Hi - -

Been having an issue w/ my '68 280s where the engine kills when the brake is applied. There seems to be no mechanical issue, the motor smoothly quits and the red 'warning' signal illuminates as her driver tries to find a place to make a smooth landing.

After quitting the car restarts immediately, but dies under the same initial brake pedal application a few times before this problem goes away. I have found that if I restart the car as the turn signal is being applied, the restart issue problem is alleviated. I'm thinking a loose or disintegrating ground wire someplace. Any ideas?

Thanks!

Brake operation causing engine to die -
most common cause is faulty power brake booster causing massive vacuum leak when brakes are applied.

If you're convinced it's electrical, does it die anytime you apply the brake or only when the car is moving? If only when moving, look for some inertia-related problem - coil wire, engine ground or battery shifting when you slow down.

If you don't find any visible problem, you could try connecting a 12 volt test light between the coil positive and ground, with enough wire to be able to place the test light so you or an assistant can see if you lose power when you brake.

If the coil positive tests OK, repeat the test using a dwell-meter on the negative/points side of the coil.

If you can duplicate the problem with the car stationary and the hood open, these tests will be easier. Good luck.

Happy Motoring, Mark

__________________
DrDKW

My spontaneous loss of ignition problem is very sporadic, occuring more frequently after the car has sat for a week or two. I have produced the problem most often during warmup idle, with the engine killing when the brake pedal is depressed, or turnsignal activated, horn button pressed, etc. The problem seems to occur much less frequently when the car is taken out and driven regularly.

Coil, wires and plugs have been replaced recently...

I'm guessing the brake booster is not the problem as brake function is retained when the motor kills. I assume a vacuum leak at the brake booster would be very audible, and I'm hearing nothing out of the ordinary (besides "OH #@*&).

Anyway, the help is much appreciated. Thanks.

Go ahead and check for loss of voltage at the coil positive terminal. A voltmeter here would be more accurate than a test-light. With the ignition key on and the points closed you should read something in the range of 5 to 7 volts. See what happens when you hit the brake, signals, etc...
There could be a fault in the ballast resistor or ignition switch.
If voltage readings are OK, I'd start looking for a grounding problem.
I don't think the '68 had the transistorized ignition unit but if yours does, that could open another can of worms.

Happy Motoring, Mark

__________________
DrDKW