Cadillac Repair: code po53, ac delco, resistance changes

Question
i have a 95 deville 4.9l that stalls for no reason and at all different speeds.had a code for map sensor short which i replaced. sometimes car will start right after stall but sometimes it has to sit a while. took it to local mechanic who said it had proper fuel pressure. he replaced the coil. drove the car approx 90 miles over afew trips and car stalled again. now have history code po53 for distributor signal interrupt. was wondering what this code means exactly. the stalling happens very intermittenly so it is a real inconvenience.hope you can help!!! thanks alot

Answer
Hi James,

     In simple terms it means that the ECM hasn't seen a signal from the ignition module for .4 seconds and that is enough time for the ECM to think you turned the key off so it stops pulseing the fuel injectors and the engine quits.

     According to the troubletree it could be an intermittant, shorted, open or wrong resistance pole piece inside the distributor. A bad wire or connection between the ECM and the distributor or a defective computor/ECM. Sometimes you can take the ECM down and with the engine running tap on the side of the box with your knuckles and due to a loose soldier joint the engine will stall.

    A likely suspect is the ignition module. It will test good but fail intermittantly when hot. If you don't find anything it might be worth replaceing but only with an AC Delco part because the others sometimes don't last as long.

   Another part that fails is the wireing harness inside the distributor. I take it out and place an ohmeter at each end of a wire a wiggle it or if it goes through a plastic block tap on it and see if the resistance changes. If it does replace both halfs because the plastic gets brittle and then you will not know where the wires go.

     This type of proble is tough to track down and some parts replacement might be needed before you get the right one. Hopefully you can test and find the culpret. Bill