Why is it that a 1999 Saab 9-5 with a charged battery won't start?

Answer 1

This is going to be either Expensive or Outrageous, if your problem is actually that it won't crank.

Your first task is to test the starter. Put your car in neutral, set the handbrake and chock the wheels before you do this! It looks like a big can mounted horizontally. There's a little horizontally mounted can right above it - like, a quarter inch above the big can. The little can has three wires coming out of it. One goes to the battery. One is real thin and goes off toward the passenger compartment, and the third goes into the big can. We'll call them the battery wire, the key wire and the starter wire. Get a hunk of 8-gauge wire and strip the ends, then short the battery and starter wires together. If the starter ran, short the battery and key wires. If the engine cranked, the starter's good. If it failed either test, you have the answer: unhook the battery, extract the starter from your car, take it and $108 plus tax to AutoZone, get a new one, put it in and be happy.

If the starter works, pull off the key wire and connect a voltmeter between it and ground. Turn the key to the start position and look for 12 volts, and if you see it keep reading. Here's an old VW driver trick: this wire picks up a ton of resistance from running past hot parts for years and years. What I want you to do, is to turn the key to the "run" position and try shorting the battery wire on the starter to the prong your key wire was on. The engine SHOULD start. If it does, you have two options. The first is kind of a pain: you gotta run a new wire. The lazy way that all the VW drivers use, is to buy a 30-amp foglight relay. It has four prongs: two for the coil, two for the switch. Hook the key wire to one of the coil prongs and ground the other. Connect the switch between the battery wire and the key wire prong on the starter. Then screw the relay to the side of the engine compartment. Relays take very little power to switch on, so this works great.

If you're getting no voltage you either have a broken wire, one that fell off, or you need a new ignition switch. This is also a $100 part.