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Old 11-09-2002, 02:51 AM
Junior Member
Join Date: Jan 2001
Location: Pearland, TX USA
Posts: 5
Unhappy Keep Alive Power voltage too low??

I have a '01 Screw w/ 55K miles. Recently the Service Engine Soon light came on and stayed on for a week. Autozone read this code P1633 which means "Keep alive power voltage too low."
No one there knew what this code meant nor did they have a service manual for my vehicle. Would someone translate this and tell me the best solution for this problem??
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Old 11-09-2002, 11:20 PM
Technical Article Contributor
Join Date: Jun 2002
Location: Under the flightpath of ORD 22R
Vehicle: 2006 FORD F150
Posts: 10,264
From the Ford 2001 Service Manual

DTC : P1633 - Keep Alive Power Voltage Too Low
Description :
Indicates that the Keep Alive Power (KAPWR) circuit has experienced a power interrupt.

Possible Causes :
Open KAPWR circuit
Damaged PCM
Intermittent KAPWR Circuit

Diagnostic Aides :

This is from the Service manual, I have not seen this myself, nor do I know how well the poss causes are.

The only part I see in the electrical diagram for the KAPWR ckt is on pg 25-9, the PCM. It is pin 55 ckt 729 red / white stripe.
If you don't know the PCM is located under the hood, pass. side, between the firewall, and the battery ( page 151-21, C174 )..
Sounds like something serious to me, the electrical manual gives no additional wiring locations for this, so it might be internal to the PCM.

Sorry it might not be much help.

Good luck

Good luck.

Last edited by SSCULLY; 11-09-2002 at 11:33 PM.
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Old 09-30-2008, 11:03 PM
Junior Member
Join Date: Sep 2008
Posts: 1
i have a 2001 ford f-150 with engine light on. p1633. i tried a couple mechanics but know one has a clue how to fix it. its a vehicle with flood damage and has over 100k miles. does any one maybe have a solution to this problem. i checked the battery and some other minor things. help would be appreciated! thanks
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Old 09-30-2008, 11:03 PM


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