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Intermittent Electrical Power Loss and Stalling


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My daughter's 1996 DeVille began having a new problem this weekend.

On Sunday, the car seemed fine for most of the day. Then, later in the day I tried to shift the car into reverse from park. The car didn't shift but sat there with the engine just revving when pressing the accelerator. Basically, it stayed in park. I shifted back to park and then to reverse again and this time the car shifted fine. That particular problem happened only that one time and not again since. :blink:

However, I drove the car to work on Monday and that morning it had a fairly difficult time cranking up. It was similar to having a nearly dead battery but the car did manage to start. I didn't think too much of this because it always started on the first try but also in a very sluggish sort of way. I'm pretty used to it acting that way now so again I didn't pay much attention to it.

Monday after I got off work the car started up the way it usually does... sluggish but successfully on the first try. My drive home from work is about 35 miles. During this drive the car started acting very strange. As I was driving along all of the lights on the dashboard, stereo, A/C, etc. would flicker. I noticed that almost everytime I applied the brakes there was always a quick flicker. As I got closer to home the flicker lasted just a bit longer where it was even more noticable. I also noticed that now the radio volume control wouldn't increase or lower the volume but the steering wheel level would. That was odd and perhaps unrelated but all of this happened during this single trip. Then, I pulled into my neighborhood and the car just died. :o I shifted to neutral and after a couple tries I was able to get the car to restart. I was just about home when that happened and made it the rest of the way.

The next morning, I tried to start the car and it was totally dead. No power to unlock the doors, no lights, nothing. I turned the key in the ignition and got nothing at all. No crank, no click, nothing at all. Now, a really strange thing is that I put my foot on the brake pedal and suddenly the lights all came on. I turned the key again and the car started up. The clock was at 12:00 like the battery had been disconnected or completely dead. :(

Since the car was running again I checked the codes. What I got was neither a surprise nor was it very helpful.

PC0603 --- Control Module Long Term Memory Reset

PC1520 --- PRDNL Input Problem

IP1552 --- Keep Alive Memory (KAM) Error

Does anyone have any ideas as to what I need to get fixed in order to resolve this problem?

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My Guesses: Clean the battery posts, check the battery to see if it needs to be replaced, and perhaps you will need a new PRNDL switch.


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I second Bruce's diagnosis. Check the cable and connections on the PRNDL module on the top of the transmission directly in front of the driver.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Thanks guys!

I haven't had a chance to really do anything on the car yet. However, I did find a problem that I was able to duplicate several times. The car will start most tries but after shutting it off, occasionally the power goes completely dead. No lights, at all. Turn the key and there is no power, no lights, no sound of a crank or anything. You can try again and again and nothing. When this happens, with the key in the "on" position the gear shift will move without pressing the brake pedal.

Okay, now if you tap the brake pedal... everything lights up and the car will start just fine. I was able to make this happen many times in a row.

Also, while the car is idling in park if I press the brake pedal there is a loud electrical sounding "click" and the interior lights do the quick flicker thing I had mentioned before. If I shift into gear, the "click" no longer happens when the brake is pressed. Shift back to park and you have the "click" sound again.

SO... do you think perhaps there is a problem with a switch related to engaging the brakes rather than the PRNDL switch?

Just a thought...

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