I have a 1996 3.3L T&C with over 405K miles. I am in a crank, no start situation. I think I have eliminated everything being the culprit except for the PCM.

Before plunging into the purchase of a PCM, I decided to do continuity checks on all the major player, Crankshaft Position Sensor, Camshaft Position Sensor and the Coil. I have found continuity between pin connectors where I don't think I should be getting continuity at all, but rather should be getting a 1. For example, the continuity between the PCM C1 40 (EGR) pin and the 4 pin on the ignition coil connect is 35.3 Other coil pins give the same type readings.

I'm a novice at this but I think I probably have some wires which have melted together. Are reading like that normal for totally unrelated components, i.e., coil and EGR pins?

Thanks for any guidance.

 

wire colors connector PIN location which ones are you checking ?

 

I am getting a crank with no start. Primarily I was checking wires 1 through 4 going to the ignition coil. Wires 1 through 4 going from bottom left to bottom right are 1 - 2 - 3 -4. Wire 3 is the power supply to the coil. Wires 1, 3 and 4 are the firing pulse to the coil.

My DVOM was apparently defective as I was getting ohm readings of 10 + on the pulse wires going back to the C1 2, C1 11 and C1 3 PCM pins respectively. With another DVOM I am getting 2.5 ohm which seems a little high but since all three wires are the same so perhaps it is not too high at 2.5 ohms. So, I don't think I have bad wires.

In checking the pulses to the coil, I am not get a pulse on the 4 wire which is for the 2 & 5 cylinders. This van has 405K+ miles on it and about 3 years ago the same situation arose were I was getting no pulse to the same two cylinders, however, the van would start it just ran really rough. I bought a reman computer and the engine has done just fine for a long time.

Problem now is that I am not have an attempt to start whatsoever. Cranks but absolutely no fuel combustion. I am going to check the firing pulse to the injectors this morning. There is sufficient fuel pressure at the rail.

 

dark green orange wire is power from the asd relay which only has power when running and or starting the engine. the other 3 are grounds from the pcm.. Before you did any work disconnect pcm battery anything like that did you check for codes? FYI checking for ohms you do not have things connected to there source. Unplug the pcm then coil then measure the wires from the pcm to the coil that is how you check for excessive resistance in a wire not with it plugged up .

 

I checked the ohms as you described.

All indications I am getting it is the PCM, so I ordered one yesterday.

The power wire lights when the key is initially turned to on (not to start) and then goes off after about one second which indicates the ASD is working.

Two of the ground wires flicker when an attempt is made to start the van. The paired 2 & 5 cylinders do not flicker but have a steady light. That would indicate the PCM is not grounding the circuit to make the plugs spark.

What concerns me that there is something else going on is that the engine will not start at all and it should with only 4 cylinders, or at least it did in the past with the exact same symptoms.