1979-1993 & 94 Conv [Subscribe to Daily Digest] |
![]() | [Main C900 Bulletin Board | BBFAQ |
Prev by Date | Next by Date | Post Followup ]
Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
Re: Non-charging 87 900S (non-turbo) Posted by Ari [Email] ![]() ![]() In Reply to: Non-charging 87 900S (non-turbo), RonF, Wed, 23 Aug 2006 15:44:38 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Most alternator charging problems are the voltage regulator. The alternator itself can be thought of as some coils of wire and bearings. The coils rarely fail. About the only two things that cause charging failures in the alternator itself are worn commutators or a bad diode. The way to tell a worn commutator is to take out the VR and look. The only way to tell a bad diode is to use an oscilloscope.
You can only do so much testing with a voltmeter. You can read a bunch of things, but they don't add any information - just more data.
My recommendation is to replace the VR. It is painfully simple on a 900. If that fixes the problem, great. If not, it's is probably a worn commutator or bad diode. At that point, the easiest thing to do is put in a rebuilt alternator. When you give back the old alternator to get the core charge back, be sure to stick the old VR back in and keep the new VR you bought.
So buy the VR and try it. Better than 90% of the time that will fix it and you're done. If not and you need to replace the alternator, you'll get an alternator and a spare VR out of the deal. There are worse things.
posted by 192.249....
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
![]() |
![]() |
![]() |
![]() |
![]() |