2.3L ('02-'11) 2007 XLT 2.3 no spark

[Jazzer]

Looked in search, found nothing really.

This morning I replaced the thermostat after getting code 0128 I believe it was, insufficient coolant temp. After replacement, I got good cranking but no start. A test light grounded to battery and probe in coil showed no spark while cranking.

I had pulled the positive terminal from the battery before changing out the thermostat. It's possible I may have brushed it against a brake line but I don't remember any sparking.

I pulled the PCM relay (#54) and probed the slots in its receiver, and found 12V in one slot. I installed the blower relay in its place, but no joy.

I can't find wiring schematics online for this engine, so I thought I'd ask you fellas what I should check next?

Thanks for any and all replies!

-Jazzer

 

[Jazzer]

Looked in search, found nothing really.

This morning I replaced the thermostat after getting code 0128 I believe it was, insufficient coolant temp. After replacement, I got good cranking but no start. A test light grounded to battery and probe in coil showed no spark while cranking.

I had pulled the positive terminal from the battery before changing out the thermostat. It's possible I may have brushed it against a brake line but I don't remember any sparking.

I pulled the PCM relay (#54) and probed the slots in its receiver, and found 12V in one slot. I installed the blower relay in its place, but no joy.

I can't find wiring schematics online for this engine, so I thought I'd ask you fellas what I should check next?

Thanks for any and all replies!

-Jazzer

The rain stopped long enough for me to do some more checking. The coil tests OK, I've got 12+V in the center tang of the coil feed connector, but back probing the two commons gives me a solid test light while cranking on each. Seems I'm missing switching, which from reading up means no input from Crank Position Sensor. Sound right?

Fun fact, I hosed the coolant off the frame after replacing the thermostat, nothing crazy, just a slight coupla bursts. I wonder: is the CPS there on the front drivers side of the engine, and could I have shorted it out?

 

[sheep herder]

I think I have this right. If the CEL goes off while cranking, the crank sensor is good. If the light stays on, CPS is bad.

@RonD

 

[Jazzer]

Thanks for the reply, sheep herder, I'll check that out in the morning. It's raining again, and getting dark. Thanks for alerting RonD, I'm sure he'll fly in with his cape and save the day.

 

[RonD]

Hey I haven't worn a cape in at least 3 weeks

CPS generates its own AC volts, ain't much, .5 to 2vAC, so a short would be unlikely

Yes, CEL will go off when Copmputer sees a timing pulse from the CPS, so when starter is cranking the engine over, CEL should go off
If it doesn't then computer doesn't even know you are trying to start the engine, there is no connection between computer and starter motor circuit

 

[Jazzer]

Sheep herder was right, and thanks, RonD for the clue.

I found that when installing the thermostat, I had pinched the wire loom to the CPS. I removed the thermostat, split the loom, and inspected the wires (Orange/red and green/black, metal sheath and bare silver wire). They were crushed but whole, insulation not even broken. I push pinned through the wires on each side of the crush, and got continuity on both. Check engine symbol still wouldn't go out while cranking.

I pulled the CPS and got 451 ohms between its two pins, which fluctuated when I waved a socket over the inductive end. Reinstalled CPS and checked voltage on the CPS's two pins. Meter set at AC 200m, I got fluctuating voltage while cranking. That's as much as I know how to test the CPS, and it seemed good.

Something on the web told me I should have around 1.5 volts on one of the wires going to the CPS, well, I've got 1.47 volts on BOTH (KOEO). I measured resistance between the two and got a really high number, so I think that ruled out a short between the two.

Suspecting the wiring, I ran a long 2 wire cable connected to the CPS's pins, and connected to the original cables wires upstream of the crushed section. Check engine light still wouldn't go out while cranking.

I didn't know whether to scratch my head or my but-tocks. Then I remembered something, checked the CPS, and indeed, I'd put it on backwards. It turns out these Duratecs are real fussy about having the induction coil of the CPS directly over the tone ring. Then I got the check engine light to go out while cranking. I still don't understand why a wire crush would interrupt the CPS signal, but there's a lot of things I don't understand.

I siliconed all my wire punctures, reloomed and taped the cable, and replaced the thermostat and coolant,

Engine is goes vroom.

Thanks guys!

Jazzer

 

[RonD]

Good stuff

 

[Dirtman]

Engine is goes vroom.

This is blatant unlicensed use of a registered trade mark! Expect to hear from my attorney!

 

[RonD]

Don't worry Jazzer, his attorney goes vroom too.......................

Most of the stuff Dirtman has goes vroom

 

[Jazzer]

Nah, nah, you gotta put that little "TM" symbol next to every iteration of the phrase or it's open for public use. You ARE public spirited, aren't you?

 

[Blmpkn]

Pubic spirited perhaps