Author Topic: Stepper motor ground issues  (Read 1625 times)

Offline muddyjwj

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Stepper motor ground issues
« on: October 22, 2021, 12:45:10 PM »
Hello!  I've spent the past few hours searching for a way to solve my ECU62 error (stepper motor ground) with no success.  I've recently had the ECU disconnected to check for corrosion on pins due to previous error that seems to have been related to a bad plug cap.  I replaced the plug wire boots with NGKs, but now I'm getting the stepper motor ground error.  Any help in locating the stepper ground wire connections or any advice on how to solve the issue would be greatly appreciated.  THANK YOU!

I have a 2010 Stelvio

Offline Kiwi_Roy

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Re: Stepper motor ground issues
« Reply #1 on: October 22, 2021, 12:57:24 PM »
I think you must be referring to the idle speed stepper motor item 40
https://www.thisoldtractor.com/guzzi007/schematics/2008_Stelvio.gif
Perhaps unplug the cable at the motor to see if the alarm goes away.
« Last Edit: October 22, 2021, 01:03:11 PM by Kiwi_Roy »
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Offline muddyjwj

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Re: Stepper motor ground issues
« Reply #2 on: October 22, 2021, 03:06:35 PM »
Thank you so much for the wiring schematic!  If my memory serves me correctly, access is behind the battery?  Or, must I take the tank off?

Offline guzzisteve

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Re: Stepper motor ground issues
« Reply #3 on: October 22, 2021, 03:10:10 PM »
If it is the stock metal body stepper best replace with newer plastic one. Check which one you have.
The service manual tells you which pin is ground, look it up & clean pins.

The stepper is in the center of throttle body rails.
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Re: Stepper motor ground issues
« Reply #3 on: October 22, 2021, 03:10:10 PM »

Offline muddyjwj

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Re: Stepper motor ground issues
« Reply #4 on: October 22, 2021, 08:28:01 PM »
Thanks GuzziSteve!  I checked the connector to the ECU and all of the pins look pristine.  The stepper is a metal one.  I can see the connector on the stepper motor, but it looks like a tank-off job to get to it.  I think I'm going to get a set of stubby hex wrenches and check the ECU ground first.  Before buttoning everything up I'll squirt some carburetor cleaner into the stepper.  If that doesn't solve it, I'll have to pull the tank to get to the stepper connection.
Is it a possibility that even though the code is for a ground fault the issue could lie elsewhere (dirty or clogged stepper motor)?

Offline Kiwi_Roy

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Re: Stepper motor ground issues
« Reply #5 on: October 23, 2021, 01:13:27 AM »
I don't believe the stepper motor itself should be grounded
Perhaps the warning is telling you it's grounded when it shouldn't be, English can be quite ambiguous at times. Don't take my word for it though.
Actually Guzzidiag has a routine for testing the stepper.
« Last Edit: October 23, 2021, 01:21:25 AM by Kiwi_Roy »
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Offline lucky phil

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Re: Stepper motor ground issues
« Reply #6 on: October 23, 2021, 11:34:18 PM »
I don't believe the stepper motor itself should be grounded
Perhaps the warning is telling you it's grounded when it shouldn't be, English can be quite ambiguous at times. Don't take my word for it though.
Actually Guzzidiag has a routine for testing the stepper.

Some stepper motors are actually earthed through the ECU. No separate stand alone earth connection.

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Offline muddyjwj

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Re: Stepper motor ground issues
« Reply #7 on: October 24, 2021, 01:59:17 PM »
Thanks so much guys. Yes, found no direct connection to ground. All 4 wires from stepper connector go to the ecu. Could be open or short as you say. Thanks also for the heads up up on Guzzidiag. I guess it is time to pull the trigger on some cables and download the software. I found a replacement stepper motor for about $400.00 just as Guzzisteve said but there was no image or any way to tell if in fact it is the newer plastic motor. I'll give them a call tomorrow to confirm. As the metal motors seem to be problematic, I may just get the newer plastic one to keep on the shelf....
Thanks again guys!

