2001 Lincoln Continental p1633 Code Mystery

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Lamf77

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Brand new to forum. I thought I could get concise, not bias advice here and I appreciate any replies.
I live in Chicago. I purchased a 2001 Continental with 70,000 miles in 11/2009. The person I bought it from installed a new Interstate battery.
A few months back, the coldest day of the year, I had a really difficult time starting my car. The lights really dimmed, lots of cranking etc. but it finally started. No issues since.
Then 3 weeks ago, the check brake lamps warning went on in the instrument console. I checked the brake lights, they were fine. I reset the warning. This happened about 3 times, it seemed hitting the brake (obviously) triggered the warning. After about 3 resets in a period of 2 days. No more issues. No more brake lamp warnings.
Then, about 2 weeks ago, the check engine light went on. The dealer wanted $129 to assess anything electrical, so I made the investment in a code reader.
The code was P1633 PCM Low Voltage.
I disconnected the battery, and checked all the fuses and relays and obvious grounds. When I restarted the car, the light was off for a few days, but then came back.
I took the car to the Sams Club where the battery was purchased. They ran some tests and said battery, alternator and starter all tested fine. They could not see a problem.
I was recommended to buy a Optima Yellow Top because I do have a after market stereo which has been in the car for over a year. They said even though the battery tested fine, the deep cycle would be better for my car.
Well it was not, so I simply had them put the old battery back in.
Previous to my changing the battery, the light would be off, whenever I started the car the next day; but would eventually come on within 10-15 minutes or an hour. If I stopped and started the car again, sometimes it would still be on, other times it would be off, but then come on again in a few seconds. Now since they changed the battery, it comes on with seconds everytime I start the car.
Finally, today, I took it to a local autoparts store. They verified the code and also the fact the battery, alternator and starter were fine. The autoparts person mention when a battery is changed, if they do not hook up some sort of memory device (to the same place the code reader is hooked) the PCM can be thrown out of whack and show the p1633 code.
This was the first time I heard this, but made sense since the battery had been disconnected once by me and changed twice by Sam's Club.
This brought me back to the dealer and the $129 charge.
My last option is to go under the hood and disconnect and clean the PCM connections and also, because of the weird brake lame thing, swap out all those bulbs.
I know this is long, but hope it makes some sense.
Any help or advice is appreciated.
A sincere thanks,
Mike
 
You need to look close at the battery cables. Are they swollen? which would indicate corrosion inside. The ground cable to the chassis, is it clean? The ground cable from the chassis to the engine block, is it clean? The positive cable to the starter, you will find hot lead there at starter to the rest of car, is it tight and clean? Dont mess with PCM connections yet, they rarely give problems.
 
All the connections look okay.... I will check the positive cable to the starter..only one I did not know about.
The other thing is when the code first popped up, P1633, I found out by buying one of the code readers from Costco. I cleared the code. It took a few days to come back, now comes on shortly after starting the car. Could this be from disconnecting the battery? In other words a totally different cause for triggering the light.
Which leads to my question.
When I change the battery or disconnect it....do I need to worry about those devices that keep the memory or you plug in when you change the battery?
I was told...since the battery was recently changed without hooking up one of these devices...the code is now permanent and needs to be reprogrammed by the dealer.
The car runs perfectly fine.

Thank you for taking the time to reply.
 
Do not worry about disconnecting the battery, You did not hurt a thing. It does NOT have to be reprogrammed by the dealer. Could you imagine if that were true, everyone with a dead battery would have had to reprogram theres. The light coming on after starting sounds like voltage is going low when cranking engine. At the starter where the cables come in check those connections. My lincoln cranks very fast and quick, does your crank slowly? A bad starter can draw alot of amps, but it would crank slowly as a side effect.
 
I noticed some green/whitish residue just above where the red wire come on the starter when I took a quick look this morning.
I have not had a chance to look real close and I am not sure exactly how to take the wire off.

What I noticed this morning, when the car had been sitting for over a day, I did have to crank/grind a bit more than usual, holding the key in the far position until the engine "fire up. (This is what happened months ago on the extremely cold day we had here in Chicago...sub zero temps only more so. When that happened, the lights were really, really dimming when I finally got it started.)

