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melle
V4 Guru

United Kingdom
2836 Posts

Posted - 30 Apr 2019 :  22:23:26 Show Profile Visit melle's Homepage Reply with Quote
The high beam pilot light in my 96 is hardly visible when on (early type speedo), so I wanted to replace the bulb with a much brighter T5 LED. However, I can't get the LED to work as it should. It comes on when I switch from main to high beam and back to main, but it doesn't stay on. The wire has 12V when high beam is on and the speedo is earthed properly, as all other lights work. What's going on here?!

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OWEN
V4 Fanatic

United Kingdom
285 Posts

Posted - 01 May 2019 :  21:47:16 Show Profile Reply with Quote
This is certainly weird; too weird to reply to, but............. If it was me, I'd disconnect the alternator so that the bulb's just working off the 12V DC battery without any possibility of a frequency issue; can't even remember if LED's are sensitive to frequency but that's what I'd try.
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melle
V4 Guru

United Kingdom
2836 Posts

Posted - 01 May 2019 :  22:05:04 Show Profile Visit melle's Homepage Reply with Quote
Shouldn't be an issue, the speedo illumination also is an LED and that works fine. I've also fed the LED directly from the battery and that also worked. My C900, which has a similar headlamp relay iirc, has an LED high beam pilot light (in fact, all lights but the alternator light in the 900's dash are LEDS).

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OWEN
V4 Fanatic

United Kingdom
285 Posts

Posted - 04 May 2019 :  09:39:32 Show Profile Reply with Quote
Indeed Melle, it shouldn't be an issue but given that there is an issue I guess I'd be disconnecting the alternator as an experiment and then switching LED's around to see if that was the issue.
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melle
V4 Guru

United Kingdom
2836 Posts

Posted - 04 May 2019 :  22:04:21 Show Profile Visit melle's Homepage Reply with Quote
I've refitted the incandescent bulb for now...

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beta
V4 Fanatic

Ireland
278 Posts

Posted - 05 May 2019 :  00:47:19 Show Profile Reply with Quote
Hi Melle
Could it be a dodgy bulb? led bulbs have electronics built in. Try wiring that particular bulb to another 12v source?
Don't worry im saving a few jobs on my Saab 900 for you.
Paul
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melle
V4 Guru

United Kingdom
2836 Posts

Posted - 05 May 2019 :  19:01:58 Show Profile Visit melle's Homepage Reply with Quote
I've tried different bulbs, both in the clock and fed directly from the battery and from a 12V power adaptor. All worked fine, just not in the clock. Could the headlamp relay have anything to do with it? It's of course of the mechanical type, whereas the one in the 900 is a solid state relay I think.

quote:
Originally posted by beta
Don't worry im saving a few jobs on my Saab 900 for you.
Paul
Electrical jobs?

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Edited by - melle on 05 May 2019 19:03:32
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melle
V4 Guru

United Kingdom
2836 Posts

Posted - 26 Jun 2019 :  22:23:11 Show Profile Visit melle's Homepage Reply with Quote
I tried installing a C900 relay (thank you Wonky Door!) this morning, but this threw up a new issue. When I switch on the lights, they're on high beam. I can switch back to dipped beam no problem. When I switch the lights off and back on, they're on high beam again. What's going on here? I've put the old relay back for now...

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Derek
V4 Guru

United Kingdom
1873 Posts

Posted - 27 Jun 2019 :  10:11:02 Show Profile Reply with Quote
Logical but not necessarily correct thought might say the relay is wired the opposite way round to what it should be. One way would default to dip and the other to main when switched on. This assuming it is a flip-flop relay.
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melle
V4 Guru

United Kingdom
2836 Posts

Posted - 27 Jun 2019 :  17:46:07 Show Profile Visit melle's Homepage Reply with Quote
What is a flip-flop relay? As far as I understand the schematic on both relays, they're identical. Will check again.

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Wheelspin
V4 Beginner

Denmark
72 Posts

Posted - 28 Jun 2019 :  08:44:40 Show Profile Reply with Quote
As far as I know the solid state og900 light relays are wired differently that the mechanical ones for og900, so they're not a direct swap. They changed around MY89...
The advantage of the solid state relay should be that it always starts in dipped regardless of it's position when you earlier powered of the car, so it does sound like it's just some wires not matching up.
/Mads
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melle
V4 Guru

United Kingdom
2836 Posts

Posted - 28 Jun 2019 :  08:53:30 Show Profile Visit melle's Homepage Reply with Quote
I'll study the diagrams a bit better when I have time! My '88 900 has a solid state relay, the same type I was trying to install in the 96.




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Edited by - melle on 28 Jun 2019 08:54:02
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Derek
V4 Guru

United Kingdom
1873 Posts

Posted - 28 Jun 2019 :  23:02:59 Show Profile Reply with Quote
A flip-flop relay works with a dip switch lever that is sprung loaded to a set position. You pull it back to send a signal to the relay and it changes the internal switch by flipping a lever to one contact and back again when you pull the lever again. Pull for main or pull for dip.
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melle
V4 Guru

United Kingdom
2836 Posts

Posted - 28 Jun 2019 :  23:09:54 Show Profile Visit melle's Homepage Reply with Quote
The C900 one is a solid state relay, so there won't be any mechanical parts as far as I understand it, but its functioning may be equivalent to the electro mechanical V4 relay?

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melle
V4 Guru

United Kingdom
2836 Posts

Posted - 06 Jul 2019 :  13:08:47 Show Profile Visit melle's Homepage Reply with Quote
Recap: I've transposed all wires from the original mechanical relay to the equivalent terminals on the new relay and I've assumed that position "F" on the mechanical relay is "56b" on the solid state one. The new relay itself works fine, but when switching on the lights it goes to high beam as default. I've been studying the diagrams again, but I can't figure out what wires I should swap to get it to switch on dipped beam when the lights are switched on.

If anyone could advise how the new relay should be wired up, that would be awesome.




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greg124
V4 Fan

United Kingdom
169 Posts

Posted - 07 Jul 2019 :  00:06:55 Show Profile Reply with Quote
With the new relay have you got main beam connected to 56a and dip connected to 56b? (or vice versa)
Does the main beam tell-tale on the dash now come on with main or dipped beam?
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