QuestionQUESTION: My 77 b will start and run but you can not turn it off with the ig switch.
ANSWER: Hi Bill,
First does the engine run normally with the key off or does it die if you try to rev the engine or drive it? If this is the case you need to correct the anti dieseling system. (the small solenoid at the bottom of the charcoal canister)
If the car can be driven and it runs normally with the key off, run this test.
Remove the charge light bulb from it's socket. (Ign light) Start the car and turn it off. If that makes the engine turn off normally you will need to install a diode in the charge light circuit. (You can't just leave the bulb out as that disables the alternator.
If that does not correct the problem, you have a wiring, Starter relay or ignition switch problem and you will need to trace the ignition circuit with a wiring diagram and test light to find what is still powering the ignition system with the key off.
If you don't have a diagram, let me know and I will put one up on my web site for you to copy.
Howard
---------- FOLLOW-UP ----------
QUESTION: Thanks Howard the diode did the trick I can't find a wiring diagram that seems to be correct for this car If I could get one from you it would help as this has had shall we say some less than professional wiring work done on it.
AnswerHi Bill,
The diode was something we had to do to several MGBs of that area.
The diagram is on my site under http://mg-tri-jag.net/76MGB1x1.jpg
The index to the diagram is at http://mg-tri-jag.net/76MGB21x1.jpg and the added diagram to upgrade a 76 to a 77 diagram is at
http://mg-tri-jag.net/77MGBsup1x1.jpg
The 76 and the 77 B diagrams were the same except for the supplement diagram.
Howard
