Saab 9000 Hazard Lights - followup

Dealing with the older cars from across the pond, I tend to change the fuses out every two or three years. The cost is minimal and the main result is never having to be worried about the fuses.

I do not know that model, but are your light clusters individually fused, parallel from side to side or front to back?

Probably bad contacts in the fuse box and the signals were not getting enough power to the capacitor. When you turn on the hazard lights with the turn signal, you increased the potential (make appropriate noises of electricity being sucked) sufficiently to overcome the resistance in the corrosion. You get a similar problem with battery terminals that are corroded. When you hit the starter they work, but the alternator cannot push enough electrons to keep the battery charged.

JJ

Germ Scott wrote:

This doesn't make sense to me - fuses aren't a wear item, they don't degrade over time (unless incorectly specified for the circuit), and should only ever require replacement when they blow as a result of a circuit fault.

What is the logic behind replacing them?

The logic is that it's a lazy way of cleaning off any oxidation on the legs or the fuse holders.

Hmmm...

Even on cars with the fuse box under the bonnet (e.g. C900), this doesn't become a problem until the car is more than 20 years old or so. If the fuse box is internal (e.g. 9000), it's very unlikely to ever become a problem.

I've seen lots of oxidation problems in light fittings, but rarely in fuse boxes. Even the old bullet type fuses, which were truly dire IMHO, managed to maintain reasonable contact over long periods.

Therefore I would question the necessity of doing any fuse maintenance, except for maybe once every 10-15 years (pull out + push back in)

I have certainly had this problem with the window motor on my 9000. It is quite scary when you park the car in a murky underground car park and can't wind the windows up. However, fiddling with the appropriate fuse got the window going. There could have been the odd moisture inside the car from a wet floor mat.

I agree, that's what I meant by 'cleaning'.

Could it depend on temp/humidity/pollution where you drive. Once my 85

900GLE was 5yo it needed fuses and terminals removing & cleaning about annually or various things tended to get creative &/or not work. Mind you, blasting everything it with contact cleaner in situ would be quicker, cheaper and even lazier than replacement if you were so inclined.

Are the fuses ceramic, glass or plastic plug ins?

The ceramics have a tendency to have to conductor degrade as it is exposed to oxidation. The contact points need cleaning and an application of conductive grease.

Temperature extremes and vibration can cause the glass to separate from the ends and the cap rotate, twisting off the conductor where it is hidden by the cap.

The plastic flat fuses are least likely to need replacing and all the fuse wire is visible.

Local conditions will have an effect.

JJ