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MG MGB Technical - Electrical Problem

1968 BGT, returning from car show today when suddenly tacho, and other gauges shut down as well as electric fuel pump, which stops working, leaving me stranded on side of road. I have power to starter and lights and horn work but no blinkers or wipers.Checked all connections under dash I could get my hands on but all seem well.
Checked connections at ignition switch too.
BTW, Coil seems very hot to the touch (normal?).

Heres the rub...As I keep trying ignition, every once in a while things will work. Fuel pump starts pumping, gauges work, car runs...but only for a few seconds, then things shut down again all at once.

Had a couple of club members come by to help but left us scratching our heads.
Called tow truck and she sits in driveway waiting for Plan B

Any help?
Dennis Silance

Is this a two fuse fusebox or four fuse fusebox?

M Whitt

Wiring diagrams are available at

Make yourself a couple of enlarged copies, one for reference and one to make notes on as you check things out.

The one thing everything you mentioned not working has in common is the white wire from the ignition switch.

Mark, two fuses in box.

Kim, great diagrams! We suspected ignition switch, tho connections are sound, it could be the switch itself.
Have to start tracing and testing this morning I guess.
Dennis Silance

Does power to the starter mean it gets there through the start position of the ignition switch? If yes, connect a jumper wire from the brown wires to the white wires at the fuse box. If it run the problem should be in the switch or white wiring between the switch and fuse box. Near the fuse box is a bundle of connectors, locate the one with white wires and check the condition of the connector and check for 12 volts on the white wires. Coils do get rather hot, it's probably normal.

Clifton Gordon

With ignition turned on, multi-tester shows no voltage reading at white wire at fuse box.
When I connect jumper wire from brown to white at fuse box, it works. All gauges and fuel pump come back on.
Ignition switch?
Dennis Silance

Dennis: Check for 12 volts at the white wire on the ignition switch, if you don't have it there the switch should be your problem. If you have 12 volts out of the switch the problem is in in the connector at the switch or the white wiring circuit between the switch and the connector for the white wires near the fuse box.

Clifton Gordon

It was as you suspected, in the white wiring circuit between the switch and the fuse box.
Cleaned spade end at fuse box and connectors(2) in white circuit and coated with dielectric grease!
Don't know exactly which one was the culprit but no matter... All three can share the blame.

Thanx for the input
Dennis Silance

DS; It's good to hear you have it going again and didn't have to replace the switch.

Clifton Gordon

This thread was discussed on 09/07/2006

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