Several hours later today on the way home from work, it started right up, no cranking. The dashboard lights come on, several seconds later they all go off, and then about 10 seconds after, the check engine light rears its ugly head.
I will take a good look at the red wire on the started when the rain stops here.
Also, if a fuse were bad, wouldn't something just stop working? Someone suggested a loose fuse connection under the black fuse box inside the engine?
Thanks again,
Mike
 
My starter at the connection has a red cap over it. A nut holds the positive cable on. make sure to disconnect the negative battery cable before working or you might have sparks flying. You could have a bad starter, there easy to take off and have checked. These are a gear reduction starters in continentals, which means they dont draw alot of amps like older cars do. I changed my power steering pump last weekend and to prime the new pump ford says to disable fuel pump and crank engine for 20 to 30 seconds. I did so, and my lights barley dimmed.Let us know how it goes.
 
Hi Randy.
I found the red cap. I unscrewed the nut and took off the red cable and cleaned it really well. There were two other smaller wires which were difficult to get at and I did not touch them at this point.
I reconnected everything. I started the car and after about 10 seconds, the Check Engine Light came back on.
Will it take awhile to reset since I disconnected the battery? Or do I need to disconnect the battery for more than 30 minutes to clear the code?
The other thing is, I maybe because I was never paying attention before, there is a motor/pump/ or some type of compressor which seems to hum/rumble right after I start the car. It even goes off if I turn the key, but do not crank the engine. COuld this have something to do with the A/C or Air suspension? Just wondering. Again, I do not know if this is diagnostic of anything, but after I start the car when it has been sitting a day or so, the light comes on with all the other dash lights when the car is started. It goes off like normal, but then comes on after about 10 seconds. If I take a short trip, or shut off the engine right away and restart, the light never goes off after the initial ignition check.
Again...the car runs fine.
I have not gotten a chance to get to the matter until today, so It has been a week or so since my last post. No issues at all with the car such as starting or driving.
Occasionally when I do start it, It does take a split second longer, but no more than usually.
Wondering what my next step may be.
Thank you so much for your help.
Mike
(by the way. I invested 30 in a digital voltage meter. Is there any simple tests I could do which may help?)
 
The hum or rumble you are hearing is for the air suspension. Its the compressor, mine makes the same noise until it gets at the right ride height. I am stumped for now with your problem code P1633 . But we wont give up yet. I have good resource of Ford shop manuals and Mitchell on demand5. I will look deeper for you.
 
OK did a little more research on P1633 code. According to ford 1633 is set when voltage drops below 10.5 volts. Check all connections, starter,alternator,grounds,battery,and PCM. I did not see where to specifically check voltage at. I would start at battery then go from there to every hot lead you can find with your volt meter. If all checks out the last thing to condemm is the computer. Hook up voltmeter at battery and start the engine. What does the voltage drop to?? Some volt meters are hard to read like this because its going to happen faster than your eye might see things. Let us know.
 
Thanks Randy...
I just got a new Voltmeter, but must admit I have only limited knowledge on how to use it.
Do I simply touch the positive to the positive battery terminal and the negative battery terminal and have someone start the car?
And is the pcm located under the wiper directly in front of the driver or in the center of the firewall?
Several sources said to clean the PCM first.
I wonder..Autozone ran 3 tests on my car.
The battery voltage read 12.50, measured 870 CCA.
The Charging system tests read, "No Problems" no load:13.67 V and loaded 13.52V.
Now on the starter test. It says at the top, "Cranking normal", but if you look at the graph, the voltage starts at 11.26V, then right away drops below 9.00V on the graph., then at about a 45 degree incline goes back up to Just above 12V. Then takes another small dip just below 10.00V.
Could these dips in the starter test be the problem?
Again, I do not know my way around the voltmeter.
I will try to school myself on it.
An also, it someone could let me know how to get at the PCM, I can find it and check for corrosion etc...
After that...it may just be a trip to the dealer...
Thanks Randy!
 
Some info for you. The charging system is controlled by the regulator internal to the alternator and nothing else. If the charging system is bad, you will get a red battery light on the dash. This has nothing to do with the engine light or the engine computer (EEC).

I did a search on google and found on the mustang forum that a blown fuse was cause of P1633:

P1633 - Keep Alive Power Voltage Too Low Indicates that the Keep Alive Power (KAPWR) circuit has experienced a power interrupt.
Possible causes:
Open KAPWR circuit
Damaged PCM
Intermittent KAPWR Circuit
KAPWR is supplies from fuse 21 5 amp in the Central junction box (interior fuse panel). It is hot at all times.
 
