Welcome to FTE! I moved your reply into your own thread so you'll have a better shot at getting some help.

 

Check the fuses. The ECU aka PCM is powered by a fuse that also feeds the fuel bowl heater. If the heater shorts and blows the fuse the PCM will not work. Same fuse powers cigar lighter too IIRC. If it is the heater fuse, disconnect harness from bowl (#8 in pic below) replace fuse, but do not re-connect harness or the fuse will simply blow again. Some people in warmer climes leave it disconnected.

Seem to recall the DLC aka OBDII port also has a fuse that can prevent communication, but that won't cause a no start.

 

Ok I bought an OBD2 breakout box to test the dlc connector values. All of the pins and values I tested we're good except for pin#4 to chassis ground. There was .9v of resistance. Not sure where to look for this problem. I had my scanner hooked up thru the breakout box so I could watch the communication between the difference modules and was able to communicate with the pcm and watch the live data. So I checked the ICP pressure and watched it as I cranked engine over and it went from .26v to 2.95v while cranking. Also noticed cranking voltage dropped to 8.7v which won't allow idm to fire injectors. Also got a p1670 code. Going to put new batteries in and see what happens . I thinking the idm is bad or could be relay for Idm. Going to test/replace relay as needed and go from there. Any thoughts?

 

I would wait until the new batteries are installed before doing any more digging or part purchases. 8.7 VDC is well below the minimum threshold (10.5 volts) to get anything to behave properly.

 

Ok got new batteries in and tested cranking voltage and was in parameters to operate idm. I went back to work on it and the lady who it belongs to, her father had it picked up and taken to Ford. So they told her it was all 8 injectors and it ran. I went and picked it up and it wouldn't run and had to have it towed. Obviously there's more of an issue. I put my scanner on it again and have no communication with ECU again

 

They replaced the injectors? That's like $1500 plus labor if I am not mistaken.

 

Yea the dealership wanted $4770 to do injectors. I had it picked up bc I don't think that's the issue. Was just checking with another scanner I have and found a code for pcm short to ground. Code is U2016

 

Also have code for injector circuit high bank 2 p1294

 

Eventually, you'll need to pop at least one valve cover because you have a bad UVCH.

Our protocol is J1850 PWM, so we use a pin on the OBDII port that almost no other vehicle does. I think it's the pin 2 Battery volts. A weak ground is no good, I'd go on safari for that one and fix it. If they say it runs, was the mechanic the one that failed to get it started when you went to pick it up? If not, maybe they just pulled the ICP sensor plug to get it going in the shop.

 

I tried unplugging the ICP sensor as well to get it started when I first started working on it and it won't start. What ground should I look for to fix?. I will order the valve cover gaskets and the uvch for the injectors as well. I also found some chewed wires by the pcm plug in the driver's side fenderwell so in the process of pulling out the harness and going to take it apart and check for other damage and or corrosion

 

The Injector Drive Module (IDM) is located there, just FYI.


Stewart

 

Someone last summer chased a similar issue. The problem turned out to be a shorted EBP sensor. His ECM could not communicate because of low reference voltage.