should I replace ECM in 95 Buick Lesabre

Hi,
I have a 95 Buick Lesabre. It occasionally stalls. It will run bad/die for a few minutes then be fine for a few days. No codes show up and my mechanice couldn't get it to stall. He did say the cooling
fans were kicking in even when the engine was cool. He believes the ECM is bad. Also the outside temperature screen flashes when I start the car.
My mechanic said I would need to bring it to the dealer to replace the computer, because they would have to flash a chip in it.
Can I replace this myself? Autozone has the computer for $99. From what I have read on the internet, you can take the prom out of the old computer and put it in the new one. Is that the case?
Thanks chad
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snipped-for-privacy@chadphillips.org wrote:

You are correct. Your mech is wrong. Now, whether you need a ecu or not, I don't know.
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snipped-for-privacy@chadphillips.org wrote:

well if the comp is bad I doubt changing the PROM will fix anything. Computers rarely go bad slowly like that. If anything perhaps there is a bad connector somewhere. This sounds very much like the last person posting about the '95 Park Avenue below. Fuel Pump or EGR.
You could have a bad temp sensor somewhere, but the outside air temp sensor is always different from the one the engine uses to control the fans.
Also I dont know what this is about 'flashing' a chip. That should not be required.
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Thank you,


CL Gilbert
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snipped-for-privacy@chadphillips.org wrote:

I have a 95 Olds 88 that did have a bad ECM computer. Similar symptoms - intermittent stall/stumble for the first couple of miles driven, and then fine for the rest of the day. No codes set. My mechanic spent a lot of time trying to nail the exact problem and ended up determining it was the engine computer under the dash.
Then again, it could be a bad electrical ground, connection to the computer, ignition, fuel system problem, crankshaft sensor, etc.
I didn't do the work on my car, but regarding the PROM chip, I believe you do take it out of the old computer, and put it in the new one. Be careful handing it, since it is static sensitive. Don't touch any of the electrical contacts on it while swapping it.
Hope this helps. Bob.
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Bob wrote:

if there is a PROM in the new computer I would not swap it with the old one. Also I find it hard to believe the new one would come without a PROM.
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CL Gilbert
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CL (dnoyeB) Gilbert wrote:

GM ecu's do not come with proms. They must be removed from the old ecu and plugged into the new one. While it is possible to buy the entire unit new from a dealer, it is not necessary and will cost 5 to 10 times the cost of a promless rebuilt. A brand new one with a new prom will have to be flashed. Again, a few more hundred unnecessary dollars spent. A new ecu and flash from a dealer and it's a bit over $1000.
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Paul wrote:

I am at a loss as to why a new part needs to be 'flashed.' When suppliers deliver modules they are ready to be installed. GM wouldn't accept anything else. There is no reason for a flash. If the dealership ever told me they needed to 'flash' a brand new module they would be in for a fight.
This does happen on occasion when an update to the module is available. And in-stock parts have not been updated. But they should do this for free as its their own part.
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