2000 Stratus Crankshaft Position Sensor Question

[twistednerve]

Car was running fine for 1 hour it broke down. *It made a little bit of an unusual noise when I first started it, but it was also 15 degrees outside so I didn't think too much of it. *Car seemed to have no problem running & all gauges and indicators looked fine. *Turned off the car and went inside. *About 3 hrs later the car wouldn't start. *The engine turns over fine, but it never seems to fire. *I put a timing light between the coil of #1 sparkplug & the sparkplug wire and didn't see any fire occurring. *

I have a Haynes manual which told of a few things to check with a
digital voltmeter. *1st was the cam position sensor, 2nd was the crankshaft position sensor, and finally the ASD (Automatic shutdown) relay. *

The cam position sensor seemed perfect. *

The crankshaft position sensor seemed a bit off in that according to the haynes manual the sensor itself should be putting out voltages between 0.3V & 5 V when the engine is turning, I'm only reading between 0V & ~2.5V when the engine is turning. *This does concern me a little. The supply voltage going to the sensor looked fine. (8.8V)

Finally the ASD relay itself seemed good, but the on the PDC to the relay seemed odd. *The common feed (#30) looked good, but the Coil Battery socket on the PDC (#86) which should only have voltage on it when the key is ON according to the manual, had 12V all the time, even if the key was turned off and removed altogether. *

To me the last two seem strange, but I've heard the these Haynes manuals are prone to have errors in them, so I didn't know if any of these seemed to be obvious problems or not. *

Any help would be tremendously appreciated.

Thanks,

-Tim

[Dodgevanman]

It's most likely the crank sensor...the ASD relay, to the best of my knowledge is involved with fuel delivery and injector function and is not related to the ignition. The crank sensor sends the signal for ignition timing and the cam sensor sends the signal for injector timing.

[rkfsm]

All the things I can think of regarding a crank and no start:

Out of Gas
Battery low (Not enough volts to fire plugs)
Loose or corroded battery terminals
Leaking fuel injector(s)
Faulty fuel pump
Broken, stripped or damaged timing chain/belt
Worn or incorrectly gapped spark plugs
broken, loose or disconnected wiring in the start circuit
Faulty coil(s)
broken, loose or disconnected primary or secondary ignition wiring
Defective Crankshaft sensor, camshaft sensor or PCM


You do have gas, right? Obvious, yes, but sometimes it's missed.

I see you get 8.8v "supply" to the CKP. Well, a battery should not drop below 9.6v while starting. Check #3 above too.

The ASD relay provides power to the alternator field, injectors, coil(s) and heating elements of the O2 sensors. The PCM is programmed to disconnect the ASD if it does not get readings from the CMP and CKP. According to the schematics I have, the ASD is connected to the "Always Hot" bus via a 20, 25 or 30 Amp fuse (depending on year/make/model/body style/engine). The PCM supplies a ground to activate the ASD relay, so check both sides of the ASD winding. If both sides are hot, the ASD isn't closing because there is no current flow through the electro-magnetic winding. You should try and make sure that the signal you're getting at the sensor is getting to the PCM. You could have a broken wire along the way. Another easy way to tell if the ASD is activating is to meter the winding terminal on the alternator and have someone crank. If it goes hot, then the CKP, CMP and ASD are all good.

Also a digital meter is not going to respond very well to a variable signal (like from the CKP). Most DMM's only refresh their display once a second. If your DMM has a peak hold function, then use that. If not, go buy the el Cheapo analog meter from Radio Shack for $12. Those little suckers are incredibly accurate and often times leave more expensive digitals in the dust.

BTW, I wouldn't use a timing light to check for spark. Especially on a D.I. system. Pull a spark plug boot, put the male end of a 3/8" drive extension into the boot and lay the extension in such a way that there is a small gap to ground.

Hope this helps.

RK