Offline tris

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Re: Stepper motor ground issues
« Reply #8 on: October 24, 2021, 02:06:44 PM »
If the ECU is in the same place on the Stelvio as it was on my old Breva 1100 the connectors are a mare to get plugged back in

I managed to bend one of the pins through 90 degrees refitting the plug, so worth checking if you haven't already since the issue arose

The good news is that I managed straighten it up and normal service was resumed
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Offline muddyjwj

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Re: Stepper motor ground issues
« Reply #9 on: October 24, 2021, 02:50:36 PM »
Thanks for the advice. You are absolutely correct about plugging in the ecu. I did pull the rear brown connector from the ecu to check the pins. I almost wish I did find one bent. At least then I would know what the problem was. I found the trick is to GENTLY pull the top of the ecu away from the fairing while easing the connector in place. The ecu has a little play. Helps with 2 people..   That said all looked perfect. The only thing I noticed was a tiny flake of derbies that I removed with a bit of compressed air. I Gave the pins a shot of contact cleaner, buttoned everything back up and turned on the key. Immediately the red light came on and I still have the code. I might add that no matter what I do, even disconnecting the battery I cant delete the code... Oh, and the bike runs like sh_t  and sucks up gas like nobodies business. After giving it a little more thought, it seems I have had a rash of different codes lately. Maybe time to suspect the ecu??
There is a race shop about an hour away that specializes in Ducati and  Magneti Marelli ecu electronics. They also mention Moto Guzzi on their web site. If all else fails I'll trailer the bike to them.

Offline muddyjwj

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Re: Stepper motor ground issues
« Reply #10 on: October 27, 2021, 08:42:57 PM »
I just read something interesting on the Guzzitech site. Someone over there was receiving the same error 62 code and it turned out to be a clogged stepper motor due too filling the crankcase up to the full mark. The breather was pulling oil mist into air box and stepper motor. Ive heard of this before and recently after having a tire replaced I got lazy and let the shop change my oil. Sure enough I noticed oil all over the bottom of the air box. I am hoping that I have the same issue. The guy went through a ritual of using carb cleaner, silicone lube and seafoam at different intervals over a couple days of riding and finely got the stepper motor working again. Code gone and no more service light.
I don't remember what 8V bike he had but he was able to access the hose from the air box to the stepper motor and use it to spray the above cleaners and lube directly into the stepper motor with the engine running. On my Stelvio (small tank) the hose is in the shape of an upside down "U" directly behind the battery. The only way I can think of to accomplish introducing cleaners into the stepper motor and still be able to start and run the bike would be to pull the battery, install a tee into the existing hose  (as others have done) and attach a short hose and valve. Good project for tomorrow. Hopefully this will solve the problem. I'll keep everyone posted....

Offline muddyjwj

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Re: Stepper motor ground issues
« Reply #11 on: October 28, 2021, 05:18:06 AM »
If it is the stock metal body stepper best replace with newer plastic one. Check which one you have.
The service manual tells you which pin is ground, look it up & clean pins.

The stepper is in the center of throttle body rails.
Steve,
How would I go about replacing the stepper motor if need be? I am going to go ahead and buy a new one while they last at the $350.00 price as I have seen them for just south of $800.00. Unbelievable! Anyway I was wondering if it is possible to replace the motor without removing the throttle bodies. It looks like it might be possible by just removing the tank and battery box. Removing the tank is doable but I'm not sure my skill level is up to fooling around with the throttle bodies. Noticing oil in the air box and reading where another Guzzi owner was getting the ecu 62 code due to a gummed up stepper motor, I am leaning toward a stuck stepper motor as the cause of the rough running engine and the service warning/ecu code and not an electrical problem.

Offline Kiwi_Roy

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Re: Stepper motor ground issues
« Reply #12 on: October 28, 2021, 05:51:57 AM »
I presume by now you have dropped the oil level down below the half-way mark on the dipstick?
I remember asking why we even need the oil breather to return over-levels of oil back into the breather box where all it does is gum up the throttle bodies, all I got was grief for asking?
It should be possible to remove the stepper motor input from the airbox and route it to a spot where you can spray throttle body cleaner into it. and remove it from the source of oil.
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Offline tris

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Re: Stepper motor ground issues
« Reply #13 on: October 28, 2021, 06:58:36 AM »
Steve,
How would I go about replacing the stepper motor if need be? I am going to go ahead and buy a new one while they last at the $350.00 price as I have seen them for just south of $800.00.

