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Question about replacing PCM


kad3338

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I'm needing to replace the PCM in my '95 Deville 4.9. Found a used unit to try with same model # info. Do I need to swap the Mem-Cal chip from my old unit into the new one, or can I just keep the new one in since it's from the same model #? Thanks.

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I would use your origional mem-cal and prom if replacable...

I am wondering.....WHY are you replacing thie PCM, they are rather long lived robust items?

Ohh...they can puke out. They are robust, but they can cause intermitant problems. I have replaced a many in the field.

Tap test a suspect ECM. Car can even stall during that test. Bad ECM/PCM.

Reman ones are maybe $125. Used even cheaper..

The older ones are nice, because, yes, you can replace it with a used unit. All the new ones are locked in with the VIN # on the Class 2 network. Wont work.

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Reman ones are maybe $125. Used even cheaper..

The older ones are nice, because, yes, you can replace it with a used unit. All the new ones are locked in with the VIN # on the Class 2 network. Wont work.

Logan,

If my 2006 messed up.... could I get a used one and have the dealer put the correct VIN in it with a Tech2? After I wrote a check of course. :D Wonder how much a new one would be?

Hope it never acts up.. but was just wondering.

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I'm needing to replace the PCM in my '95 Deville 4.9. Found a used unit to try with same model # info. Do I need to swap the Mem-Cal chip from my old unit into the new one, or can I just keep the new one in since it's from the same model #? Thanks.

GM's factory Service Manual states either replace the PCM or EPROM, but not both. In other words, use the original EPROM. I recently replaced a PCM and used the original EPROM as recommended--no problem. You will likely have to do the "Idle Learn" procedure for the Throttle Position Sensor after replacing the PCM--Code P080 will set indicating TP Sensor idle learn procedure is not complete.

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I still worry about replacing a ECM ....many replaced for lack of troubleshooting.

PCM/VCM/ECM has a extended emission warranty I think @ 80K .... Plus what evert the program at time of sale was.

Kev, can you explain what you mean by replaced for lack of troubleshooting?

We have had many members replace their PCM due to intermittant driveability issues. You can buy them reconditioned and I think new from the dealer, gmotors or rockauto. I am not sure if you have the new one reprogrammed or if you swap the eprom.

We have also had members go to the scrap yard and pick up one with the correct part/serial number and get successful results. We have especially seen a high amount of PCM problems from the 92 4.9. Mike

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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