9000 courtesy light

1995 9000 Aero. The drivers door courtesy light (the light in the door itself) has stopped working when the door opens. The passengers side is ok. When I press the switch on the hinge side door sill I hear a "click" coming from behind the fusebox console under the dash, suggesting that someting is working (a relay switch?). The globe and fuse are ok and if I earth out the black wire on the light the lamp comes on, the other wire to the light is permanently live. The switch on the door sill has two wires. One is live, the other not. I can't work out how this works!! (It's obviously not simply a switch that creates a circuit and lights the lamp) Anybody help me out here with how the system works or what is likely to be wrong?

Pete

Reply to
pmg
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I've got the same problem -- 1995 9000CS. The light works fine when I turn it on, but doesn't come on when the door is opened.

Let me know if you figure out a fix. snipped-for-privacy@madmousergraphics.com

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Reply to
LauraK

LOL Why couldn't Saab have simply created a simple loop with an earthing switch..........life wasn't meant to be easy eh?

Pete

Reply to
pmg

A schematic diagram makes it clear how the lights, relays and switches = are wired.=20

Assuming both wires are still attached to the switch; the other wire = should also become 'live' when the door is open. From your description I would think that the door switch activates a = relay and the relay connects the lamp to ground. Since the lamp works = when you wire it to ground with a loose wire, I think that the fault is = in the relay or between the relay and a ground contact.

------------------------------------------- MH '72 97 '77 96 '78 95 '79 96

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Reply to
MH

Yes........good reasoning I'll investigate the realy. I can hear it "clicking". Perhaps just an earth problem.

Pete

A schematic diagram makes it clear how the lights, relays and switches are wired.

Assuming both wires are still attached to the switch; the other wire should also become 'live' when the door is open. From your description I would think that the door switch activates a relay and the relay connects the lamp to ground. Since the lamp works when you wire it to ground with a loose wire, I think that the fault is in the relay or between the relay and a ground contact.

------------------------------------------- MH '72 97 '77 96 '78 95 '79 96

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Reply to
pmg

This is definitely not the dome light that is giving you trouble. If this is so, then you have a bad relay which is "pulling-in" but not closing the circircuit. This is not an uncommon failure.

Have you determined which relay is"clicking" and if so have you tried shorting around it. If this works, replace the relay.

Malcolm

Reply to
Malcolm

No, not the dome light. I have a wiring diagram here and it shows the dome light as being connected to the switch via a time delay relay. But the diagram also shows the door courtesy light as being a simple circuit using the switch to earth the circuit. So this is just a little weird!!

Pete

Reply to
pmg

If the door light is controlled directly from the door switch, what is the "clicking you hear when you operate the swithch manually? Despite what the wiring diagram shows, it sounds like a rewlay pulling in but the circuit is not being closed.

It would not be the first time that a production change was made and the specs caught up later.

There is more to "Pragmatism" than William James explained.

the light is permanently live.

It sure sounds like the light is connected to ground (earth--This is a very bad bit of engineering--switching the ground(earth) side of any load) by a relay which is operated by the circuit completed by the door switch.

Malcolm

Reply to
Malcolm

the light is permanently live.

Actually, it is not so bad... If it grounds instead of completing the circuit, you can use this event to key other items such as an alarm... The relay you hear clicking is probably the one for the power seat. There are 2 things activated by the door switch. One allows the seat to be adjusted when the door is opened and the other grounds the dome light circuit to trigger it. When it looses a ground, it tells it to fade out unless the ignition is switched on, in which case it goes out immediately. Try pulling the switch in the car. I think there are 2 circuits on the switch, but am not sure. Try replacing the switch. These are not the most robust. I think they cost 15.00 or so at saabsite.com.

KeithG

Reply to
KeithG

This little bit of engineering seems to be standard in US made cars. Run a hot wire to the courtesy lamp, then the switch only needs one wire to it, since it's grounded to the door frame. Cheap switch, one less wire... what's the problem?

Harvey

Reply to
Harvey White

Then if the switch connects the 'live' wire to ground there would be a = short circuit and some fuse should blow... Does the switch connect the = two wires or does it connect them both to ground? (The ground contact of = the switch may not be easily visible).

The 'live' side of the switch is connected to the coil of the relay = (contact 85) The relay coil gets its power on contact 86, the light is = in a circuit with relay contacts 30/51 and 87 - yes?

How did you measure the 'live' side of the switch? With a voltmeter or a = check light? If you used a voltmeter, then what you are measuring on the door switch = may not really be 'live' but the 12 V on the 'hot' side of the relay, = through its coil.=20 Since the voltmeter has a very high internal resistance it does not draw = a high current through the relay coil so there is no voltage drop over = it and the meter shows 12 V. The current through the coil and the meter = is not enough to make the relay work. If you connect the 'live' switch = wire to ground the relay should click 'on'.

What happens If you use a test light between the 'live' door contact and = ground? If the contact is really 'live', the test light should come on = bright.

------------------------------------------- MH '72 97 '77 96 '78 95 '79 96

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Reply to
MH

OK The wiring diagram shows the door switch to be two switches in one, each connecting their respective connectrions to earth (via the self tapping attaching screw) when the door opens. The first connection comes from the time delay relay (this is the click I hear) and operates the dome light when the door opens. The second is a simple (and totally separate) earthing switch with the connection running to the courtesy light in the door. The other side of this light is live and the switch simply completes the circuit. It seems the wire from the switch to the courtesy light has broken somewhere within the door cavity because if I earth the non-live side of the courtesy lamp it lights up, but not if I earth the equivalent wire at the door switch. The "click" is not related to the courtesy light at all.

Pete

Then if the switch connects the 'live' wire to ground there would be a short circuit and some fuse should blow... Does the switch connect the two wires or does it connect them both to ground? (The ground contact of the switch may not be easily visible).

The 'live' side of the switch is connected to the coil of the relay (contact

85) The relay coil gets its power on contact 86, the light is in a circuit with relay contacts 30/51 and 87 - yes?

How did you measure the 'live' side of the switch? With a voltmeter or a check light? If you used a voltmeter, then what you are measuring on the door switch may not really be 'live' but the 12 V on the 'hot' side of the relay, through its coil. Since the voltmeter has a very high internal resistance it does not draw a high current through the relay coil so there is no voltage drop over it and the meter shows 12 V. The current through the coil and the meter is not enough to make the relay work. If you connect the 'live' switch wire to ground the relay should click 'on'.

What happens If you use a test light between the 'live' door contact and ground? If the contact is really 'live', the test light should come on bright.

------------------------------------------- MH '72 97 '77 96 '78 95 '79 96

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Reply to
pmg

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