block for the speedo pick up.
removing and replacing enough times has disturbed the corrosion and remade connection.

I suggest that next time the panels are off - scrape the pins sides with a fine screwdriver and then vaseline the upper part of the connector (stop water getting in and allow any that gets in to get out).

Its working now - go ride