Chrysler Repair: no start problem, sebring conv, crankshaft sensor

Question
I recently bought a 1996 chrysler sebring conv. with a 2.4 liter engine. Ran fine for awhile and then the car would not start. Had it put on a dignostic machine and the read out said the cam shaft sensor was bad. Replaced it. Car will run for awhile and then will not start for a few days(is not getting a spark from coilpack). Replaced ignition switch and coil pack as well as wires and spark plugs. The last time this happened I took it to a garage to have it looked at. Car would not start when they took it inside but after a few trys it started. Dignostic was run on it for no-start. Printout said it was fine. Took the car to a few mechanics and they dont know whats wrong. It is a good running car when it wants to run and would like to fix it but cant drive it nowhere because it may not start. Any info you could give me would be greatly appreciated. Thank, Jim

Answer
Hi James,
When it fails to start you can often get to the bottom of the cause, or at least localize it, by doing a simple test or observation at that time. First would be to have a spare spark plug so that you can then pull off one of the spark plug connector caps (twist and pull on the connector proper not the wire) and insert the spare plug. Then find a helper to crank the engine while you hold the threaded end of the spark plug against the cylinder head (holding it by the disconnected spark plug cap) and observe for a spark to jump the gap or not or just for 1-2 seconds of a full 5 second crank. If you don't get any spark then I would suspect the spark coil or autoshutdown relay. If you get spark for 1-2 seconds I would suspect the crankshaft sensor, if you get full 5 seconds of spark, then the spark circuit is o.k.
Then you can listen for the sound of the fuel pump which will run for 1-2 seconds when you turn the ignition switch from off to run position. If not, then the fuel pump could be flakey, or the autoshutdown relay is flakey. A voltage measurement of the output of the relay to the fuel pump would tell you which.
The most useful thing to do to be prepared would be to readout the controller for fault codes now, which you can do yourself, at anytime. Here is how:
Reading out the engine controller memory for fault codes is the first step. Try using the ignition key: turn it "on-off-on-off-on" and leave it "on" (doing this quickly, no longer than 5 seconds). By "on" I mean just the normal position when the engine is running, not the cranking position. The 'check engine'light will remain on when you leave the key in the "on" position with the engine still not running. But then watch the 'check engine' light to begin flashing, then pause, flashing, pause, etc. Count the number of flashes before each pause and keep track of the numbers. Repeat the readout and verify the counts are correct. Then group them in pairs in the order that they came out, thus forming two digit numbers. You may notice that the pause is shorter between the digits of a given number, and longer between the numbers themselves. Then send me a 'follow-up' question telling me the results of your readout. By the way, 55 will be the last number (two groups of 5 flashes each) and that is the code for "end of readout".
I have the troubleshooting manual for the 2.4L engines and we can look up the possibilities of what is wrong based upon what fault codes you show. There is also an essay on fault codes at the site:
http://www.allpar.com/fix/codes.html
which gives the meaning of the code numbers. But then you need to get specific info for what exactly might be the diagnostic tests or parts to replace to complete the repair. Let me know the codes and I can give you some direction. If there are no fault codes then the problem could be a spark issue or a fuel pump issue.
Old codes will self-erase in 50-100 key cycles, or you can erase them yourself by disconnecting the battery for a few minutes, but be aware that techique will set a new code 12 (battery disconnected recently) so don't get confused. But that is the way to wipe the slate clean of old codes.
I hope that with the above preparation and knowledge you can figure out why it won't start. Let me know what happens when it does.
Roland