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MG MGB Technical - Stopped running,can't start...

This seems to be a common problem but each case a little different... I was running the engine the other day to warm it up. It sounded great and all of a sudden the engine just stopped running. I couldn't restart it. Not a red ignition light or a click or anything upon trying to restart it. I checked and coated all the battery connections but all that works are the headlights and the hazard warning lights. Does anyone know where this problem is? 74' MGB (2 6V batteries) - Thanks.
Brian

Brian. You have already diagnosed your own problem--something is preventing power from going through the non-full time circuits (brown wire circuits). Get a copy of the wiring diagram for your car, have it blown up about 300% then laminated. Use the expanded diagram to start tracing power from the brown wire circuits to the ignition switch. You should find your problem in that area. Les
Les Bengtson

Brian, Which electrical components are working or is everything dead? If everythng is dead check the thick brown wire on the starter solenoid. Make sure the spade on the wire has a good connection to the solenoid spade. Not all starters have the spade and some will have the heavy wire attached to the battery cable post on the solenoid, either way the connection should be clean and tight. If you do have 12 volts on the brown wires at the fuse box you will find the start relay to the left of the fuse box. MAKE SURE THE CAR IS IN NEUTRAL, hand brake on, remove the yellow/pink wire from the start relay and connect a jumper from the brown wires at the fuse box to the relay spade you removed the Y/K wire from, if the starter now turns the problem is in the wiring/sequential seat belt circuit/ignition switch. I would check the ignition switch first as you have no ignition on light and it doesn't go through the sequential circuit. Good luck, Clifton
Clifton Gordon

Well, I do know that before I bought this car that the ignition switch had been recently replaced. It seems like I really need to trace the brown wire from the switch. Your input is a great help, thanks.
Brian

Brian. It sounds like the problem is between the starter solenoid main terminal and the ignition switch. With an enlarged wiring diagram, the one which has been laminated, I take a Vis-a-Vis marker (washes off with water) and trace the circuits involved back to a common point. Then, I begin my checks there. When you find power, then find no power later in the circuit, you know where the problem is and can correct it. Les
Les Bengtson

A 74 should have a single brown coming up from the solenoid to a sealed junction, and from there to the light switch, hazards, ignition switch, main lighting switch, fusebox and starter relay. If the headlights still work, including when you turn on the ignition, then the wire up to the sealed junction must be sound and I have never known of that junction to fail. The most likely place is the ignition switch or the multi-way plug where it and the white conenct to the main loom.
Paul Hunt

This thread was discussed between 07/07/2004 and 09/07/2004

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