Hey everyone. Just bought a mustang and trying to get her running. It will turn over and not start. Im getting 40 pounds at the fuel rail and I cleaned the throttle body and IAC to start. Replaced the fuel filter and the fuel pump is brand new. So I started testing my circuits and think I’m onto something. Using my circuit tester all fuses under the hood are good and have circuit and 12v when it’s supposed to. I check the circuit on fuses under the dash and when I get to fuse 35 (with the key on) my circuit tester doesn’t light up. Put a meter on it and I have no voltage. Fuse 35 in box under the steering wheel controls Shift lock actuator, PCM, speed control servo, and ABS module. I’m assuming it should be 12v with key on because the PCM needs power to control engine to start but I can’t find a full wiring schematic for that fuse. Don’t really know where to go from here.

Any help or suggestions from here would help a ton! Thanks

 

Update. Found wiring diagram for speed control servo that shows fuse active on breaking, and tested circuit while holding break and confirmed circuit is good, so that's a bust. Back to square one on why it wont start. Going to test ohms on cam and crankshaft position sensors next..

 

What’s the history on the car on why it’s not running? The SN95 platform is know to have PATS fits that prevent the car from starting if the pcm or keys have been swapped out and not properly reinitialized and paired to each other.

is the theft light on the dash flashing? If it is, it’s more than likely PATS related.

 

No the theft light has its normal flash before the key is put in but after I put the key in it goes away. I originally thought the same thing but the symptoms don’t add up for PATS. I have plenty of fuel pressure, and I can hear the fuel pump kick on. I’ve been going through the electrical system and wiring looking for something and so far the only thing I have found is a wire on the crankshaft position sensor has broken insulation exposing some of the wire where the connector is and has a bend. I need to check for continuity to make sure it isn’t broken.

 

Even if it's not broken and has continuity, you could have interference being introduce by it being exposed. If the vehicle doesn't have a solid Crank signal (at least on Fords), the PCM may not be allowing spark at the coils. Have you checked for spark?

 

Update: this rabbit hole goes deeper than I thought. I am getting around 1 to 2v to the pcm.. Nowhere near 12v. All of the grounds that I've checked seem good and have very low ohm resistance. I do have some voltage drop in some of my fuses under the dash when key is in run. The voltage is fine when the key is in acc. When I try to crank its flooding out so bad that i'm getting gas in my oil, so the PCM is giving 100% to injectors. Not really sure how to trace the problem at this point.

Spark is good and I replaced the plugs, IAC, FRPS, cam sensor, crank sensor, and FPDM before I discovered the PCM voltage. My battery is toast and had to get all of my readings with a battery charger hooked up to it. Not sure if that can affect it or not but I plan on replacing it tomorrow. Any ideas where to go from here?

 

what year is the car? Manual or Auto? Engine size?

Maybe someone can pop up with a wiring diagram for your Engine harness.