Ignition light comes on when there is no key in the switch

General MGB discussion
User avatar
Michael Barclay
Posts: 100
Joined: Tue Dec 06, 2016 8:05 pm
Forename: Michael
Surname: Barclay
Location: Abingdon

Re: Ignition light comes on when there is no key in the switch

Post by Michael Barclay »

Hi Charles
Totally agree with your comments. I’m sure that many of the problems are caused by PO’s messing with wiring and that if the car in question was physically in front of us, any problems could be easily identified. MGB electrics are rudimentary so electrical problems should be fairly easy to resolve. BL made so many change to the electrics on RB cars, so part of the difficulty is working out which circuit diagram to use when identifying problems.
The relay you are referring to is below. The feed that would normally come from the starter motor to the coil during starting could be replaced with a wire from terminal 87B on the relay.
Regards
Mike Barclay
mgb relay (4).pdf
(212.51 KiB) Downloaded 12 times
Not_Anumber
Posts: 95
Joined: Tue Sep 22, 2020 9:33 am
Forename: Chris
Surname: Silk

Re: Ignition light comes on when there is no key in the switch

Post by Not_Anumber »

Hi Charles, i see what you mean. Yes, better to run that from a seperate relay.
User avatar
Charles Farran
Posts: 359
Joined: Fri Oct 31, 2014 11:08 am
Forename: Charles
Surname: Farran
Location: Warwickshire

Re: Ignition light comes on when there is no key in the switch

Post by Charles Farran »

Chris,
It utilises a separate tag on the relay that is only used during cranking which when not being used isolates it from the coli & hence stops a full 12V being sent when not required to a ballasted coil designed for continued running at the 6V range.( Should protect the starter motor & solenoid as well).
Cheers,
Charles
1980 Roadster
Post Reply