alt. light dosent turn on

[santafe308]

my 79's alternator light used to come on when i turned the key then shut off once the motor is running. and at the time when the light did work the system would only seam to charge half ass and now that the light doesn't turn on what so ever the same thing still exists doesn't seam to charge consistently any ideas were to start checking?

[djape1977]

voltage regulator first, if it ain't broke than alternator

[FiatMac]

The alternator light is part of the circuit that provides field excitation for the alternator. If the light is burned out or the wire is disconnected, then the alternator will not work. Apparently the wattage of the bulb also has to be more than 2 watts for the excitation to work. I would check to make sure that the bulb is not burned out and that the wire is connected at the alternator as a first step.

[majicwrench]

Check your fuses....

[santafe308]

well i took out the alternator today and it was the bosch brand so i figure the PO must have upgraded. well all the wiring was connected im going to take the alt. down to autozone today and have it tested. and also check the bulb since i removed the alt. as it is taking it out gave me room to remove the old leaves out of the engine compartment and clean more things up.

[majicwrench]

Check fuses....check for power at proper terminals.. checking alternator off the car (for free) gives you very little good info. Good luck.
keith

[santafe308]

well i tested the light thats in dash on a 12 volt power supply its good so im going to test power at all fuses once again done it a few times since ive had the car took a wire brush to the fuse terminals.

[GeorgeT]

Never mind.

[spider2081]

Not sure about a 79, but on an 80 the alternator light power is not fused. The brown wire at the starter solenoid goes to a single connection below the alternator and then into the car. Behind the dash there is another 4 terminal block that the brown wire passes through. From there it connects to the connector for the ignition switch When the switch is in the "run or start" position power leaves the switch passes through the ignition switch connector and continues to the hot side of fuse 2 and continues to the alternator charge/warning light.
This is the brown wire that gets so much attention as problematic in Fiats. Any of the connections I mentioned could be contributing to your problem.

Hope this helps

[santafe308]

well i tested power going to alt. and b+ has positive voltage so i assume that the alt or regulator is bad so now to get a new one when money is available.

[santafe308]

well i special ordered the alternator at napa auto parts .ended up the old alt. was the 55 amp bocsh so now the new alt will be the 65 amp. should be here in the next few days ended up costing in total $82 not bad i guess.

[santafe308]

so got the new alternator in today took a matter of mins now light comes on like it should then goes off after motor is on so it was a simple fix just needed a replacement now to do the tune up and install the mechanical oil gauge also got the 14mm adapter kit to install it today.