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T O P I C    R E V I E W
mellePosted - 30 Apr 2019 : 22:23:26
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?!
15   L A T E S T    R E P L I E S    (Newest First)
72sonett3Posted - 31 Jul 2019 : 16:35:53
I knew it would work as I have a red 900 relay in my '79 96 and it works fine.

Schematic of high beam, note that this circuit is not fused!
(#7 is the relay):

Schematic of low beam:

A flip-flop relay, a.k.a. bistable relay.

'72 97
'77 96L conv.
'79 96GL (LPG)
'83 900i (LPG)
'95 900SE conv.
'99 9-3T
mellePosted - 17 Jul 2019 : 20:08:53
72sonett3 came to the rescue today; wires from 56a and 56b exchanged and now the new relay works just fine. Next step is to crawl under the dash again to install the LED pilot light and see if the solid state relay fixes the original issue.
mellePosted - 07 Jul 2019 : 20:24:46
I've just swapped the wires over, I have no idea which wire is which, probably a good idea to study the wiring diagram. Haven't checked the tell tale, that may give a clue!
greg124Posted - 07 Jul 2019 : 00:06:55
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?
mellePosted - 06 Jul 2019 : 13:08:47
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.
mellePosted - 28 Jun 2019 : 23:09:54
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?
DerekPosted - 28 Jun 2019 : 23:02:59
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.
mellePosted - 28 Jun 2019 : 08:53:30
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.
WheelspinPosted - 28 Jun 2019 : 08:44:40
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.
mellePosted - 27 Jun 2019 : 17:46:07
What is a flip-flop relay? As far as I understand the schematic on both relays, they're identical. Will check again.
DerekPosted - 27 Jun 2019 : 10:11:02
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.
mellePosted - 26 Jun 2019 : 22:23:11
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...
mellePosted - 05 May 2019 : 19:01:58
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.

Originally posted by beta
Don't worry im saving a few jobs on my Saab 900 for you.
Electrical jobs?
betaPosted - 05 May 2019 : 00:47:19
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.
mellePosted - 04 May 2019 : 22:04:21
I've refitted the incandescent bulb for now...

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