That's a bugger, I sold my spare as I don't have the B1100 any more for 45 quid only last week!

Look for the Ducati version too as its the exact same part

I also put together a little circuit that would stroke the ICV on the bench. If you're interested let me know and I hunt down what I used
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Offline muddyjwj

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Re: Stepper motor ground issues
« Reply #14 on: October 28, 2021, 11:16:05 AM »
Thanks guys,

Yes I did check the oil level. Just about mid level if the dip stick isn't pushed all the way home. I also removed the hose from the air box to the stepper and connected a longer hose directly to the stepper. I re-installed the battery box and battery then started the engine and gave it a good shot of carb cleaner. After doing this several times the engine began to run much better but that may just be due to the engine reaching operating temp. The code is still there and can't be deleted via the dash diagnostics. Will try again alternating between seafoam and carb cleaner. I looked at an Aprilia stepper but it looked different than the one on my Stelvio. Anyway I need to find out if the stepper replacement project is above my skill level. If so I will need to get the bike to a non Guzzi shop. They are a Ducati race shop that says they specialize in Magneti Marelli so maybe, just maybe they won't do more harm than good as all the other approved and non approved service shops I have been to did. That's why I want to do this myself if at all possible and if necessary.



Offline muddyjwj

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Re: Stepper motor ground issues
« Reply #15 on: October 28, 2021, 11:19:42 AM »
That's a bugger, I sold my spare as I don't have the B1100 any more for 45 quid only last week!

Look for the Ducati version too as its the exact same part

I also put together a little circuit that would stroke the ICV on the bench. If you're interested let me know and I hunt down what I used
Thanks tris! that would be great...

Offline guzzisteve

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Re: Stepper motor ground issues
« Reply #16 on: October 28, 2021, 12:11:58 PM »
The tank w/wraparound bodywork is no fun. You can slide the airbox back off, only a few bolts on the back part. The rubber intakes will squeeze together and slide past frame if you wiggle clamps out 1st w/o bending them up. You had batt box out aready, not too bad to get in there. A friend of mine got rid of his altogether. He uses a feeler gauge behind the TB stop till it'll idle w/cold.
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Offline muddyjwj

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Re: Stepper motor ground issues
« Reply #17 on: October 28, 2021, 01:57:37 PM »
Thanks Guzzisteve!
Will order the new motor next week (after pay day). In the mean time I'll continue to try and revive the old one. So with the airbox removed I'll be able to fish the stepper out and around the throttle body bracket?

Offline tris

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Re: Stepper motor ground issues
« Reply #18 on: October 28, 2021, 03:21:27 PM »
Thanks tris! that would be great...

You need one of these  https://www.ebay.co.uk/itm/4-Wire-2-Stage-Stepper-Motor-Driver-Adjustable-Speed-Controller-Remote-Control-/292420605095?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=710-127635-2958-0

Replacement plug for a ducati stepper  - I can't find a link for that at the moment

A chunk of cable with a USB connector one end - from a dead set of headphones for example

USB charger

Solder it all up as needed and away you go stroking steppers on the bench


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Offline muddyjwj

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Re: Stepper motor ground issues
« Reply #19 on: October 29, 2021, 02:41:00 PM »
You need one of these  https://www.ebay.co.uk/itm/4-Wire-2-Stage-Stepper-Motor-Driver-Adjustable-Speed-Controller-Remote-Control-/292420605095?mkcid=16&mkevthttps://wildguzzi.com/forum/Smileys/default/angry.gif=1&_trksid=p2349624.m46890.l49286&mkrid=710-127635-2958-0

Replacement plug for a ducati stepper  - I can't find a link for that at the moment

A chunk of cable with a USB connector one end - from a dead set of headphones for example

USB charger

Solder it all up as needed and away you go stroking steppers on the bench



Thanks Tris,
Looks like what I need for sure but I'm not so sure how to hook it up and use it.  I will need a little more detail to put it to use.   That said I haven't been successful in reviving the original stepper motor  and I am not so sure I will. The error code was at first intermittent but suddenly flashed on continually so I think the solenoid may be shot (shorted to ground). I just called Harpers to purchase a new motor, but as luck would have it the $350.00 motor is no longer available and the new part is almost $800.00. THAT IS INSANE! There is no way in hell anyone can justify that kind of money for a simple solenoid needle valve.

