Triumph Repair: TR6 Electrical questoin, bright sun light, pencil lead

Question
Dear Howard:
My tr6's blinkers stopped working and radio light was intermittent and when I stopped the car I could not restart it as if there was a short or the battery was dead....your thoughts?
Thank you Jim Della Croce Northeaset PA

Answer
Hi Jim,

When you have several electrical problems it is 100% a waste of time to try to use symptoms to diagnose the problem. All that the symptoms tell you is that you have an electrical problem in several circuits.

The ONLY method to correct the problems is to test. When you have several circuits that are faulty, you need to pick one and only one of the circuits to test. I found that by following a single circuit starting at the "Load" (item that don't work) and with a wiring diagram in front of you and a test light, test for power and a good ground at the Load. (It is best to pick a simple circuit of the failed circuits) For example it is more difficult to use a failed wiper circuit because it has more then one power supply so you would be tracing down several branches to find a fault.

In your case you have an engine that don't start and turn signals that don't work. The engine not starting is probably the easiest to test.

First you must confirm that you have a fully charged battery. (12+ volts) then after you have a fully charged battery see if the starter spins the engine over fast. If it does and the engine does not start, you have divided the circuit in half already. The starter circuit is ok if it spins the engine so proceed to the ignition.

Remove a spark plug and put the wire on the plug and lay the plug on a metal part of the engine and have someone spin the starter while you watch the spark. You want to see a thick (thickness of a pencil lead)and the color should be blue. (not in bright sun light)

If there is no spark or a hair thin spark that is yellow or orange color, the spark is weak and probably will not start the engine.

If after charging the battery, starts and runs again, you must do another test. You will need a volt meter to check battery voltage with the engine off. (12+ volts) then restart the engine and set the RPM on about 1500 RPM and read battery voltage again. It should read 13.8v to 14.5v if the charging system is working.

Most of the time when you have several failed circuits and you correct one, it will usually correct all the other failed circuits.

Let me know what readings you get and if you do not have a wiring diagram let me know and I will post one on my web site for you to copy.

Howard