Site News - 7/2/26: All Bulletin Board Ads Removed for Members | 6/26: Updated AI Bot Software and more news...
[General | Members | C900 | 9000 | NG900 & OG93 | 93 | 95 | NG95 | 99 | Sonett | Vintage Models | Clubs | Other Cars | FAQs | Gifts | Member Photo Galleries | Member Directory | Classifieds | Manuals | *Buddy Registry | *Mileage Registry | Polls | What's New | Raffle | Photo of the Month | Sponsors]

C900 Bulletin Board
1979-1993 & 94 Conv [Subscribe to Daily Digest]
(Search Author's Posts: e.g. Keyword:username)*Members Only

[Main C900 Bulletin Board | BBFAQ | Prev by Date | Next by Date | Post Followup ] Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
I don't remember wires' colors (+)
Like This Post: - Subscribe to Daily Digest for this Bulletin Board
Posted by Siegfried (more from Siegfried) on Wed, 12 Dec 2007 12:56:24 Share Post by Email
In Reply to: Re: charging.... or not, raabert, Wed, 12 Dec 2007 12:24:13
Alert me when someone posts in this thread:
Members see ZERO ads on the bulletin boards and get more feature. - Help Keep This Site Online - Signup

Alt can have from two up to four wires:
- thick one for load
- thin one for charging indicator light
- another thin one for voltage regulator (optional; most of alts use internal wiring to power up vr)
- the 3rd thin one for tachometer (optional as well; used mostly on old diesel engines)

If I'm not mistaken C900 uses two-wire setup (if noone else gives better answer I'll get back to you tonight with a shot of Bentley's page on this). The indicator lamp has one contact always assigned to '+' via ignition switch. Another contact runs to alt's rotor wiring. If the rotor is stopped it grounds this wire (although there's a resistance in the circuit but it doesn't play much here). If the rotor is spinning AND powered (via this very indicator) it makes ... longish. Long story short it starts supplying this indicator lump with '+'.
So:
- if rotor is stopped the lamp has '+' and '-' on both its ends. If the lamp is live it has nothing else but to light up.
- if rotor is powered and spinning the lamp has '+' on both its ends. There's no VOLTAGE (i.e. difference of potentials) across lamp's contact so the lamp is off.

So if your light is always off and you did smth with alternator then I'd suggest smth is with either with new alt or the wire that runs from the alternator to the indicator.

Zig

posted by 195.146.67...

Posts in this Thread:
Alert me when someone posts in this thread:
Members see ZERO ads on the bulletin boards and get more feature. - Help Keep This Site Online - Signup
Post a Followup

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.

Name: Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
E-Mail: (Optional)
Re-Enter E-Mail: (Confidential & Secure - Not revealed to other users!)
Note: Please check your spam folder for BB responses.

Subject:

Posting rules are simple - No for sale/wanted ads may be posted here - use the site classifieds.
You may not cross-post your message to multiple BBs.
Not permitted: political/religious topics and being disrespectful (personal attacks, insults, etc...).
 Site Members do not see any red text, inline ad links, bottom of page anchor ads, box ads, or anti-spam check.

Message: (please no for sale/wanted classifieds - post those in the Saabnet.com Classifieds)
Links are now automatically made active, no need for any special code (or use the Option Link field below) - don't put links in () or end with a '.'
To add inline images to your post, use [img]http://www.domain.com/img.jpg[endimg] (or use the Optional Image Link field below).

Links are now automatically made active, no need for any special code (or use the Option Link field below) - don't put links in () or end with a '.'
To add inline images to your post above, use [img]http://www.domain.com/img.jpg[endimg] (or use the Optional Image Link field below).
Optional Link: (e.g. http://www.saabnet.com/)
Link Title: (Optional)
Optional Photo/Image Link: (e.g. http://www.saabnet.com/img.jpg)
Photo/Image to Upload: (Please be patient while file uploads)



StateOfNine.com
SaabClub.com
Jak Stoll Performance
M Car Covers
Ad Available

The content on this site may not be republished without permission. Copyright © 1988-2026 - The Saab Network - saabnet.com.
For usage guidelines, see the Mission & Privacy Notice.
[Contact | Site Map | Saabnet.com on Facebook | Saabnet.com on Twitter | Shop Amazon via TSN | Site Donations]
Random Saabnet.com Member Gallery Photos (Click Image)

This is a moderated bulletin board - Posting is a privilege, not a right. Unsolicited commercial postings are not allowed (no spam). Please, no For Sale or Wanted postings, SERIOUSLY. Classifieds are to be listed in The Saab Network Classifieds pages. This is a problem solving forum for over 250,000 Saab owners, so expect to see problems discussed here even though our cars are generally very reliable. This is not an anything goes type of forum. Saabnet.com has been a moderated forum since 1988. For usage guidelines, see the Saabnet.com Mission and Purpose Page. Please remember that you are not anonymous. Site Contact | Site Donations | Other Sites by SP - Poverty2Prosperity.org | Run Club Menlo Park | ScreenBot
Site Members do not see red text instructions, bottom of the page anchor ads, or box ads.
Click here to see all the Site Membership Benefits!