PCM problem

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Nov 15, 2016 | 08:51 PM

Montanafisher

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PCM problem

I acquired a high dollar diagnostics computer. PF diagnostics I believe is the name. Anyway i tried.hooking up to 02 7.3 and it won't connect. Connects and communicates fine with a number of other vehicles. Including same year 7.3 my fuses and cigarette lighter are all good. Truck starts and runs but cruise control doesn't work. So my question can a pcm be bad to not establish communication but still start and run truck.

Nov 15, 2016 | 11:28 PM

aawlberninf350

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From: Elk Grove, CA

If the truck runs the PCM is good. At least good enough.

I'd lean more toward the OBDII port being bad, even if the fuse is good.

Got any details on this PF diagnostic thingy?

For the cruise maybe the brake switch is disconnected. There was a recall for faulty switches that caused fires and perhaps the PO disconnected it and never got the recall. Plop your VIN in at the link below to see if the recall was done on your truck.

Ford Field Service Actions

Nov 15, 2016 | 11:45 PM

Montanafisher

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PF stands for pocket fleet. More on the program and software can be seen at diesel laptops.

As for troubleshooting the obd2 connection is there a process of what to test and proper values to see.

I will check brake switch, but if I can get computer and pcm to communicate I can watch all the switches and sensors on there I believe

Nov 16, 2016 | 10:43 AM

pirschwagon

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Quote:

Originally Posted by Montanafisher

So my question can a pcm be bad to not establish communication but still start and run truck.

Yes.

Check Pin#16 on the OBD Connector for power. This should have power all the time key in / or out. There are only eight pins used of the 16.

And, Just because the Power Port works does not eliminate a wire issue at the port.

PWM PCM OBD-II Connection on Diesels (7.3L) uses only 8 of the OBD-II Pin Points

Pin# 4 is Chassis Ground. You should have no resistance between Pin#4 and the Chassis Ground.
Pin#5 is Sensor Ground - You should have no resistance between Pin#5 and any Sensor.
Pin#16 (Top Row, First pin OR Bottom Row Last Pin (Narrow End)) is 12vdc and should be active (Hot) with KOEO.

** You should see 12vdc KOEO between Pin#16 and Pin#4. **

Nov 16, 2016 | 03:28 PM

garydmundy

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From: Banner WY Pop 42, yes 42

For cruse control, check and see if your 3rd brake light works (the one on top behind the cab). If it is out, the cruse control won't work. I know, it sounds strange but it's wired that way.

Nov 25, 2016 | 06:10 PM

MoBill122

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From: Woodstock, GA

Agree with others, check the Deactivation Cruise Switch on the brake Master Cylinder. There was a recall on this switch and its blamed on numerous vehicle fires.