Need a Tach Signal for 2012 Stelvio

[canuck1969]

In the middle of my Rostra Cruise install on my Stelvio and need a location for a Tach signal.  The phase sensor is available, but there are 3 wires that go to the ECU.  2 are labeled the same thing as Engine revolution signal at the ECU that was not very helpful unless either one is good. The third was labeled as an Anti jamming wire.

Is it easier to just tap into the coil.  And if so, which wire.  Assuming it is the one going back to the ECU which is the orange/green for the left coil according to the schematic.

I tried to figure out which wire at the back of the dash but the descriptions in the manual are a little vague.  Could not find anything remotely indicating RPM.

Any help would be greatly appreciated.

[beetle]

Yep, orange/green on the coil.

[beetle]

Or blue/green on the right. Whichever is easiest to get to.

[canuck1969]

Yep, orange/green on the coil.

Excellent. Going up the left side with all the wiring to the control switch so will pick it up on the way.

[ITSec]

Are you installing the old (vacuum-style) Rostra or the current (all-electric style) unit? If the older one, then the coil pickup works fine. If the newer design, then my sources tell me you don't want to do that. The new style wants an actual tach signal rather than a firing signal. There's a thread somewhere about installing the newer design in a Norge, I believe. If so, then the wire color info from that setup is likely very close to the setup on a Stelvio. I believe that write-up describes picking up the signal by splicing into a wire near the ECU connector.

[canuck1969]

Are you installing the old (vacuum-style) Rostra or the current (all-electric style) unit? If the older one, then the coil pickup works fine. If the newer design, then my sources tell me you don't want to do that. The new style wants an actual tach signal rather than a firing signal. There's a thread somewhere about installing the newer design in a Norge, I believe. If so, then the wire color info from that setup is likely very close to the setup on a Stelvio. I believe that write-up describes picking up the signal by splicing into a wire near the ECU connector.

Newer electric one.  Can't seem to find that thread but will keep looking.  I could bypass using he Tach and just use the clutch switch, but the switch does not make until the lever is all the way in.  Not the best scenario but better than nothing I guess. THere has to be a wire to the dash but damned if I can see it on the drawing or in the manual.  THere is no reference to a tach input to the dash. 

[Wayne Orwig]

My understanding is that there is a sort of 'can bus' between the ecu and dash carrying the tach and fuel information. Not practical to tie onto that.

[beetle]

Yes, it's CAN bus. Can't tie into that.

[canuck1969]

Yes, it's CAN bus. Can't tie into that.

Ok. Makes sense. Will try the coil and see if it passes diagnostics. 
If the coil does not work what about the phase sensor.  Any chance that would work. Three wires just not sure which one is the right one to tap.

[leafman60]

Ditto

Tap in at the coil.

[canuck1969]

Ditto

Tap in at the coil.

Will try it today.  I also tapped into the rear speed sensor for the speed signal.  Have read a couple of posts that since it is a two wire and does not have its own power supply it may not work.  Lets see what happens.  If not I will have to order the optional speed sensor.

[Xlratr]

Don't know if it's a suitable signal for what you need but there's always the injection signal. I tapped into the right side injector to measure rpm for AFR logging.


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[canuck1969]

Don't know if it's a suitable signal for what you need but there's always the injection signal. I tapped into the right side injector to measure rpm for AFR logging.


Sent from my iPhone using Tapatalk

Tach signal is good at the coil. The self diagnostics gave it a pass. Light flashes faster when RPMs increase.

Everything else passed diagnostics except the speed sensor. I was hoping it would work directly from the speed sensor but it does not.

Calculated the pulse to be 24,000 pulses/km by basically counting all the teeth on the ABS ring (48) and dividing by the diameter of the tire (1.995M).

I tapped right into the positive wire on the sensor plug itself, at least according to the drawing. It was the yellow/brown wire from the rear sensor. I will see if I can confirm it with my voltmeter. The drawing only labeled them by number and I went by the numbers on the actual plug.  Perhaps this is not correct.   Hoping the drawing is wrong.   

Anyone have any other ideas of where to get the signal from (ie. dash???). Failing that I will have to order the aux speed sensor. Was going for the factory look, but guessing that may not happen.

Beetle, I know you guys have worked with the pulse signal for the speed with Guzzidiag since there is a pulse generator on the site.  Any ideas which pin on the dash would have it, and will it be any different than what is from the sensor positive wire.

[beetle]

Wrong spot. Try using the grey/white wire from the ABS control unit to the ECU. That wire connects to the speed input of the ECU. Speed goes to dash via CAN.

[canuck1969]

Wrong spot. Try using the grey/white wire from the ABS control unit to the ECU. That wire connects to the speed input of the ECU. Speed goes to dash via CAN.

You the man Mark. Get a stead flash on the cc controller now when I spin the wheel. All diagnostics now check out. No time for a ride but will let you know how it turns out.

Assuming the pulse rate will be what I calculated from the abs ring and tire. Will start with that and see what happens.

[beetle]

Assuming the pulse rate will be what I calculated from the abs ring and tire. Will start with that and see what happens.

Probably won't be. The bikes with ABS have a map speedo correction value approx 7.5 times greater than non ABS. The signal that goes into the ABS unit may have no correlation to what comes out.

[canuck1969]

Probably won't be. The bikes with ABS have a map speedo correction value approx 7.5 times greater than non ABS. The signal that goes into the ABS unit may have no correlation to what comes out.

OK, lets see what happens.  I know the non ABS bikes are 6 pulses per revolution and the ABS are 48 (confirmed with the tooth count).  Hopefully the signal to the ECU is consistent.  Worse case it will be less and can start going down the dip switches in count until I get the one that feels right.  Trial and error, but start with what I know.

[canuck1969]

We have success. 

Started at the 48 pulses/revolution and it would not even engage.  Then halved it to 12 pulses and it would then engage but not until 90 KPH.  Halved it again to 6 which I know is what the non-abs Griso is set at from other posts.  Picked the closest on on the Pulse/KM settings on the unit (errorred on the high side) and worked like a charm. Kicks in around 40 km/hr.  Came out to 6000 pulses/mile or 3700 pulses/KM as the setting (about 7 pulses/revolution).  So it seems that the dash program is the same for ABS and Non-ABS, only the pulse rate into the ABS unit is different.  Makes sense.

Only tried it up to 100 KPH but will test further later.  Have to play with the gain settings.  Have it at low right now and seems to respond well to changes in terrain without being snatchy or surging.  May try ultra-low to see what happens.  Keeps the speed right at where I set it and engages quickly and smoothly.