99 EB 5.4, crank/no start - help!

[Hugh Jass]

When I had a no-start condition it was my Crank Position Sensor.

I followed the diagnostic procedure outlined at this website: Part 1 -How to Test a No Start Condition (Ford 4.6L, 5.4L)
I was able to borrow many of the tools at AutoZone.

Good Luck!

 

[dd350]

Thanks, HughJass. I'll run through that at some point this weekend. I was only able to identify one more fuse associated with the PCM, PDB #15, that I haven't tested yet either.

 

[Bedrck47]

dd350 Quote "I was only able to identify one more fuse associated with the PCM, PDB #15, that I haven't tested yet either."

FYI

Fuse #15 in the PDB (Under Hood) has nothing to do with the PCM Its for the running boards.

However fuse #15 in the CJB (under dash) is associated with the PCM thru the Brake pedal position switch Fuse #15 also provides power to the GEM

 

[dd350]

Yeah, checked that one too. It was fine.

 

[Bedrck47]

How did you check it??

 

[dd350]

Pulled the fuse, observed the interior lights going out, tested it with multimeter, continuity confirmed. Reinstalled the fuse and observed the interior lights coming back on.

A couple nights ago I also remembered that I left my diagnostic tool plugged in to the OBD-II port for about a week before I went out and pulled it off and recharged the battery from the significant drain it had caused. I don't know if being connected that long can cause a problem, but it's the only thing I can remember happening between the time that it started and ran fine until a few weeks later when it wouldn't, and the OBD-II port no longer works.

 

[Bedrck47]

One thing I have noticed in all off your testing is the you have pulled all the fuses you mention and have looked at them and tested them for continuity. That tells me you are using a ohm meter. That may be a good test for fuses but it doesn't show what voltage you have at the fuse. I understand that if the lights went out and then came back on that would show voltage present. But that was for the last fuse you tested not for any of the other fuses. A low voltage condition can cause problem but a no voltage condition can cause bigger problem. I would suggest the you test for voltage rather than continuity. You have only tested a few of the fuses that can cause the problem your having so again do a test for voltage. Refer to the following link.

http://www.expeditionforum.com/f16/fuse-testing-101-a-24587/#post200023

As I posted earlier there are at least 17 fuses associated with the PCM some of them are for various inputs and won't have anything to do with the problem you are having but some of them do involve the cranking/starting portion for the PCM.

What prints/manual are you using?

 

[Bedrck47]

In your original post you stated

4. tested PDB 15A fuses 23/24, both visually and with continuity. Good.
5. tested PDB 30A fuse 2, both visually and with continuity. Good.
6. tested PDB 15A fuse 18, both visually and with continuity. Good.

What is/was the input and output voltage at those 4 fuses??

 

[dd350]

Interesting thought, I'll go test it today and report back.

 

[dd350]

Test results

Ok, so here are the test results.

KEY OFF
#2: 12.5v
#18: 0.0v
#23: 0.0v
#24: 0.0v

KEY ON
#2: 11.7v
#18: 0.9v
#23: 0.9v
#24: 0.9v

Pretty sure something's seriously wrong on 18, 23 & 24.

 

[Bedrck47]

what prints are you looking at and why do you think you have no voltage on #18, #23 and #24 and BTW fuse #18 is also for the fuel pump and fuel injectors and without fuel the engine will not start

Now maybe you should have listened when you were asked to check fuel pressure.

It takes THREE things for a engine to start Actually 4 things it takes air, Fuel and Spark and the 4th item is good voltage You have 2 of the 4

The reason you don't have any voltage on 18, 23 AND 24 is due to the PCM relay not pulling in to allow voltage to those 3 fuses

Look at your prints and figure out why the PCM relay isn't pulling in. It is due to three things A bad PCM DIODE, or A bad relay, or a blown fuse. My money is on the fuse.
because you have already swapped the relay and diode.

 

[stamp11127]

Check fuse 111 in the battery junction box - it is hot at all times - need voltage reading

If above passes, check fuse 30 in the central junction box, ign on run - need voltage reading

If those pass with battery voltage, check the socket for the pcm power relay blade 86 with relay removed. Should read battery voltage with ign in run.
Relays are usually marked with the blade numbers. If not, bedrck or I can give you the location.

 

[Bedrck47]

My Money is on fuse #30

 

[dd350]

Fuse 111 was good and read 12v. Blade 86 of relay 304 was 0.0v in Run. Fuse 30 was good, but I forgot to check voltage reading, I'll go back and check it again first thing in the morning.

 

[Bedrck47]

Pull relay 304 and insert you voltmeter into pins 85 and 86 turn the key to run and see if you read 12 volts.

 

[stamp11127]

You are checking for the presence of voltage at the socket the relay plugs into, not the relay once it is removed from the socket.
Normally Ford supplies power on blade 86 and according to the diagram that still holds true.

If fuse 30 has voltage on both sides and the socket doesn't at 86, then pull the pcm diode out of it's socket and check for voltage there.

Does your meter have a setting for testing diodes?

 

[dd350]

Had a feeling I'd be questioned on that, so I took a pic:

 

[Bedrck47]

What is the voltage from pin 86 to ground with the key on
Also what was the voltage on fuse 30

 

[Bedrck47]

What you need to do is put one lead in the slot for pin 86 and the other lead in the slot for pin 85 and with the key on you should read 12 volts

 

[dd350]

Ok, fuse 30 had 12v on both sides. PCM diode 501 had 0.0v on both sides. The voltage on pin 86 was 0.0v.