Thanks for the post bradyelich.
I already checked the fuses they were fine. I replaced them anyway: on the panel inside the car I replaced, fuse 2 10A & 11 10A. They were the ones listed in the Owners Manual to be related to the PCM. I do not know if this is the same as the KAPWR you mentioned above.
Inside the engine I replaced small fuse #1, 30A and large 30A fuse #7.
The only thing I did not change was the PCM diode or the PCM Power Relay 7 (Small Black Box in the negine fuse box).
Cleaning the PCM connections were also mentioned except I have no idea were exactly the PCM is.
This all started with a real, real tough start months back where I must have really drained down the battery while cranking. The first time the light went on. I was able to disconnect the battery or clear the code with a scanner and it would days a few days to go back on. Where I am at right now is car starts fine. All dash lights go on with starting of ignition and then go off. Then after about 10-15 seconds the Check Engine Light goes on.
So far no starting or engine running issues I can sense.
The only thing I have of any consequence is the starter test showing the voltage drop below 9v. I do not know if that is diagnostic of a bad starter or voltage draw somewhere else in the car.
 
Ok....this if freaking weird!
I went out yesterday and disconnected the battery for over 2 hours. I cleaned off all the connections on the starter and battery again.
Reconnected after the 2 hours ...10 seconds after starting the check engine light went on.

Ok this is where it gets strange...today I decided to try out my new digital voltmeter.
I first checked the battery voltage with the car off. 12.54V.
I then read you can test to see if there is a unusual draw on your system. I disconnected the negative battery cable and set the meter to measure milliamps.
I connected one end to the negative post of the battery, the other to the negative cable.
The reading was 15mA (actually read 1.5mA but I was not sure on the decimal places.). No unusual draw was my amateur conclusion. I reconnected the cable.
I then opened the inside the engine fuse box.
I took out the PCM Diode to to the same amp test. One lead on each side. I got a reading of zero, so I was not sure I was doing it correctly or this was even a valid test.
I also took out fuses number 1 and 7 and did the same test for amps, the meter read zero so I was not sure it I did it right either. I also tried setting the meter to voltage and got zero. I also remover the PCM PWR Relay (black box) and checked it again for corrosion.
Nothing...so I put the relay back.
I then went inside the car and removed fuse number 2, 10A for the DLC and PCM.
Again, I had read these needed constant voltage. I set the meter and placed the red probe inside one end of the fuse and got a minimal voltage reading. I put fuse number 2 back.
I also did the same for fuse 11, a 10A fuse for Ignition Coils, PCM Relay and The Anti theft system. I took it out. Place the red probe on one side, and got a minimal voltage reading.
I was frustrated because I was not sure if what I was doing was correct (from memory).
I still had the car door open at that point as I untwisted myself from the inside fuse panel.
I started the car to make sure I had connected everything....
NO CHECK ENGINE LIGHT! Yes...I let the car run about 2 minutes and the light did not come on.
I restarted with the door open again....no light.
I then closed the door (maybe there is some weird electrical thing with the door) and started...no check engine light after a few minutes!
This leads me to my question and possible conclusions.
I somehow reconnected the negative battery cable to make better contact.
Pulling the relay and fuses out and placing them back somehow made a better connection somewhere.
Now the light may come on after I drive for awhile as it did weeks ago, but somehow pulling out these fuses and putting them back did something...my question is what exactly?
Any comments, thoughts, suggestions (and even prayers) at this point would be very helpful!

***Well, 30 minutes after typing the above, I left for work. Started up the car and..yep within 10 seconds the Check Engine Light was on. Totally confused now.
 
The PCM is under the dash on the floor behind the ashtray/cupholders in my 1997. The EEC is under the hood on the firewall. Maybe the new sound system is getting power from the PCM power wire?

Even if a battery test good, it may not be good, trust me I lived it. Your battery is holding only 12.54 volts. Should be more like 13. Your battery can only give 9 volts during cranking - not good. How old is the battery? Replace it if it is more than 4 years old. Ever take the caps off and add water?

The max draw with key off should be no more than 50 milli amps in the book. I think my car is higher like 500 milli amps.
 
Turned out to be a bad wire behind the driver's side wheel well. No sure which one. But fixed the issue.
 
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