Hi Guys ive bought my son a sinclair like me wee we love 3 wheels.
I have a problem,and we are new to these.
my son uses his C5 all the time but tonight on his return journey home,he informed me that when the c5 ignition is switched to on it just goes..it tried disconnecting the go switch but still wants to drive when the key is turned on.
any tips would be great.

Hi there you may find that the relay contacts in the control box have welded themselves together ....Let me know I will be able to lend you a new relay to test it in the control box ....I will send you my phone number in a PM ...BYE Chas

Hi Chas I tried calling the number u gave me in the PM...???
07867910782

I had this problem, although it was intermittent. I unpluged and replugged everything, and that sorted it.

There's a good chance that either the relay contacts have been welded together or the return spring has snapped as both of mine had.

If the contacts have stuck together the only long term fix is to change it as the plating on the relay contacts will have been damaged (hence them having been able to weld themselves together in the first place). Plus side is that suitable relays aren't expensive.

Worth checking and/or changing D1 while you're in there. This exists purely to prevent excessive contact arcing when the power to the motor is cut, failure of which is probably the main reason for contacts sticking.

The thing to remember about D1 is that it is connected backwards across the motor, so if the C5 is pushed backwards too quickly the motor acts as a generator and will shove a large amount of current through the diode and cook it. C5 will still work fine in this situation until the relay croaks. So worth changing it as a precaution.

Sure it would be possible to engineer in a protection system to get around that...