Start maintenance relay

Trying to understand the starter circuit on my 1200, and have a question (Kiwi Roy, maybe..?): what's the purpose of the maintenance relay and how does it work?

The maintenance relay bypasses the ECU interlock once the Start relay has closed. As long as you hold your finger on the start button. As soon as you take your finger off then the ECU interlock is back in play.
I believe this relay was added to try and cure Startus Interruptus after they changed the wiring from the 1100 where the Start relay 30 contact is always alive to the 1200 where its fed through the ignition switch Fuse 2
I don't have a 1200 to try but I suspect you can remove the maintenance relay if the Start relay has the Startus Interuptus fix.
Please try unplugging the relay and report back.
It is possible that when they modified the wiring the ECU may have been dropping the start relay out due to low Voltage (too much loss in ignition switch and weak yellow wire) The maintenance relay would keep it cranking over if the Start relay dropped out.
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Early GRiSO with always alive Start Relay fed from fuse "C", no Maintenance relay
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Later 1200 GRiSO with Start relay fed through Ignition Switch and Maintenance relay
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Thanks for the explanation Roy, makes sense.
Not sure if I understand why they went from the set up of the 1100 to the one on the 1200 though, what could be the expected benefit?

I have done the Startus Interruptus fix, the short one.
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I'll try to disconnect the maintenance relay next time I'm at it and see what happens...

We were also discussing under another post whether or not it would make any sence to draw a direct cable from the battery (via fuse and relay) to the head lamp. Would it give any better light (and eventually put less strain on the switch)? Seems like the lights are fed directly from the switch, and the cables seem to be very thin...

bjor wrote:

Thanks for the explanation Roy, makes sense.
Not sure if I understand why they went from the set up of the 1100 to the one on the 1200 though, what could be the expected benefit?

I have done the Startus Interruptus fix, the short one.
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I'll try to disconnect the maintenance relay next time I'm at it and see what happens...

We were also discussing under another post whether or not it would make any sence to draw a direct cable from the battery (via fuse and relay) to the head lamp. Would it give any better light (and eventually put less strain on the switch)? Seems like the lights are fed directly from the switch, and the cables seem to be very thin...

I'm at a loss to explain Luigi's crazy wiring but I have to conclude they don't understand how the starter solenoid works, they never show both coils and the 15 Amp fuse would be about right for a circuit drawing 10 Amps, thats what you will measure once the dust settles if you put a meter in series Ohms Law and my oscilloscope tell me the fuse needs to be at least a 20.I have been studying this problem for at least 15 years.
I have tried to make contact with someone at Piaggio on several occasions however they are not listening, I doubt they know of these forums.
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I have added a pair of relays to several bikes, there's plenty of room in the headlight bucket for that. Sometimes you can use just one form C relay. Run either  the existing H/L wires to power up the relay coil, you will still need the existing headlight logic relay though, yes it will make the headlight considerably brighter.
Power up the relay 30 terminal from the battery through a fuse, You might also tap into the main feed at the ignition switch and take advantage of an existing main fuse at the battery (23), I no longer have a GRiSO so I'm not sure which of the two feeds from main fuses (23) is the beefiest.
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Another Option
A typical LED headlight will be at full brightness anywhere between 9 & 30 Volts so if you find a nice H4 LED headlight bulb and use the standard headlight wiring, you can afford to lose a volt or two in the wiring, it won't effect the brightness.

Very interesting Roy!
And good to know that if I don't always understand the logic of the wiring diagram, it's not necessarily something wrong with me...

I've also done the relay-conversion of the head light on most of my bikes, including my newly bought GRiSO. I made a topic on it in case someone else also wanted to do it (https://www.grisoghetto.com/t6491-headlight-via-relays).
However, we were not sure if it actually made any sence on the GRiSO, so thanks for clarifying that as well

I read somewhere that headlight brightness is equivalent to Voltage to the power of 5, I think it was saying an extra half a Volt has a huge effect. Anytime you can bypass the tiny wires to and from the dimmer switch its well worth doing. Using a relay will drop the current through the switch from about 4 Amps to around 100 milliamps. Another worthwhile project for a relay is the Horn, think about adding a horn relay if you don't already have one, you can use the same feed as the headlight relay, doesn't need its own fuse as its seldom used.