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Saab: Alternator appears to be charging at below optimum..dash light…

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Saab charging issue. Alternator...
Saab charging issue. Alternator appears to be charging at below optimum. Exciter wire was broken and once repaired, the dash light burned out, now no electricity to exciter wire again. Alternator still really not charging properly. Even with jump from battery directly to alternator (exciter wire stud), the alternator appears to only be producing 12.8 volts or so.
Submitted: 8 years ago.Category: UK Car
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Answered in 1 hour by:
6/14/2010
UK Auto Mechanic: Matt, Mechanical Engineer replied 8 years ago
Matt
Matt, Mechanical Engineer
Category: UK Car
Satisfied Customers: 23,450
Experience: BEng hons Mech engineering, in auto industry 22 years
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hello

I'd check the resistance of the main positive lead that runs down to the alternator as anything more than a few ohms and it should be replaced, its also possible that there is an excessive current drain on the car and this is dragging down the alternator output.

I'd check the current drain aspect, the best way to find what circuit is causing the excessive currant drain is to fit a current sensing multimeter in series with the positive battery lead on the car and the battery.

A typical current drain with everything off and unalarmed should be around 0.05Amp and if its higher than this remove a fuse and re-measure, if measurement doesn't change then replace the fuse and remove the next.

Once you've isolated the circuit with the excessive drain check the wiring connections and plugs to components and the wiring harness that runs by the engine bay fuse box - the wiring harness chaffs / rubs through and gets damaged - but its not always easy to see so be careful when checking..

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