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Only .01 volts to ICP KOEO and .07 at idle???

19111 Views 12 Replies 2 Participants Last post by  Cgrigson1
The Truck will just barely run at all and I just replaced the IPR and the ICP and it was running better before I did this. Just learned ICP voltage is supposed to be .24......PlUS I'm getting zero codes from my ScanGauge2.
A wiring harness is $630 and I don't have a clue if it will even fix it.

Does the power wire to the ICP run all the way thru the harness?
Is it possible for me to pull the harness off, inspect for chaffing and if I see chafing is it even remotely possible to trace the wire back after completely unwrapping the harness and then somehow get it all back together?

I'm about to pull my hair out over this damn truck.
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If you could provide specifics about your truck it would be helpful for those trying to help you: Model year, model, engine/trans etc. You can put t his info in your signature as well so it's permanent.

I am assuming you had this problem before you slammed an ICP sensor and IPR in it? Your ICP signal voltage reading is a concern and your specification of 0.24 volts KOEO is correct so there lies your problem. Technically, ICP readings KOEO can be anywhere from 0.15 to 0.35 volts to be considered in spec but typically around .24-.26 is normal. Have you performed any actual diagnostics? Do we have any codes to go by?

I would start by disconnecting the ICP sensor and inspecting the pins for damage, corrosion... then with a volt meter check for reference voltage at the VREF circuit at the sensor - the brown/white wire. If low, unplug the EBP sensor and EGR valve to see if either of them is pulling the voltage down and move the harness around going from the sensor all the way back to the PCM. If still low, then check the continuity of all three circuits from the sensor to the PCM.

I attached the wiring diagram page from the 2005 manual to help you but the wiring has changed a couple of times depending on model year so I will change the image to the correct year if you can provide that information. It makes a difference!!!
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Here are the correct diagrams for your 2004 6.0L. I included the PCM connector face diagram for you as well. Connector C1381c is the middle connector on the PCM.

Verify the circuits as we discussed and add the throttle position sensor, EGR and EBP sensors if you need to disconnect or measure voltage at those sensors. It does not matter if the EBP sensor was deactivated with the engine calibration from an early recall - the circuits are still connected and can cause problems. (in case anyone is wondering)

An early 2004 engine should have the ICP located on the HPOP cover in the rear of the engine. They were known for ICP sensors that often damaged the harness and connector due to oil migration. Inspect that connector and wiring - if damaged replace the connector with a service pig-tail.

Since you were repairing the injector harness at #8 you were working right in the same area so reinspect your work in case you caused this problem by damaging something accidentally. You said this started after that repair right? It happens.

As for the HPOP, the early pumps are a high failure rate item. BUT the pump won't affect your KOEO voltage. I am getting the impression you know that though.


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Then it is not technically an early 2004 if the ICP is on the right valve cover. Soooo we revert to the prior diagram...
I changed back to the original in the lower post. Has no highlighting. Its basically the same. And ahh, Doc participates in these forums to give back... its no trouble at all and there are dozens of others who give of thier knowledge freely. That is what this community is about ;)
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