1997 3.9V6

Engine cranks but will not fire. There is no voltage on either terminal to the coil with the key on and hence...no spark at the plugs.

No burnt fuses or fusable links under the hood or in the dash. Checked continuity as well and they are OK. Also checked the Starter Relay in the same box as the fuses under the hood. Swapped out that relay with the AC Clutch relay (I don't even have AC but part numbers were the same)...no difference.

Is there anything in between the Starter Relay and the coil?

I originally thought my starter was bad...I had problems for a few days where the starter would engage, then stop. Had to jog the key a couple of times for the engine to crank. Now the engine cranks but no spark.

What's left to check? Wiring from relay to coil...or am I down to replacing the ECM?

Thanks in advance.

 

I used my Mitchell on Demand 5.8 to look this up. You will find two wires as you described.

One is a Gray wire. This one goes from the coil #1 terminal to the PCM A7 connection, it keeps the same color all the way. It is called the Coil Driver wire. If I am correct this wire should be ground at all times with the key in the run position, remember though this is controlled by the PCM, so if a sensor is out the PCM can cancel the grounding of this wire.

Second is the Dark Green/Orange strip wire from Coil #2 (power in) terminal which also goes to each of the injectors. The injectors are pulsed from the PCM (PCM grounds each lead as needed which completes the circuit and triggers the injector).

Have you had the PCM scanned for any trouble codes? Your problem may not be the coil power wire, it may be another fault causing the PCM to cancel any attempt to run this engine.

 

"Scanned"...I assume you mean hook up a Code Reader? If so...no, I don't have one.

The green/orange wire runs back to the starter relay. I thought this was where the coil was getting its power from...maybe not...sounds like the gray wire according to your info. Maybe the power is coming out of the coil via the green/orng and into the relay???

Guess I'll have to finally break down and get a code reader.

I installed a new TPS about 2 months ago and it had a new Crank Position Sensor installed in March.

UPDATE:

Got a hold of an OBDII reader. Says there are currently no codes stored in the computer. This is kind of strange since my "Check Engine" light was on previously due to an emissions fault. Now I have no Check Engine light on before I even reset the codes. Suspect it reset when I disconnected the battery for an hour to change out the starter...just for the fun of it. I went through a reset anyhow...no change.

I traced the gray wire from the coil to the ECM...no power in it out of the ECM.

I checked voltage from the coil connection again...0 volts to ground, 12V in both legs of the plug when tested across the +ve battery terminal...regardless of key on or off. So essentially these leads are both grounded....???? Now I'm confused even more.

 

[QUOTE=cdnron;1381357
new Crank Position Sensor installed in March.[/QUOTE]

May want to have that checked out, if the PCM cannot "see" where #1 cylinder is then it will not fire the coil. Though all most new still, it may have gone bad or the plug may have come undone.

 

Would that cause my lead to the coil to be grounded though?

Seems to me that I must have a dead short somewhere in the wiring harness.

If the PCM cannot "see" the Crank Sensor would it not spit out an error code?

 

The Dark Green/Orange Wire should have 12 volts going to it. I have not located where the voltage comes from yet but it should have positive power to it.

I do not know if the crank sensor going out would cause the MIL lamp to light or not. From your first post it sounded like the engine ran fine and then the next start it would not run, in this case the computer may not know that the sensor is not working.

Have you checked the fuses in the PDC really well? On mine I saw a fuse that at first looked like it was good then after trouble shooting a problem found it had blown.

 

I pulled all the fuses and checked continuity on them...all OK.

The original problem I had was with my starter. It would engage, then stop and I would have to jog the key a couple of times to make it engage. I figured the Bendix was going on it so I picked up another starter. When I went to drive my van up onto the ramps it just clicked and didn't turn over. I had to jog the key 5 or 6 times to get it to turn over.

When it did turn over it just cranked and cranked...first time for this van.

I found out today that the crazy contact from the battery cable to the starter had corroded and that's what was probably causing my intermittent starter problems. I eliminated it from the circuit and wired the battery cable direct to the starter like it should have been originally.

I wonder if jogging my key a number of times has done something to the PCM????

Appreciate your help on this.

 

Try this switch the ASD (Auto Shut Down) relay with the trans relay. The Dark Green/Orange stip wire comes from the C5 pin of this relay. This relay may be what is bad, hopefully, other wise it is this circuit that needs to be checked. This particular wire powers most of the engines electrical componets. I am sorry it took so long going through the diagrams to find this for you. Let me know how this helps.

The C3 pin should have power to it even when key is not in the ignition.

 

The C3 pin has power to it, as it should.

The relay itself is working. If you pull it out and put it back in you can feel/hear the relay engage. I swapped it out with the A/C relay and the Trans Relay...all work the same.

Still have continuity between my Green/Org coil wire and ground. This is the same situation when I check the same wire as it comes out of the Auto Shut Down Relay.

I can't understand why I haven't blown a fuse somewhere if there is a dead short to ground in the Green/Org wire as my meter consistently tells me.

So I figure I must have a short in the Green/Org wire somewhere or maybe my computer is pooched. Been traveling with work and haven't had time to mess with the thing...I hate like hell to take it into the dealer...I'm sure he'll just end up swapping every electrical component he can find in the thing until he chances on something...and charges me for all the components that were used in the process

 

Ok from your last post it seems that the relay is working fine for you are hearing and feeling it engage. I would make a jumper wire with a fuse installed. Probably 10 or 15 amp fuse, Put a blade terminal (male end like is on the relay) on one end of the wire, the fuse holder and at the end of the wire and aligator clip that you can use to hook to the positive post of the battery. After you make this jumper wire put the blade connector into the C-5 post and connect to the battery, if the fuse holds try to start the engine. If the fuse blows then you know you have a direct short. If fuse holds and the engine does start then I would look in the PDC and see what happened to the wire at the C-5 pin.

Now this particular wire does power the following engine componets:
Injectors - Powers the injectors which the PCM pulses through the other wire on the injectors.
Coil Pack - Powers it.
O2 Sensors -- Powers the PCM detection wire.
PCM C-12 pin (PCM ASD Sensor) Detects that the wire is "hot".

If it is shorted you will have to trace this wire out through the bundles and find it.

One place I would look over real good it the wires off of the O2 sensors. If the wires from them touched the exhaust then they could have melted and are shorting out.