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Anybody ever use the so called plug & play pcm’s that are available? Are they really that easy to change out ? Fist time really messing with system but pulled PO603 code which is by what i can figure out is for keep alive memory ???? Faulty PCM ???? Any help would be greatly appreciated !!!

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Replace the PCM for code 603? Is there another issue too? I would not change the PCM for that. 

From the GM service manual. 

'If the battery has been disconnected for any reason DTC P0603 will set. The PCM keeps a running check on the memory; if memory changes it resets. An intermittent loss of power or ground to the PCM will cause a reset.'

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10 hours ago, Logan said:

Replace the PCM for code 603? Is there another issue too? I would not change the PCM for that. 

From the GM service manual. 

'If the battery has been disconnected for any reason DTC P0603 will set. The PCM keeps a running check on the memory; if memory changes it resets. An intermittent loss of power or ground to the PCM will cause a reset.'

I had issues with it start, sounded like it was out of timing, changed the camshaft sensor and it fired right up and ran great. Drove it back and forth to work one day and next afternoon it’s right back to sounding like out of time again and throws the 603 code. Research I’ve done leads me to the pcm ?????

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2 hours ago, Jsblkram said:

I had issues with it start, sounded like it was out of timing, changed the camshaft sensor and it fired right up and ran great. Drove it back and forth to work one day and next afternoon it’s right back to sounding like out of time again and throws the 603 code. Research I’ve done leads me to the pcm ?????

The keep alive memory ????

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Edit: Any chance the car has a aftermarket radio....alarm system....or remote start?

 

From the GM service manual...

 

The PCM has a memory area where it stores certain data it needs to save when the key is turned OFF. This area is called Keep Alive Memory. This diagnostic test monitors the PCM's keep alive memory for a loss or unintended change of data. If such a condition occurs, DTC P0603 will set.

Conditions for Running the DTC
Tested continuously.

Conditions for Setting the DTC
Keep alive memory checksum does not match previous checksum.

Action Taken When the DTC Sets
Clear all keep alive memory locations.

    •  The Malfunction Indicator Lamp (MIL) will not illuminate. 

    •  No message will be displayed. 

Conditions for Clearing the DTC
    •  A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test. 

    •  A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail. 

    •  Use a scan tool to clear DTCs. 

    •  Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Powertrain Control Module Description . 

Diagnostic Aids
If the battery has been disconnected for any reason DTC P0603 will set. The PCM keeps a running check on the memory; if memory changes it resets. An intermittent loss of power or ground to the PCM will cause a reset.

 

 

Sounds like the battery cables and grounds should be inspected before replacing the PCM. It could be a bad PCM.....but I cant remember one posted here for a 603 and goofy running at times. 

We certainly have seen Cadillacs posted here with battery cables and or ground(s) problems. Corrosion etc in the fuse block etc.. Edit:....And aftermarket radios....alarms....and remote start systems causing problems. 

 

 

99battery603.jpg

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42 minutes ago, Logan said:

From the GM service manual...

 

The PCM has a memory area where it stores certain data it needs to save when the key is turned OFF. This area is called Keep Alive Memory. This diagnostic test monitors the PCM's keep alive memory for a loss or unintended change of data. If such a condition occurs, DTC P0603 will set.

Conditions for Running the DTC
Tested continuously.

Conditions for Setting the DTC
Keep alive memory checksum does not match previous checksum.

Action Taken When the DTC Sets
Clear all keep alive memory locations.

    •  The Malfunction Indicator Lamp (MIL) will not illuminate. 

    •  No message will be displayed. 

Conditions for Clearing the DTC
    •  A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test. 

    •  A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail. 

    •  Use a scan tool to clear DTCs. 

    •  Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Powertrain Control Module Description . 

Diagnostic Aids
If the battery has been disconnected for any reason DTC P0603 will set. The PCM keeps a running check on the memory; if memory changes it resets. An intermittent loss of power or ground to the PCM will cause a reset.

 

 

Sounds like the battery cables and grounds should be inspected before replacing the PCM. It could be a bad PCM.....but I cant remember one posted here for a 603 and goofy running at times. 

We certainly have seen Cadillacs posted here with battery cables and or ground(s) problems. Corrosion etc in the fuse block etc..

 

 

99battery603.jpg

From what I’ve looked at the cables are good but have not looked into fuse block other than checking fuses. I will dig deeper tomorrow see what I can find. Will keep u posted on what I find. Thank u for ur time !!! This is the best place to find out anything about Caddy’s !!! Thank u !!!

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53 minutes ago, Jsblkram said:

From what I’ve looked at the cables are good but have not looked into fuse block other than checking fuses. I will dig deeper tomorrow see what I can find. Will keep u posted on what I find. Thank u for ur time !!! This is the best place to find out anything about Caddy’s !!! Thank u !!!

Yes it does have aftermarket stereo and small amp and subwoofer but was professionally installed. Been in car for couple years with no previous problems like this.

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42 minutes ago, Jsblkram said:

Yes it does have aftermarket stereo and small amp and subwoofer but was professionally installed. Been in car for couple years with no previous problems like this.

 

Certainly a clue.....plus it's been a couple of years...

Lots of problems with aftermarket radios...alarms....remotes....and remote starts. 

The wiring does ok.....for a 'couple of years'.....then can start falling apart and cause all kinds of electrical gremlins. Not saying that's whats going on.....but it needs to be considered if you do not see any obvious problems during your inspection. 

 

 

 

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15 minutes ago, Logan said:

 

Certainly a clue.....plus it's been a couple of years...

Lots of problems with aftermarket radios...alarms....remotes....and remote starts. 

The wiring does ok.....for a 'couple of years'.....then can start falling apart and cause all kinds of electrical gremlins. Not saying that's whats going on.....but it needs to be considered if you do not see any obvious problems during your inspection. 

 

 

 

My stereo guy has been installing for over 30 years and has one of the best shops. I am very confident in his work, but I will definitely check everything out. Something really havnt given much thought. I will post results that I find. Thank you !!!

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23 hours ago, Jsblkram said:

My stereo guy has been installing for over 30 years and has one of the best shops. I am very confident in his work, but I will definitely check everything out. Something really havnt given much thought. I will post results that I find. Thank you !!!

Thank you Logan. 
After checking all fuse blocks for corrosion, which I found none, started looking into wiring to stereo system. Found one loose wire, the remote wire from stereo to amp. Reattached with new ends and car fired right up. Runs like a top now. I knew it was all tied in with computer system but actually never thought about a bad connection on stereo system. Thanks again Logan !!!! This site is the best !!!!

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