Return-Path: Sender: (Marvin Kaye) To: flyrotary Date: Mon, 10 Feb 2003 22:04:22 -0500 Message-ID: X-Original-Return-Path: Received: from ms-smtp-03.southeast.rr.com ([24.93.67.84] verified) by logan.com (CommuniGate Pro SMTP 4.0.5) with ESMTP id 2014442 for flyrotary@lancaironline.net; Mon, 10 Feb 2003 11:58:50 -0500 Received: from mail4.carolina.rr.com (fe4 [24.93.67.51]) by ms-smtp-03.southeast.rr.com (8.12.5/8.12.2) with ESMTP id h1AGvqiC010813 for ; Mon, 10 Feb 2003 11:57:55 -0500 (EST) Received: from o7y6b5 ([24.25.70.165]) by mail4.carolina.rr.com with Microsoft SMTPSVC(5.5.1877.757.75); Mon, 10 Feb 2003 12:00:00 -0500 X-Original-Message-ID: <002201c2d126$bb3e9b40$1702a8c0@WorkGroup> From: "Ed Anderson" X-Original-To: "flyrotary" Subject: Mazda Alternator Lamp circuit X-Original-Date: Mon, 10 Feb 2003 12:06:19 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 I've been working with Tommy James on his alternator problem and the question came up (it always comes up) - do we need the diode and relay shown on the Mazda alternator wiring diagrams. It appears that if you are using the Mazda alternator (mine is Bosch rebuild) then you do indeed need the diode (and the relay if you want an lamp indicator) in the circuit going to the "L" (Lamp?) terminal of the alternator. You certainly need the "L" circuit to provide voltage to the alternator for the following reason. With the engine off, a current from the battery flows in the "L" circuit closing the relay and thereby turning on the lamp (to indicate no charging when the alternator is not running), and then throught the diode to the alternators field coil (internally). This current provides the "initial" starting current for the field coil of the alternator. Once the alternator starts producing its own voltage then the regulator switches to using the alternator's internally generated voltage for regulation. The "L" wire then has essentially equal voltage on both sides of the diode which turns it "off" stopping the current flow through it and the relay causing the "lamp" to go out. For this reason, it is probably not wise to put a lamp directly in the "L" circuit of the alternator (if it is one of the type described) because should the lamp burn out or otherwise cause an open circuit, the alternator field coil will apparently not get the initial starting current and will fail to generate voltage. Thanks to Tommy James for causing me to research this a bit more as I had always wondered whether the "L" cirucit was needed if you didn't use the "lamp" feature. It turns out it is on this alternator! . . Ed Anderson Matthews, NC RV-6A N494BW eanderson@carolina.rr.com