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Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 35832
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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My 2002 F250 7.3 diesel has a error code P0603 ...

Resolved Question:

My 2002 F250 7.3 diesel has a error code ''P0603 Internal controler module keep alive memory error''.I have had computer problems(towed to dealer ) three times and the truck only has 63k miles on it. Can I fix this instead of a dealer, who is very expensive and every couple of years I have another problem?
Submitted: 9 years ago.
Category: Ford
Expert:  Ron replied 9 years ago.


Thank you for asking your question on Just Answer.

The code P0603 is in ost case set due to the performance chip.

If equipped, remove and recheck operation.

If the vehicle is not equipped with a chip, or removing it makes no difference, monitor the voltage on fuse #22 in the interior fuse panel to see if the battery voltage goes away when the problem occurs.

If the voltage on fuse #22 is dropping or going away, check for a loose terminal connection on the PCM power relay. Also try swapping the PCM power relay with a similar part to eliminate a faulty relay.

If the relay is OK, but the voltage on fuse 22 is dropping, suspect an internal problem with the interior fuse panel.

Ron and 4 other Ford Specialists are ready to help you
Customer: replied 9 years ago.
Ron, I don't have a chip or any alterations,I bought the superchips flashpaq tuner only to use the diagnostic capabilities.
Expert:  Ron replied 9 years ago.
Then I would suspect you have an interior fuse panel issue If your having issues.. The 1997 to 2003 are known to leak water from the upper windshield and drip on the interior fuse panel. Have a look at it and see if there signs od corrosion and or dampness.
Customer: replied 9 years ago.
Reply to Ron's Post: Thanks Ron, if it is moisture in the fuse panel is it fixable?When this problem happened today I had driven about 15 miles(no rain)when I noticed the engine sounded kind of strange, then about 4 miles later loss of power then stall. Had a friend tow me home.
Expert:  Ron replied 9 years ago.
I would run thru the test I sent then if it passes the I would suspect the fuse panel even if it hasnt rained today as it could have been building up for some time.