Auto Electronics: P1633 Code on 2001 Lincoln Mercury, engine wiring harness, powertrain system

Question
Check engine light went on and bought code reader.  The code was p1633 on my 2001 Lincoln Continental.   A few weeks ago, there was very cold weather and I had a real tough times starting the car,  was using Sam's Club gas too.  I thought I was going to run down the battery, but it finally start.  Then a few weeks later, the check brake light went on..the lights were fine and it went off by itself.  Then last week the check engine light went on. I went to the box in the engine, pulled and cleaned all the fuses.  It went out for  a few days and came back on.  I even went in to the local shop today for an oil change.  They battery and alternator checked okay...they did not see any code.  I drove away happy and a few hours later, it came back on.
Any thoughts would be appreciated and keep my out of either the nuthouse, poor house or both.
Thanks,
Mike

Answer
Hello Mike,

Ok so, this is going to be a lengthy answer, I will try to be as specific as possible, if at anytime anything is unclear, please email me back using the followup option.

OK, OBDII DTC P1633:

This is a powertrain system code, Manufacturer Specific within the computer output circuit system.

Specifically P1633 is the Ford/Lincoln KAM (Keep Alive Memory) Voltage Low Code.

Follow the below steps IN ORDER to rectify and fix this problem.

1. Check The Battery Terminals -  Check Both Terminals for Corrosion and/or play (looseness).  A bad or loose connection at the battery can cause this code. Correct problems as needed.  If no problem found, move on to step two.

2. Check Engine Compartment Wiring Harness - Check the Engine Wiring harness and connectors for damage and/or corrosion.  Ensure that the harness is properly routed and not too close to the ignition or exhaust components which can cause damage or wire integrity failure.  Correct problems as needed.  If no problems found move on to step three.

3. Check Keep Alive Power Circuit (This part can get complex and I recommend having this performed by a licensed Automotive Electrician)

 1. Turn Ignition switch to off and remove the key.
 2. Disconnect PCM (Powertrain Control Module) Connector, inspect for loose, damaged or
    corroded terminals.
 3. Using a DVOM (Digital Volt/Ohm Meter), Measure the voltage of KAPWR (Keep Alive Power)
    Circuit between Ground and PCM harness connector terminal No. A44 (LS Model) or Terminal
    No. 55 (All other models)
 4. While observing DVOM wiggle and bend small sections of the harness between the PCM and the
    dash panel.
 5. If voltage is 10.5 continuous or more, move on to next step.  If voltage drops to less than
    10.5, isolate open in KAPWR Circuit and repair as needed.  Once complete move on to step
    four.

4. Check for repeat Code P1633.  (NOTE:  Before beginning this step make sure you have cleared all codes, including continuous memory codes out of the computer.)

 1. Reconnect PCM Connector
 2. Start the engine and allow it to idle and reach normal operating temperature.
 3. Perform KOEO (Key on Engine On) on-demand self test.
 4. Retrieve Continuous Memory DTC Codes from the computer.
 5. If P1633 is Present, Replace the PCM (Powertrain Control Module).
 6. If any other codes are present, service as necessary.
 7. If no DTC Codes are present Testing and repair is complete.

Good Luck.

Please keep me advised of your progress, and let me know if you require further assistance.

Thank you.