2003 6.0 Excursion: FICM or Injector Harness?

[428F250]

I have a 2003 Excursion with a 6.0L Powerstroke. It recently developed a misfire on cylinder #2. I bought an AutoEnginuity Scanner and did lots of troubleshooting on it this weekend.

I've read a lot of good information here, but I haven't read about the exact same problem (i.e only one injector affected). My basic question is whether to suspect the FICM or the injector harness.

Here is what I have done so far.

1. Scanned for codes: got P0265 (#2 inj short to ground) and P0266 (#2 reduced output in power balance test.

2. Ran the injector buzz test: got P0265.

3. Wiggled the injector harness with the engine running, but the misfire persisted.

4. Removed the injector harness and rang it out. All four wires for injector 2 had less than 0.5ohms between the injector connector and the FICM connector and greater than 10,000ohms resistance to ground.

5. Ohmed out the #2 injector itself. Got 0.8 ohms between pins 1 and 2 and 0.8 ohms between pins 3 and 4. Greater than 10,000ohms between all other pin combinations and from each pin to ground. I think this rules out the injector itself as the culprit.

6. Checked the FICM voltage with the AE with KOEO, cranking, and KOER: Always greater than 46 volts (usually 48). This leads me to believe that the FICM power circuits are good.

7. Checked the ICP bias voltage with KOEO (0.15V) and KOER (1.15V). ICP actual and demand pressures both about 850psi idling (CA emissions).

8. Checked the IPR duty cycle with KOER at idle (~30%). #7 and #8 lead me to believe that I don't have a HPOP problem.

I've read in a bulletin from International about the FICM that if it fails, it will likely cause a no-start situation or erratic misfires affecting all cylinders. It also said that the early FICMs had individual close circuits for each injector, whereas the later FICMs have one circuit for four cylinders. I have an early FICM, so I suppose it is possible that only one open or close driver could have failed. I would like to know if others have had the FICM fail in this way (i.e. only one injector affected).

I've also read that chafing of the injector harness is very common (although I didn't see any visible evidence of this, my harness ohmed out OK, and I couldn't get any change from the wiggle test.

With all of this in mind, would you suspect the FICM (affecting only one injector) or the harness?

One other question: can I replace the 2003 injector harness (3C3Z 9D93 AA / 1843796C92) with the 2005-2007 harness (5C3Z-9D930-AA / 1870390C91). It seems to me that they should have the same pinouts. The newer harness is about 1/2 the price.

Thanks in advance for any help you can provide.
Jay

[428F250]

I moved the #2 injector connector to the #4 injector and the P0265 DTC moved with it. I think that confirms that the #2 injector is not the problem. The #4 injector connector wouldn't reach the #2 injector, so I couldn't verify it that way.

I also ohmed out the harness again completely and couldn't find any problem with it. This made me really suspect the FICM, but I was still suspicious since it was only one cylinder, and I've heard that the injector harness problems can be intermittent.

I tried a couple of other things that were interesting. I disconnected the #2 injector connector, ran the buzz test and got P0264 (open) on one #2 injector circuit and P0265 (short) on the other #2 injector circuit. Again, this confirmed the problem is either in the harness or the FICM. Then I disconnected the FICM harness X2 connector from the FICM and ran the injector buzz test. This time I got open circuit DTCs on all four cylinders on the X2 connector, but NO SHORT CIRCUIT DTCs (P0265 went away)! This made me think that the problem was in the harness.

I bought a new harness, installed it, and P0265 is still there.

Today I shipped my FICM to FICMRepair.com to have it fixed.