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??
Thanks...

 

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 :
None

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.

 

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

 

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.

 

I have a 2000 F-150 Screw with a 5.4
I’m getting a 1633 code, I’m get about a 4v reading on Pin#55
i am going to trace it back the best I can, my question is , Since it’s a “Live” power feed alway “ON” what’s the correct voltage it’s supposed to be at all times?
If it’s 12v if I run a 12 v source to it that’s Hot all the time would this cure my problem? I’ve replaced the PCM and everything looks good on the harness, the truck runs and drives, to Odometer work sporadically and the overhead outside temperature and that doesn’t work it is drivable I had to go yesterday to the dealer and get my keys reprogrammed and I don’t wanna have to send back this new PCM because then I’d have to spend more money again having Keyes reprogrammed.
I’m just trying to figure if I run another wire to that pin to the red with white stripe wire and keeping it on a fused power link if it’ll work or cause other problems?
Thanks in Advance for any help

 

You should've started a new thread, but at least it's a similar question.

It sounds like you got a wiring problem or else a ground problem.

You could try bodging in a fused +12v line and see what happens.

If it does work, I would then go through and determine the low voltage problem. Usually low voltage is a grounding problem.

I recently had a low voltage problem on another vehicle and it was affecting the O2 sensor performance and half of my lights. After a bunch of tracing, I found the offending problem which was a grounding lug that the wiring was disintegrating off of. After putting a new lug on, it fixed all my problems and returned it back to OEM.

 

Thank you very much, I’ll check it out for sure, someone got under the dash and looks like added some sort of Trailer lighting relays I’m going to get rid of it and start over and ground everything
I appreciate your reply
Jon