A fast way to tell if you're on the right track is to connect a test light or voltmeter to either of the small terminals, (plugged-in wires or two small nuts) on the back of the alternator. You can also use the dark green wire with orange stripe, I believe, to the ignition coils or injectors. All of those points will have 12 volts for just one second after turning on the ignition switch. That's when you might hear the fuel pump run for that one second. What's important is that voltage should return as soon as you crank the engine. The voltage is supplied through the automatic shutdown (ASD) relay which is turned on by the Engine Computer when it sees engine rotation, (cranking or running). The computer knows the engine is rotating by the pulses it receives from the camshaft position sensor and crankshaft position sensor. The crank sensor doesn't cause much trouble. The cam sensor has caused a lot of trouble. The replacement might have a different plug than your old one. Redesigned sensors normally come with a new plug that must be spliced into the circuit.
If you find the ASD relay is not turning on during engine cranking, the stored diagnostic fault code will tell you which sensor is not sending pulses.
Also be aware that this is an "interference" engine. That means serious engine damage will result if the timing belt breaks or jumps a few teeth. To reduce the chance of that happening, the Engine Computer watches the relationship of the pulses from the two sensors to determine if the belt has jumped. If it jumps one tooth, the computer will turn on the Check Engine light and set a fault code related to "cam and crank sync". If the belt jumps two teeth, the computer will shut the engine down to protect it. You would have noticed poor performance. At three teeth, pistons will hit the valves and bend them.
Sunday, November 21st, 2010 AT 9:25 PM