 So, I saw your reference to the Ducati stepper being the exact same motor. Is it indeed  exactly the same and does anyone know if it is compatible with the ecu mapping on the Stelvio? In other words, is it "plug and play"?  If so, that will solve a lot of problems as I also want to order your Ducati tickle kit to try and revive my Moto Guzzi stepper motor.  We are 110V 60 Hz over here if that makes any difference. (I noticed the European plug in the photo). 

Offline tris

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Re: Stepper motor ground issues
« Reply #20 on: October 29, 2021, 03:47:38 PM »
I'll try and find out how I created the little circuit, but its a loooong time ago now!

Also I think this is the plug for the testing circuit
https://www.ebay.co.uk/itm/192918849926?hash=item2ceadc0986:g:Z9QAAOSw1chc3b06


Re the Ducati stepper itself

Firstly understand that its a simple little motor driven valve that does what its told to do by a signal coming from the ECU
Whether that is a 5AM ECU in a Ducati or a 5AM ECU in a Moto Guzzi it neither knows nor cares

Type "Ducati Stepper" in your favourite search engine and and look at the images where you'll  find a load of pictures most of which are the same as the MG ones.

Ignore these later ones
https://www.kfm-motorraeder.de/cms/en/genuine-spare-parts/ducati-spare-parts?itemid=28340201A

They mount the same but the single port is bigger. However, they changed the stepper motor mounting itself so that you could replace it on its own without the complete body!!!

This is the beastie you're looking for
https://www.carousell.sg/p/ducati-oem-streetfighter-stepper-motor-195115514/

Part No. 28340241A

At random, this lot stock them. https://amsducati.com/ducati-oem-stepper-motor-10399

PS

If you haven't already it would be worth checking to see if any of the leads from the stepper short to earth by putting a meter across them as it might save you the cost to the valve
If you're not sure how to do it I'm sure Roy could guide you as to the best way

« Last Edit: October 29, 2021, 03:59:55 PM by tris »
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Offline muddyjwj

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Re: Stepper motor ground issues
« Reply #21 on: October 29, 2021, 08:55:36 PM »
Thanks ever so much Tris!

I was thinking the same thing with regard to checking for a direct earth ground. I may take a day or so to step away from the Guzzi and catch up on some much needed lawn work (and to provide a little TLC to my R1250GS). That said I am beginning to think that the solenoid winding in the stepper may be shorted. This would make sense as I am getting a ground fault code. I wish I knew what resistance I should be reading across the stepper pins.  Next step will be to check continuity from the ecu to the stepper connector and then for any shorts to earth ground.

Offline tris

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Re: Stepper motor ground issues
« Reply #22 on: October 30, 2021, 12:28:01 AM »
My stepper knowledge has faded somewhat since I last messed about with these, but I think that if you look at the wiring diagram you'll see the wires to the stepper labeled A1, A2, B1, B2
On the stepper there should be continuity between the As or between the Bs but not between an A and a B
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Offline muddyjwj

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Re: Stepper motor ground issues
« Reply #23 on: October 31, 2021, 09:59:29 AM »
Thanks again my friend! That helps...

Offline muddyjwj

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Re: Stepper motor ground issues
« Reply #24 on: November 12, 2021, 03:27:38 PM »
Update,

Checked the manual and wiring diagram and found ecu pins 9,17,18,and 19 are the stepper connections. I checked for continuity and sure enough pins 9 and 19 are shorted to ground. Now I'll have to pull the tank and find the short.  I'll order the stepper driver as well so I can bench test it while I'm at it.

