Saab Alternator ground

SwedishWrench,

    I have a 89 Saab 900. The alternator is putting out about 11.7 when the car is running.The battery is about the same voltage. I put another battery in the car and it was the same. I charged and checked the battery. Nothing wrong. I had the alternator removed and tested it tested and it put out 14 volts. The battery and alternator don't seem to have a problem. When the car is running it's draining the battery. I have not checked for parasitic drains yet. If there is no drains what else could be wrong. Please email me back

Hi,
      You will want to check the ground strap to the alternator this black wire is known to break. This is the black wire(s) bolted to the alternator case and back to the engine block. Your next test is for Field voltage this is the small wire on the back of the alternator (usually green) marked DF. You should test this wire with the ignition on and the wire unplugged from the alt. You should find around 9 volts or so, but the main thing is you find some voltage if you have no voltage here your alternator will never start to charge. If this is your problem you will have to trace this circuit back through the battery light on your dash for this you should see your wiring diagram. If you had a parasitic drain the battery would die when it is parked for a day or more. You have a charging problem see my article on charging system tests.
Good luck,

Jason

(This article is meant to educate a consumer,or as a guideline for professionals. You can cause serious damage to your vehicle and/or cause yourself injury. Only those qualified should attempt repairs. I do my best to assure that the above info is correct but take no responsibility for any damages incurred.)

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