Chrysler Repair: 1988 chrysler new yorker 3 liter quit running, chrysler new yorker, sensor unit

Question
Hello Rolland,my car cranks over but wont start. I have no fire to the fuel pump or coil.Could this be a computer or something else? This is our only transportation and I just cant figure this one out.Thank you so much,Howard  

Answer
Hi Carl,
This sounds "classic". The reason there is no power to the coil or the fuel pump is that the autoshutdown relay is not providing the power. The purpose of this system is to protect against fire in the case of an accident in which the engine stops with the igniton on, and having fuel and spark available might produce a fire.
The causes of shutdown without an accident are:
the photo-optic sensor in the distributor is not working
(that signal is required to be received at the computer for the autoshutdown relay to be closed),
the autoshutdown relay is defective,
the controller (computer) is defective,
or the wiring between them (or the wire from the battery to the autoshutdown relay) is compromised.
I would bet on the photo-optic sensor being the cause.
You can test that out by reading out the fault codes that are stored in the computer:
Turn the ignition key as follows: off-on-off-on-off-on and leave in the on position (where "on" is the normal run position, and do the switching process in less than 5 elapsed seconds). Then watch for the check engine light to begin to flash, pause, flash, pause, etc. Count the number of flashes before each pause and make a mental or written note. The last two groups of flashes will be 5 in each. Then pair up the numbers of flashes in the order they came out in order to form two digit numbers, e.g. the last number so formed will be 55 (which is the code for "readout is completed"). If the first number is "11", (e.g. one flash, pause, one flash, pause,) that means the phot-optic sensor signal is not getting to the computer. Check the electrical disconnect plugs at the distributor and if they are o.k. then I would suggest you buy a new sensor unit.
If you don't have a manual that describes the several steps to disassemble the sensor unit from the distributor, let me know and I'll type it in and post it back to you.
If you don't get an 11 code, than we need to check for voltage coming into the shutdown relay, so let me know that as well. It sounds like you have a voltmeter and a timing light so this should be an easy repair. These unit's (and their 'sister' Hall effect sensors) don't last the life of the car.
Roland