I'll keep everyone posted so if anyone else has a similar issue they will have an idea where to look.

Offline tris

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Re: Stepper motor ground issues
« Reply #25 on: November 14, 2021, 01:13:46 PM »
Look what I've found Muddy





Double check the wiring though, I don't want you to blame me if you fry the stepper  :grin:
2017 V9 Roamer
2005 Breva 1100 (non ABS) "Bruno" - now sold
1995 Cali 1100 - carby   "Dino" -now sold
1993 TW125 "POS" - Resting

Offline muddyjwj

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Re: Stepper motor ground issues
« Reply #26 on: November 21, 2021, 09:51:07 PM »
Well,

I pulled the tank and the fairings and checked the loom from the ecu to stepper plug and found nothing suspicious. The harness looks good. No cuts or chafing anywhere. With the stepper removed and the harness disconnected at both ends I checked again and I was shocked to find the short was gone. I tried wiggling the harness and the connectors and could not get the short to return. I also checked the stepper motor and it checked out electronically.  About 50 ohms on each coil and no short between the two coils or to the case.  I had checked the harness before pulling the tank with the stepper disconnected and very definitely had a sort to ground on both pins 9 and 19.   Go figure!

I'll start buttoning everything back together  and we'll see what happens...

Offline muddyjwj

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Re: Stepper motor ground issues
« Reply #27 on: November 21, 2021, 10:47:39 PM »
Tris,

Thanks so much! Sorry I missed your post. Been away for a while taking care of my parents.

I ordered the one you posted earlier last week. Total cost including shipping across the pond was only about 10 bucks U.S. Ordering just the plug from the U.K. will be $70.00 U.S. for shipping alone! There must be a cross reference here in the states.

To be honest I think the stepper is OK and the problem was the short between pins 9, 19 and earth ground. I believe it may have been due to  an abundance of deoxit contact cleaner in the connector. Unlike other contact cleaners deoxit contains a lubricant that leaves an oily film. Only theory I can come up with is once the connector was left unplugged for a while the stuff dried/drained out and the short disappeared.

Checking the wiring is no issue but I don't want to overload the stepper by applying too much voltage/current. When you used it how did you determine the proper voltage/current to avoid overloading the coils in the stepper?

Offline tris

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Re: Stepper motor ground issues
« Reply #28 on: November 22, 2021, 01:20:15 AM »
I too have been dealing with older relatives who live at the opposite ends of 150 mile sided triangle from me so I know the difficulties that brings!!

Re the stepper first thing to know is that it does NOT use the 12v supply on the bike - you put that across the stepper coils and you'll definitely fry it

If you look at the picture you'll see a USB connector. I just used a suitable phone charger with a USB connection as they output 5v and that worked fine

But first things first, check for continuity (in the right places) across the stepper coils as discussed earlier. If that's not right then there is no point in trying to stroke the valve





2017 V9 Roamer
2005 Breva 1100 (non ABS) "Bruno" - now sold
1995 Cali 1100 - carby   "Dino" -now sold
1993 TW125 "POS" - Resting

Offline muddyjwj

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Re: Stepper motor ground issues
« Reply #29 on: November 23, 2021, 06:59:06 PM »
Hi Tris,

Yes, caring for the folks is tough especially when they live so far away. Only 70 miles 1 way for me but the traffic makes it a 2 hour drive... I often take the scenic drive out to and through the Fla. Everglades. It adds 30 miles to the trip but there is no traffic so it takes the same amount of time with less headache. Just need to keep an eye out for alligators at night. Hitting one of the big ones is like hitting an oak log and it makes em angry as hell!!!

I was really tired when I got home but I couldn't resist so I bolted the stepper into the throttle body, plugged it in to the harness and and checked the 4 pin sockets at the ecu connector. Everything checks out! Pins 9 and 19 have continuity through 1 of the stepper coils with about 50 ohms. Pins 17 and 18 have continuity with 50 ohms through the other coil. None of the pins have continuity to earth ground and neither coil has continuity to the other. I really think the short was caused by the contact cleaner in the ecu connector...

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