Stepper Motor Cycles on and off

Hi Guys

So I've had my GRiSO 1100 for about 2yrs now. Awesome machine and I love it to bits.

However, I have had an issue from the day I bought it with the stepper motor. The stepper motor cycles on and off after the ignition is turned off. This invariably flattens the battery. In my ignorance early on, I bought a new battery, saw that go flat, got a trickle charger..... eventually killed the battery...... I'm now looking to buy my third battery and have decided that I have to get my act together and resolve this stepper issue.

Firstly, is this a known issue? I've searched the net and find all sorts of stepper motor issues, mostly to do with the function of the Stepper motor. Not my issue. Everything runs fine except for this.
2. There is no Dash or ECU error showing on the on board diagnostics.
3. from some research, it appears that I can do away with the stepper, but this may cause a dash error.

Any informed advice or information would be greatly appreciated.

Cheers John

Interesting. The stepper is driven from the ECU only. There shouldn't be any drive signal with the key off.

When you switch the key to 'on', does the fuel pump prime?

OK, first thing to check is the ECU connectors. Disconnect the battery, pull the ECU and disconnect it. Both sides. Check them for crap. With the ECU disconnected, reconnect the battery. Do not switch the key on. Does the stepper still cycle? Disconnect the battery before reconnecting the ECU.


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beetle wrote:

Interesting. The stepper is driven from the ECU only. There shouldn't be any drive signal with the key off.

When you switch the key to 'on', does the fuel pump prime?

OK, first thing to check is the ECU connectors. Disconnect the battery, pull the ECU and disconnect it. Both sides. Check them for crap. With the ECU disconnected, reconnect the battery. Do not switch the key on. Does the stepper still cycle? Disconnect the battery before reconnecting the ECU.


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Thanks Beetle

1. fuel pump primes ok.
2. ECU connectors look ok.
3. Stepper does not cycle with the ECU disconnected and the battery reconnected.
4. Everything reconnected, ignition on, Stepper starts cycling again.

I just noticed that when the ignition is switched on the stepper doesn't cycle, but starts cycling when I switch the ignition off.

It might be worth nipping over to WG and asking this question. I seem to remember someone there had an identical issue a few years ago, might even of been Wayne Orwig, I believe it was resolved but can't remember how.....

Pete

Thanks Pete

Shall try that.

Caedmon wrote:

I just noticed that when the ignition is switched on the stepper doesn't cycle, but starts cycling when I switch the ignition off.

It's normal for the stepper to move to the 'home'(?) position when you switch the key off. It must function ok when the engine is running, otherwise your idle would be erratic.

Curiouser and curiouser.



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Yeah. It bugs me I can't remember what the endgame was on the last bike. It might of been something weird in the earthing but I really can't remember. It was certainly an odd one and when it was resolved I can remember thinking "Well, that had me buggered!"

Pete

beetle wrote:

Caedmon wrote:

I just noticed that when the ignition is switched on the stepper doesn't cycle, but starts cycling when I switch the ignition off.

It's normal for the stepper to move to the 'home'(?) position when you switch the key off. It must function ok when the engine is running, otherwise your idle would be erratic.

Curiouser and curiouser.



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Yeah, the whole bike runs great until I switch off the ignition.

I'm just registering at Wild guzzi to ask the question there.... Bit of a process, it's like trying to enter fort knox

Yeah, there are also some terribly cranky 'Old White Men' and more than a few dipshits over there but it's one of the biggest Guzzi sites in the world and seems to get hacked a lot so the registration process does seem a bit Byzantine at times.

A lot of the people who made it an fun place a decade ago are no longer there, (Our own Bill Hagan is a prime example.) and I've got so shitty I've taken several sabbaticals because of the idiocy and trolling but as long as you're selective and have a thick skin it is still both a useful resource and can be fun. There are some seriously skilled people who post from time to time.

Pete

I found this reference to the problem on Wildguzzi.

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Brian

Wet speedo sensor?




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GR1064 wrote:

I found this reference to the problem on Wildguzzi.

