Sorry to leave you hanging. I actually had your last message on my 'puter yet, but with a bazillion windows open, I forgot to follow up.
I only have a '98 service manual, but the circuit should be the same. The cam and crank sensors are the only two that are needed for the engine computer to turn on the Automatic Shutdown (ASD) relay which powers up the fuel pump and ignition coil.
I wasn't thinking about your fuel pump comment. After overcoming my oldtimer's disease, if you indeed are hearing the fuel pump running during cranking, the ASD relay must be turning on. That would only leave the coil pack, however, before we condemn it, it would be smart to make a few tests. Use a voltmeter or test light to check for 12 volts on the dark green / orange stripe wire of the coil pack connector. That is the same circuit that feeds the fuel pump. Of course, you'll have to do this when it doesn't start. Remember, the voltage will only be there for about one second after turning on the ignition switch, then it will turn off. It should come back during cranking, so you'll either need a helper to crank the engine, or you'll have to set the meter or light so you can see it from inside the car.
If the voltage is there, and steady, during cranking, but there's still no spark on any plug wire, suspect an intermitent connection inside the coil pack. I would really expect that to cause an intermittent stall along with an intermittent failure to start. The grounds are made through two wires to the computer. The chances of both having an intermittent break at the same time isn't likely, so we won't look there for now.
If voltage is not there during cranking, watch for voltage on the dark green / orange wire when you first turn the ignition switch on. If you see voltage for one second, then it goes away, the wiring is good. If that happens, but it doesn't come back during cranking, that would contradict your hearing the fuel pump, so we won't pedal down that road now.
If the voltage is never there at the coil pack, try to dig down to the back of the alternator. There will be two small wires in a single plug. Perform the same voltage measurement on the dark green / orange wire in that plug. Actually, either wire will work but the dark green / no stripe can be expected to have less than 12 volts. You're after "something". Nothing is not acceptable. If you find voltage there during cranking, but not at the coil pack, there is a break in the dark green / orange wire between the coil pack and the splice for that wire. That isn't common, so I'll hold off following that line of thought for now. (Fingers are getting sore from typing).
If there's no voltage there either during cranking, bypass the ASD relay, then check for voltage at those places again. You can do this with the ignition switch turned off. An easy way to bypass a relay is to pop it out, snap the cover off, reinstall it without the cover, and gently squeeze the metal flipper with the contact. Sorry if I'm making it too simple. Some people have no idea what I'm referring to. You can also use a piece of wire or a paper clip. In the socket, with the relay removed, disregard the two parallel terminals on either side, and the unused center terminal. That leaves you with two terminals that form the letter "T". Those are the two to connect. When they're connected, there should be voltage to the coil, alternator, and you should hear the fuel pump run.
I'm going to quit for now because there's too many directions to go in. No sense retyping a service manual when the problem might be easy to find. One last comment though. During cranking, if you see pulsing in the test light or an erratic reading from the voltmeter, the ASD relay is pulsing on and off. There are further test procedures for that related to a shorted crankshaft position sensor or its wiring. It just occurred to me also that I took a Stratus to a Chrysler school once, and it cut out four times during the trip. The trainer mentioned a problem they were seeing where a wire for the camshaft position sensor woud lay against a sharp metal bracket, rub through, and ground out intermittently. If the 8 volt supply to the cam and crank sensors gets shorted to ground, the computer turns that supply off to protect it. The voltage will not come back until you turn the ignition switch off and back on.
When you encounter this no-start condition, what happens or what do you do to get it to start?
Monday, March 1st, 2010 AT 3:42 PM