[eewarman]

Hello Everyone. I am a new member, but have been keeping up with the 7.3L forum for about 2 months now.

My truck had the symptoms of the UVC harness problem. Before I could get it home, the engine died. I purchased the retainers from Ford and added them. The passenger side was definately unplugged. I reassembled and the truck will not start. I had it scanned with the Snap On scanner and verified everything was working. The high pressure oil, fuel pump, etc... The fuel filter has 10K on it.

I ran the injector buzz test and both banks showed open with codes 1293/94. It failed the test. I asked the scanner owner if the PCM was bad. He said with the amount of communications with the scanner, probably not. I have ohmed out the injector harnesses and everything is fine.

My question is how to test the IDM. No one at the dealer seems to know, they just want to sell a new one. Also, (ashamed to say) I have looked everywhere for it. Where is it located on the 99? I knew where it was on my 96.

Thanks for the help.

 

[MrPlowJr_EZ_V]

To find the IDM, You will need to remove the drivers side fender liner, and look up and back toward the firewall you will see it.

as for test procedure I have only ever changed it with one that is known good...

You might want to ohm out the wires going from the IDM to the engine/injector harness. and make sure you check all the pins on the harnesses, I've seen alot of loose connections where the harness ohms out fine, but the pins aren't making good contact.

I hope this helps.

Kory

 

[klhansen]

I agree with what Kory said.

Check your wiring before buying an IDM. The codes you got pertain to only 2 wires, each one going to the center pin of the VC gasket connector. Find the same wire color at the IDM connector and check for continuity.

Also, did you eyeball the VC gasket connector for burnt pins? The center one on each side carries all the voltage to the injectors, and if it's burnt or open, the whole side is dead.

Good luck with it.

 

[eewarman]

Kory and KL,

If i spin the engine over as if trying to start it, should i be able to measre the 110 volts DC on the center pin of the valve cover harness? Just curious. Thanks for the help.

 

[dwelch1]

check out e-bay and watch for IDM's maybe you can get one cheaper than what the dealers wants for one.

 

[ken527]

I had a no start condition on my 2002 Excursion and had it towed to a dealer and they found the wire harness rubbed raw and shorted out in the fender well area.

 

[klhansen]

[ QUOTE ]
Kory and KL,

If i spin the engine over as if trying to start it, should i be able to measre the 110 volts DC on the center pin of the valve cover harness? Just curious. Thanks for the help.

[/ QUOTE ]

I don't think you even need to turn the engine over, just have the key on. AFAIK, the IDM puts out voltage continuously at the center pin and completes the circuit thru the injectors by grounding the individual injector wire. I'd be careful about measuring it, though. It brings back memories of being zapped by the bare spark plug leads on the old Model A /ubbthreads/images/graemlins/shocked.gif

 

[eewarman]

KL,

Will the later model IDM (XC3Z-12B599AC) work for my early 99 model truck?

Thanks again for the help.

 

[JimmyDee]

[ QUOTE ]
I have ohmed out the injector harnesses and everything is fine.


[/ QUOTE ]
Keep in mind that with the voltages the injectors are fired by, faults in the harnesses may not show up with a VOM. At best, you are pushing 9 volts but more probably 1 1/2 volt to try to find a fault in the harness. Operating voltage is closer to 110 volts. You can get a false reading.
Jim

 

[eewarman]

[ QUOTE ]



[/ QUOTE ]
Keep in mind that with the voltages the injectors are fired by, faults in the harnesses may not show up with a VOM. At best, you are pushing 9 volts but more probably 1 1/2 volt to try to find a fault in the harness. Operating voltage is closer to 110 volts. You can get a false reading.
Jim

[/ QUOTE ]

Jim,

Is there a way to get around this problem? Just a visual test?

 

[klhansen]

[ QUOTE ]
KL,

Will the later model IDM (XC3Z-12B599AC) work for my early 99 model truck?

Thanks again for the help.

[/ QUOTE ]

Not sure, but I've heard that they are all the same.

 

[JimmyDee]

[ QUOTE ]
Is there a way to get around this problem? Just a visual test?

[/ QUOTE ]
That is how I found my problem with the harness.
Jim

 

[JimmyDee]

[ QUOTE ]
Jim,

Is there a way to get around this problem? Just a visual test?


[/ QUOTE ]
Yes, you could megger the harness but it would have to be disconnected from both ends. The higher voltages could do damage to the injectors and or the IDM. Don't know of any other way.
Jim