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Re: Oil pressure sender, et al Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Thu, 14 Dec 2000 16:04:08
In Reply to: Re: Oil pressure sender, Andy [Profile/Gallery]
, Thu, 14 Dec 2000 15:16:29
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Methinks that you have what the Brits call 'A Royal Cock-Up'. I'm betting that your oil pressure gauge is mounted in the center console, most probably as part of a three-gauge package. That was an accessory gauge set for Saabs.
OK - One of those posts is for the pressure sender idiot light, the other for the gauge. I'll bet they are marked as such. You write that both wires to the sender are wrapped together, and that there are two posts. I'm a bit confused by that - both wires wrapped together and attached to both posts?!!?. One wire should be for the idiot light, the other the gauge, and no mixing!!!
Next - the alternator. There should be TWO connections on your alternator. One will be a big honking connection with at least one BIG red lead going off to the battery. There may be other wires, but this is Power Central for the positive lead. The other wire will be very thin, usually yellow but it doesn't have to be, that connects to a thin terminal on the voltage regulator. The regulator is a diamond-shaped device stuck on the back of the alternator. That thin wire goes to the battery light on the dashboard.
Quick theory - an alternator is a generator that uses electromagnets instead of permanent magnets (and some other differences I won't go into). When you turn the car ON, power flows through the battery, through the Battery light in the dash, through the thin wire on the back of the alternator, and that current goes into coils in the alternator. That current creats a magnetic field so the alternator can produce voltage. The light is ON when you turn the car to on because current is flowing through the bulb. Once the engine starts and the alternator is spinning, it starts producing its own voltage. It (actually, the voltage regulator) then starts supplying current to the (field) coils inside, and current stops flowing through that thin wire. With no current flow, the bulb goes out.
If that thin wire is broken, no current will flow into the alternator, and since the coils never have a magnetic field, the alternator doesn't produce voltage and charge the battery. Also, with that wire broken, the Battery light never comes on. However, if you somehow connected that thin wire to ground, the battery light would always be on. Heck, if you connected it to the oil pressure switch, the Battery light would tell you about your oil pressure.
I can't troubleshoot your wiring from your description. Get yourself a Bentley manual with good wiring diagrams and straighten it out.
good luck!
, Wed, 13 Dec 2000 19:43:31, Thu, 14 Dec 2000 06:36:29, Thu, 14 Dec 2000 09:15:07, Thu, 14 Dec 2000 14:21:58, Thu, 14 Dec 2000 14:48:11, Thu, 14 Dec 2000 15:16:29, Thu, 14 Dec 2000 16:04:08 <-- Viewing This Message
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