97 mercury villager 3.0L

I came back from some vacation time to this mercury villager in my shop. From what I understood from the other techs is that they replaced the battery and a cable end and now it's a no start no spark but the coil will produce a single fire event after the key is shut off. I confirmed this condition. Had battery voltage on the feed wire and did not drop out while cranking. The control wire was not consistent at all. Showed battery voltage plugged in and while cranking would drop to about 4 volts then back to 12 then to ground voltage and back to 12. Unplugged crank test showed consistent battery voltage on the feed wire and a constant ground on the control wire. I'm told the coil was replaced which did not fix it so the old one was put back in. Also checked the ICM. Feed wire and ground are good but nothing on the signal wire. Not sure what to make of the results I got at the sub harness for the cmp sensor. Checked both the 1 degree and the 120 degree signal wires and had ground voltage on both while cranking. I should also mention that I did confirm good control to the injectors. Scratching my head on this one guys. Help would be greatly appreciated

Hi Randy.Martin, welcome to the forum!
Just glancing over the service info here...
There's a power transistor on the A/C compressor bracket between the coil and the distributor. I'm thinking that's the ICM you checked?
The power should be coming from the ignition. The transistor should have a dedicated ground (G107). You should be able to load this ground with a bulb or something to prove it's integrity.
The PCM will turn on the base of the transistor based on input from the cam sensor. How are you testing the signal wire at the power transistor? Scope? Meter? I'd expect some kind of square wave on that wire. 0-5v, 0-12v, it's not clear exactly what the turn on signal will be.
As far as the cam sensor, ground on the signal wires while cranking isn't good. Those look like they should 5v square waves. Obviously the lack of mechanical movement would result in no signal on both wires. I think you could rule out a short to ground since it's unlikely both wires would be shorted (however not impossible). Or possibly just a junk cam sensor. Did you check the power and ground wires at the cam sensor? Should be 12v feed from the PCM relay (probably key on and cranking), and constant ground (g108) plus your two signal wires.

Update: checked the 1 and 120 degree signal wires for the cam sensor. Signal is present but only produces less than a volt and doesn't show the square wave I should see. Unplugged, the 5 volt reference is present on both wires. Could be wrong but the call I'm leaning towards is a bad dist but still doesn't explain the weird single fire event from the coil after the key is shut off.

Yes the transistor (icm) is what I was checking. Also using a scope. The vantage ultra. Verified power and ground at the sensor as well. Have not checked for mechanical movement as I was working by myself but that is what I'm leaning towards. Thanks for your input. I will do more checks and will update my results

Sounds like you've got it nailed down. Is the cam sensor part of the distributor on this one?

There is mechanical movement of the dist. The cam sensor is part of it, yes. New dist would be the fix for this if I'm not mistaken

Good news is that a new distributor fixed the spark issue. Bad news is that I got bad info from my fellow techs and the vehicle still doesn't start. It was my assumption that they checked fuel pressure to verify fuel but in fact they did the old fashioned spray in the intake method which was invalid since spark was missing as well. So, glad to say that spark is no longer the issue, but still have to chase another problem. How it goes sometimes in the mechanics world. Thanks for the help on this one. It was greatly appreciated

Well it was a good diagnosis of the no spark issue!
Thanks for keeping us updated.

Okay so I'm kind of back to square one on this villager. Still a no start. Found out its also a no comm even with the Nissan da5 adapter so scan data is no help to me so I'm going through all the critical inputs and checking off boxes trying to narrow it down. Ect checked good and just for peace of mind even did a by pass test (unplugged, pulled signal to ground simulating hot coolant temp. Fan kicked on. Great!) Camp sensor was already replaced with the new dist. Double checked fuel pressure (45 psi. Again just for peace of mind measured pump current and pump rpm at the relay. Roughly 4 to 5 amps on the peaks. Rpm is about 6500) checked compression, a lil low but enough to start, 110 psi. Only thing I haven't exhausted is checking the crank but from the info I read it's only used to monitor fluctuations in engine rpm and turn the injectors off and on accordingly. Or severely plugged exhaust.

Sorry I kind of left you hanging there, been pretty busy with work and all that jazz...
So what's going on now? no fuel pump activation and no communication? Or is the pump working but low pressure?
Are you still getting spark and injector pulse?
Have you tried firing it on starting fluid since you changed the distributer?
How about checking for 5v at the TPS or something like that?
This is great video giving the rundown on a no com. It doesn't mirror your symptoms, but the no communication testing will apply.

The fuel pump was working. 5 volt reference was there. And even though it cranked okay I did check the timing (amp probe on the battery cable going to the starter and ignition probe on the dist plug wire) and was dead on. Still had good spark and injection pulse. I unfortunately had to send this one out the door and told the customer to take it to the dealer, customer needed an answer and couldnt give em one. I will be following up with this customer to see what the final fix will be and will use this as a learning experience.