Keep Alive Power voltage too low?? - F150online Forums

Go Back  F150online Forums > F-Series Trucks > SuperCrew
Keep Alive Power voltage too low?? > Keep Alive Power voltage too low??

Keep Alive Power voltage too low??


Old 11-09-2002, 03:51 AM
Junior Member
Thread Starter
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??
Reply With Quote
Old 11-10-2002, 12:20 AM
Technical Article Contributor
Join Date: Jun 2002
Location: Under the flightpath of old ORD 22R
Posts: 10,510
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; 11-10-2002 at 12:33 AM.
Reply With Quote
Old 10-01-2008, 12:03 AM
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
Reply With Quote
Old 11-02-2015, 12:54 AM
Junior Member
Join Date: Nov 2015
Posts: 1
PCM, P1633, fuse 2, 5 amp

I bought a used 03, the 4.6 with 87,000 miles. The code came up within a week of the sale. After reading the code I went back to the dealer and didn't get much help. So I dug in and read everything online. Sscully is correct it is pin 55 and the wire is red with a white stripe at the pcm connector. There was another post someplace, I think it was a mustang form, but somebody said to check the thru firewall connectors on the driver side. There are 3 and the poster said to look at the bottom one. 6 inches up that harness i noticed a sharp bend in the harness at the bracket for the power distribution box. Also someone had been in there before me because I noticed the harness had been taped back together. Thats where the short was. The wire was separated/burnt so it was an easy one to find, red with a thin white stripe. Someone put a 20 amp fuse in the number 2 spot.
Reply With Quote

Related Topics
Thread Starter
Last Post
2004 - 2008 F-150
03-23-2016 10:20 PM
Trucks For Sale (2004 - 2014)
01-29-2016 12:00 PM
Shane Henson
2004 - 2008 F-150
08-22-2015 09:58 PM
2004 - 2008 F-150
08-02-2015 04:04 PM
1997 - 2003 F-150
07-10-2015 11:04 PM

Thread Tools
Search this Thread
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


All times are GMT -4. The time now is 03:25 AM.

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to and affiliated sites.
  • Ask a Question
    Get answers from community experts
Question Title:
Your question will be posted in: