Hi folks. Please allow me to make one comment that may head you in a different direction. That has to do with your understanding of the ASD relay. "Automatic shutdown", (ASD) relay is a confusing term due to how it works. This has nothing to do with the anti-theft system. Other manufacturers use a similar relay but with very different names. Its purpose is to stop the engine when one of two sensor signals goes missing.
Under normal operation, when you turn on the ignition switch, the Engine Computer turns the ASD relay on for roughly one second. During that one second, 12 volts is sent to the ignition coil(s), injectors, oxygen sensor heaters, and the fuel pump or fuel pump relay. If you can hear it over the chime, you may be able to hear the hum of the fuel pump for that one second. After that, the ASD relay is turned off until you crank the engine. At that time the crankshaft position sensor and the camshaft position sensor will develop signals that switch on and off multiple times per engine revolution. Those are the signals that tell the computer to turn the ASD relay back on. Now there's power to the ignition coils, injectors, and fuel pump.
That ASD relay remains on as long as the engine is rotating, (cranking or running). This is a safety circuit. If a fuel line is ruptured in a crash and the fuel pump were to remain running, raw fuel would get dumped onto the ground, creating a major fire hazard. Instead, with a broken fuel line, there can't be any fuel pressure. With no pressure, no fuel can spray from the injectors, so the engine stalls. Once stalled, there won't be any signals coming from the crankshaft position sensor or the camshaft position sensor. When either or both signals go missing, the computer turns the ASD off to stop the fuel pump.
A few manufacturers, Ford in particular, also used an "inertia switch" in their fuel pump circuit. Those tripped a circuit breaker if the vehicle sustained a hard enough impact. It's because of those that a lot of people incorrectly assume every vehicle has one.
Okay, I need to add a second comment of value. That has to do with the new battery. Even if everything else is working properly, the engine still may not start. By disconnecting the battery, the Engine Computer lost its memory. Most of the data will be quickly relearned without you even noticing, except for "minimum throttle". That takes a very specific set of conditions for the relearn to take place. Until that is done, the engine may not start unless you hold the accelerator pedal down 1/4". It will not provide the nice "idle flare-up" to 1500 rpm at start-up, and it will tend to stall at stop signs.
To meet the conditions for the relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the pedals.
At the mileage listed, a failed fuel pump is not uncommon either. Chrysler pumps almost always fail by failing to start up due to worn brushes in the motor. Banging on the bottom of the gas tank often gets them going.
Hope that helps. I'm anxious to see how this gets resolved.
Tuesday, January 31st, 2023 AT 10:59 PM
