Electrical problem

[Nickhughes]

My 1988 crossflow engined car has the following problem. Start car and ignition warning light goes out then as revs increase light comes on. Sometimes after driving for a while it starts to, or does go out. Sometimes when indicators are turned on red light flashes also. Alternator is charging. Have recently put rebuilt engine back in car and changed to " Lucas Style Electronic Ignition. " from original Lucas points distributor.

[Jonathan Kay]

Private Message sent.

[revilla]

Possibly failed diodes in the alternator rectifier pack. It leaves it charging over part of the cycle only, which means it still looks like it is charging on a simple multimeter voltage check but it still pulls current through the warning lamp on the parts of the cycle where it is not charging. You would only see this with an oscilloscope, where you would see it charging in pulses.

[Nickhughes]

Light now staying on all the time.

Votage at rest is 12.70 volts

Minimum when cranking is 10.2

At Idle 12.4

at 3000 rpm 14.6

This is from cold engine.

[revilla]

I'd get the alternator serviced. It may be repairable. If not, replace it. There's not really anything that could be giving those symptoms that's not inside the alternator.

[Nickhughes]

Will order new alternator ( it is 34 years old). Thank you for the help