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TR 250 Generator Light Flashes on the Dashboard

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redbirds64 James S
Flora, IL, USA   USA
Any ideal why my generator light on the dash board flashes red every second while the car is running? Stepping on the gas does not change the frequency of the flash. This started this year after being in winter storage.

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LFMTR4 Lou Mijares
Scottsboro, AL, USA   USA
I’d say it is a rectifier problem. Take it to a FLAPS or alternator shop, they should be able to test it.

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dgetr250 Don Evans
Berea, OH, USA   USA
Can't solve your problem, but I'll lend you support: my light was on also. Years ago, it would come on after about twenty minutes of driving; then later it was on from the get-go. The ammeter always registered a charge and the battery did not run down. The oil pressure gauge always registered good pressure, so I was assured the previous owner didn't do the "race car trick" of wiring a big red low oil pressure light directly in his line of sight. When I get the car back from resto I'll hope the problem has gone away ... especially since I've gone to a GM alternator. Still have two OEM alternators to send out for analysis if I can find a shop that knows these things.

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TR3driver Randall Y
Confusion, Los Angeles, USA   USA
Check what the ammeter does when the light comes on; maybe flip on the headlights so you can see for sure if the alternator is still working. If so, it almost has to be a wiring problem.

My first thought would be the brushes and slip rings. Disconnect the wires and measure the resistance from (I think) IND to F. Should be between 4 and 5 ohms, with little or no variation as you turn the rotor, wiggle it, push in and out, etc. Wouldn't hurt to remove the brushes and do a visual inspection. My book says original length is 1/2", and there should be at least 0.2" protruding from the brush holder with it removed from the alternator. Also inspect the surface of the slip rings all the way around. A light brownish color (like an old penny) is OK, with some variation in color up to a newish penny. But blackened areas mean it needs to be resurfaced and attention paid to the brushes.

As a brief test, try pulling the connector off the regulator, and installing a jumper from the F terminal to ground. Start the engine briefly; if the light no longer blinks then most likely the regulator is at fault. You should also see the ammeter go to around +30, meaning it is overcharging the battery, so don't run that way for more than a minute or so.



Randall
56 TR3 TS13571L Once and future daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

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