Silly headlamp problem on '93 9000

Hi all,
I have had various headlight problems since purchase of my 'lemon' 9000 CSE 2.0 LPT.
I fixed most of them by replacing / fixing the 'headlamp control unit'
that detects bust filaments.
For your info - said unit ( the orange one ) packs up due to vibration causing solder joints to fail. Wish I'd known that earlier ! Anyway I found a replacement ( also turned out to be defective long term but I was on the case by then and fixed both the original and replacement with a soldering iron ! ).
Since then it's been better but occasionally one headlamp won't illuminate on dip beam ( normally the offside one - UK - but very occassionally the nearside one ). Full beam never seems to be a problem. When the bulb doesn't illuminate, the dash displays a fault so the 'control unit' is doing its job.
A 'thump' to the headlamp glass normally fixes it - as does driving some distance - you normally hit a bump that encourages the unilluminated bulb to spring to life.
Is there a known weak spot that accounts for this ? I'm really puzzled.
Graham
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Are you sure the bulb is not blown? Sometimes the broken filamnet will remain attached to the poles and swing around in the bulb envelope until the two ends touch together, temporarily welding itself, only to beak apart at the next cooling cycle.
-Fred W
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The Malt Hound wrote:

I'm familar with the failure mode you mention. In fact I once had a bedside lamp that failed that way and I used to swing it around to re-make the contact just for fun !
The last time they played up it was the n/s lamp that was out. I guess both filaments could be bust ? I've got some high intensity Xenon ? replacements anyway so I guess I should simply swap them out. Never seen this with car lights before though.
Ohhh - something that might provide another clue. When I first noticed the problem, adjusting the beam height control would sometimes fix it.
Graham
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In that case it does sound like its either back to the light control module or the stalk switch.
-Fred W
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Pooh Bear wrote:

Uhh. No Saab is a lemon, but may lack maintenance. The 93 9000 CSE 2.0 LPT is one of the best.

If this is the case, then it must be a weak connection to the bulb. Try to trace the wiring and improve the grip of terminals/connectors. Make sure that the small spring is correctly hooked into the bulb to keep it in place.

Access to the headlamp is fiddly. I've recently had a problem where both headlamps appears faulty on the dash display. Then I just turn the headlamp switch off and on again, and the problem goes away. Maybe this is due to dampness this time of year in this damp country, like when my old PC sometimes starts up with the default 480x640 screen resolution; I immediately restart and it's OK.
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Johannes H Andersen wrote:

Definite lack of maintenance I'd say. For me it was simply a 'lemon' purchase. Long story. It was advertised as lowish mileage for a '93 (110,000 mi ) with almost full Saab dealer service history. Turns out that the dash had been changed @ around 45,000 mi and the delaer hadn't spotted the odd mileage glitch in the log !
I got my money back ( ebay purchase btw ) and kept the car ( it was that bad the dealer didn't want it back ) but even at that price I'm not convinced it was a good deal.

That's what it seems like to me.
Guess I'll just need to probe further.

Faulty headlamp warning ( if the lamp is actually on ) is definitely the 'lamp control unit' - the orange relay looking like thing in the relay box under the hood /bonnet. It's most likely the case if the lamp's intermittent too.
It just contains some electronics to monitor the bulb current.
If you know how to use a soldering iron and a model knife ( to remove one of the 3 cover retaining tabs on the orange body ) it's easily fixed by resoldering the connections to the printed circuit board. These connections fail due to the engine bay environment.
Graham
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On Thu, 03 Feb 2005 00:34:44 +0000, Pooh Bear

Having a similar problem on my daughter's '94 900s(NG). I have found the problem is the high beam wire between the connector at the back of the housing and the plug at the back of the lamp. I just have to figure a way to remove the harness connector in the housing. There is not very much room between the reflector and the outside of the housing. _________________________________________ Usenet Zone Free Binaries Usenet Server More than 120,000 groups Unlimited download http://www.usenetzone.com to open account
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