I have a student in a heavy equipment class that has a 2001 Neon that has no spark from coil to #1 and 4 cylinder, also will not light check engine light or produce codes. Coil pack has 3 wires, One is power the other two must be the signal ground to computer, not getting signal pulse on one groundwire. Does computer control coil or a seperate module pulse coil?Doubt it would be Crank sensor, fires on #2 and3.Local Dodge dealermuchless than helpful for unfortunate student. Will not supply theory of operation of ignition system or wiring diagram. Can anyone supply either, or some insight?

Thank you

 

Will a scanner communicate with the computer? I believe fuse 11 in the fuse box is the voltage circuit for the cel and a couple of the other gages. It might just be the lite.

With the vehicle cranking, the computer has to see a cam and crank signal or it won't ground the ASD relay. That relay controls voltage for the coil pack--- injectors --- among others things. That's my understanding.

The computer controls the ground circuits for the coils.

 

As an update; After checking ignition circuit from the coil pack back to the computer it was determined by the students that there is no pulsed grounding of the coil circuit for #1 and 4. Checking continuity on the ground pulse wire Black w/ white tracer shows continuity to computer from the coil. Unless there is a some faulty information ( defective sensor)that the computer is receiving, it would have to be assumed that the computer is defective. Fuses are good,power to computer is good. Now, the question is, is computer the cause or just part of a larger symptom. All your assistance is appreciated.

Thank you

 

tap on it with a rubber mallet and if u get a signal the computer has a short lol

 

its a bad coil probably

 

Did they do a resistance test on the coil pack? The primary circuits- .45--.65 ohms. The secondary circuits 5K--- 14K ohms. These are just generic specs. With the engine cranking, does the circuit in question have voltage?

If you can't communicate with the computer using a scanner, there seems to be more than one problem.

 

Students have checked resistance for both primary and secondary and check as stated. Can fire coil #1 and 4 by backprobing and intermittently grounding b/w coil signal wire to computerwith ASD relay enabled. Problem must exist in computer, with wiring connected only firing on #2 and 3. Are computers in Neons a frequent issue?

Thank you

 

I have a 97 neon and I have had the same problem you are describing for about two years, lol. I too assumed the PCM was bad, but that was replaced with two different computers and still nothing. Also did the wiring harness, crank sensor, cam sensor, coil pack, reset timing, etc. If you do figure out the problem, can you be sure to let us know?

 

I doubt the sensors are bad, if you were getting no spark on both sides of the coil pack then I'd look at the sensors. I would cut and swap the gound wires to the coil pack. If the problem stays in the 1 & 4 cylinder, it's the coil. If the problem jumps to the 2 & 3 cylinder, I'd look at the PCM and the wiring between it and thesplice (including the PCM plugs.)

 

Further update; used an analog ohmeter between the crank sensor wires while cranking engine and had plenty of needle movement. Crank and crank signal input into computer was verified as good. Used a 12 volt test light between 12 volt supply to ignition coil and and the trigger wires individually back to the computer. # 2 and #3 cylinder trigger wire pulse while #1 and #4 wire will not pulse while cranking. By process of elimination everything functions as required but the computer. Replaced computerwith known good part, coil fires on all cylinders, A+.Neon roadworthy again, A+. Student very happy, A+. LocalChrysler assistance in supplying wiring diagram or theory of operation,to students working in a lab doing diagnostic work, D-.

Thank you for your help.