Date: Sat, 23 Sep 2006 11:13:09 PST From: mojavegnospamveg.lsan.mdsg-pacwest.com (Everett M. Greene) Subject: Re: Saab 900 classic brake light switch
"James Rosenkranz" <fireglownospamsouth.net> writes: > My son has a '89 Saab 900. Early this year I replaced the brake light > switch. The faulty switch was sometimes sticking ON causing the battery to > run down when parked. The replacement was a new switch from eeuroparts.com. > > Now months later, my son reported that the brake light was permanently on > while parked and he had to pull the 15A fuse to extinguish the brake lights. > > While trouble shooting this, I found the brake light switch to be quite warm > to the touch while in the rest position. I checked it with an ohm meter and > found 0 ohms when closed, and 100 ohms when supposedly open. With the switch > removed from the circuit, I found I could correctly activate the brake > lights with a jumper. An ammeter shows the brake circuit drew 7-8 amps when > activated. This seemed reasonable since the circuit is fused for 15. > > So it appears that this relatively new brake light switch is faulty and is > acting as a resistor rather than a switch. So I'm inclined to replace it > with another new one. But I have this nagging feeling that perhaps there may > be something wrong that caused the failure of the switch. > > So am I overly concerned? Should I just replace the switch with another new > one and not worry about it? Or is there some other possibility that I need > to consider? If this were a Ford product, I'd be concerned about another "better idea" that's gone astray. It seems quite unlikely that two switches would both fail in short order unless there's something external causing a problem. On the other hand, switches don't casually fail -- they either keep working or fail catastrophically (smoke, flames, molten metal, flying pieces,...). The 100 ohm "open" reading is quite puzzling. It seems as if something inside the switch housing has melted and is bridging the circuitry, but it's hard to guess what has happened without opening the switch package. And it's hard to imagine what there is within a mechanical switch that can melt... I'd be inclined to get another switch and advise the seller that the new switch is a replacement for an earlier one that failed shortly after purchase. This wouldn't be a warranty claim but it would create a record of the incident in case another fails in a similar fashion. Reporting the failure might get a response from the seller of a known defect either in the switches or an external cause of the failures.
