02 taurus code p1633

2002 taurus 3.0 OHV.
Check engine light came on last week. Ordered maxiscan ms300 code reader on amazon. Had some rough idle today, Code reader came and code reads 1 error, P1633.
Anyone know anything about this P1633? From what I see on the net it could be the cars computer. Only how can it even give the code then :banghead::screwy:?
Im confus:confused:
Used the code scanner to erase the code and it comes right back.
Thanks!

I certainly wouldn't jump to a bad PCM conclusion from that diagnostic code.

Per the factory service manual, that code is "P1633 - Keep Alive Power Voltage Too Low." Also according to the manual, the code "Indicates that the Keep Alive Power (KAPWR) circuit has experienced a power interrupt." While the PCM is a possible cause, the more likely sources of the code are due to issues with the KAPWR circuit.

My suggestion would be to start with the battery cables and connections. Make sure they are clean and secure. If the battery is near 4-5 years old, consider replacing it.

Does your MS300 scan tool have a datastream mode that will allow you to monitor the Keep Alive Power voltage and/or charging system voltage? What voltage is the tool displaying?

-Rod

Remember, it's just a diagnostic tool. Not a cure all. Too many do the scan and replace parts with no trouble shooting.. shorod has good advise.

Thanks
The battery is only about 2 months old and good connection (at battery) and I checked with voltmeter, the alternator is charging it. I looked around for any damaged wires in engine compartment,nothing stood out. I had put in a new starter about a month ago so the battery was disconnected then but the light only came on about a week ago.
All the fuses are good.
I think the ms300 has a datastream mode but I didnt see it when I ran the scan. I will have to read the manual:crying:,
I will get that info and post it here.

OK, the scanner (autel maxiscan ms300) does not have a datastream mode and my voltmeter is analog.
Is there any point in disconnecting the battery for a half hour and then driving it in a way specified in the car owners manual to reset the PCM? Im guessing no?.

Correct, no point in doing that since using the MS300 to clear the diagnostic codes resets the drive cycle anyway.

Also, I wouldn't be so quick to rule out the battery and charging system yet just because the battery is new. It was likely disconnected when the new starter was installed, so there's an opportunity for a loose or damaged cable.. Plus, depending on how rough the person got when removing the cable or retightening, the post could be broken inside the battery case causing an intermittent connection. Also, I've seen batteries fresh off the shelf that had open cells or internal intermittent connections. I'd suggest spending a little time doing a wiggle test on the battery, battery connections, alternator connections, and connection to fuse panel. You could also monitor the system voltage while driving and make sure you are not getting drops when you step on the brake pedal, turn on headlights, or hit bumps in the road. If you could find a digital multimeter with Min Hold feature that might make the task simpler.

Also, check the manual on your MS300 to see if it can access the freeze frame data. If so, check that and see what the parameters show. Maybe you'll find this only happens when the car is cold, then you might be able to focus on what the charging system does when the starter motor is engaged.

-Rod