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Brian

Thanks Brian

There's no issue with my speedo sensor, or anything else that I can place. ..... suggests some electrical fault though....

Might try searching Guzzitech.

What if I put a switch between the ecu and stepper? Just to kill power to the stepper when the ignition is off. I know this doesn't fix whatever the issue is, but is it a feasible work around if I can't find any other solution?

Yes, it would work. As you say, it's a kludge.


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It will actually throw an error because the ECU can no longer "see" the stepper. But hey, what the heck do I know. You need to do what you can to isolate the problem, anything is worth a try.

OK, I looked at the circuit diagram for the 1100.

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If power is driving the stepper motor from the ECU with the ignition off, it could be coming via a faulty Main Injection Relay.  To test this theory, pull fuse 'D'.  IF I'm correct the stepper will stop??  Then check the actual relay, it may be stuck closed.

It may be a red herring, but nothing lost.

Brian

No, the stepper is only connected to the ECU.

Beetle, the way I think the power is going to the stepper motor is from the Battery to Fuse D to Main Injection Relay to ECU to Stepper Motor.  So if Fuse D is disconnected there is chance that the circuit will be broken.

Obviously the ECU is acting weird if it's powering the stepper motor with the ignition off, so doing this is worth a try.  The ECU could be in an invalid state if it's being powered via a faulty main injection relay with the ignition off.

Brian

GR1064 wrote:

Beetle, the way I think the power is going to the stepper motor is from the Battery to Fuse D to Main Injection Relay to ECU to Stepper Motor.  So if Fuse D is disconnected there is chance that the circuit will be broken.

Obviously the ECU is acting weird if it's powering the stepper motor with the ignition off, so doing this is worth a try.  The ECU could be in an invalid state if it's being powered via a faulty main injection relay with the ignition off.

Brian

So I pulled Fuse D and the stepper continued to cycle. Disconnect the battery and the cycle stops. reconnect and it stays stopped until the ignition is switched on then off.

AaaaaahhhhHHH!!! .....

Right. Pull fuse 'E' in your auxiliary fuse box. If the stepper stops cycling, you may have an internal ECU fault.

beetle wrote:

Right. Pull fuse 'E' in your auxiliary fuse box. If the stepper stops cycling, you may have an internal ECU fault.

Pull Fuse E and the stepper stops dead mid cycle. I do not currently know how I feel about this with mention of a ECU fault.....

Another thing. The 1100 wiring diagram shows an external capacitor tied to ground on the permanent supply (fed from fuse 'E'). They call it a presetting condenser. It doesn't exist on the 8V, so I can't tell you where it is or if it actually exists. It is possible that if it's leaking to ground, the voltage may never reach the level required to latch whatever is in the ECU to switch the stepper off. It apparently has a connector, so if you can locate it, disconnecting it might solve your issue.


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beetle wrote:

Another thing. The 1100 wiring diagram shows an external capacitor tied to ground on the permanent supply (fed from fuse 'E'). They call it a presetting condenser. It doesn't exist on the 8V, so I can't tell you where it is or if it actually exists. It is possible that if it's leaking to ground, the voltage may never reach the level required to latch whatever is in the ECU to switch the stepper off. It apparently has a connector, so if you can locate it, disconnecting it might solve your issue.


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I will have a look for this tomorrow night and we shall see.

I very much feel like progress has been made here. Pulling Fuse E will at the very least stop the battery from getting such a hiding. I don't think I really want to wear the $$$ on a new ECU if I can avoid it.

I really am grateful for the help

I've checked on my 1100 and have found the connector for the capacitor, it's located near the stop light behind the fuse box, but there is no capacitor fitted.  I sure it's the one, it's the correct wire colours and I measured 12V across the contacts with the ignition off.

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It appears MG deleted the capacitor early on, since my 1100 was built in 2005 and I've owned it since new.

The ECU is looking suspect.  The only other thing I can think of to check at the moment is the Earth connection to the ECU, both visually and with an Ohm meter for continuity to Earth (Frame/Battery negative).

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Brian