ECU Replacement

[Silenthalo]

I believe i may need to replace the ECU in my Cavalier, and i just had a couple of questions that perhaps someone could answer for me:

1 - I have a 99 Cavalier, but it has a 2001 engine. When i get the ECU should i get it for a 99, or a 2001?

2 - When i install it, should it just work automatically, or will i need to bring it somewhere to be "reprogramed" or something of that sort?

Any help on these couple things would be awesome.... thanks guys

[94VL]

If you buy a reman or new ECM it will need to be "flashed" with the programming needed for your VIN#.I would imagine you want the year of your chassis/VIN and not the engine year.
(94-up Cavalier/Sunfire ECMs have no PROM chips,the programming is stored in FLASH memory.This way the same ECM can be used for different applications,they just change the programming.Also,any recalls or updated programming can be done with no ECM removal,just a plug in reprogramming operation.)

[Silenthalo]

i was thinking of getting it reprogrammed, but i dont think that will help (but i may be wrong) The problem is a # of things including:

-Theft System light always on
-Oil Light always on
-Battery Light always on
-Coolant Light always on
-Temp Gauge no longer functions
-RPM Gauge no longer functions
-Gear lamp no longer lights to indicate current gear
-An last but most important, every now and then (seemingly more frequently) the car will turn over, start, then stall immediately. It will do this over and over and then start and run normally at random. It may take 2 tries, it may take 20.

All of the above problems happened overnight, with the exception of the starting problems, those only began to occur within the last few weeks.

[pitbull781]

I'm begining to have the theft system light problem but it was just starting and then stalling I would wait 5 min and then turn the key off and start again and it fired right up and ran fine. but the other night that failed and i disconnected the negative battery cable for 5 min and reconnected. Light went off and car started fine but then on the way home it came back on and has been on ever since. Car still starts and runs fine.

[Silenthalo]

Yeah mine completely decides on its own whether or not it wants to start... sometimes it starts the second time i try, sometimes it just wont at all.... in that case i usually call a friend to counteract the boredom im enduring while i wait for about 5-10 minutes, and then try again... it usually starts right away after that wait. Very annoyiong when your trying to leave a friends house at 1am, and your outside cranking over your car 30 times, waking up the entire neighborhood hehe.

Hopefully this ECU replacement will fix it... and speaking of which:

Has anyone else ever had this problem besides us two? And if so, did you find a fix for it?

[wafrederick]

To program the ecu,you need a GM program on a pentium 4 capadable computer and the tech 2(Gm's factory scan tool).The best thing about GM's ecus is they can be programed a lot of times.

[97cavy]

Originally Posted by Silenthalo

Has anyone else ever had this problem besides us two? And if so, did you find a fix for it?

Yes, I have. Mine was just the secondary ground wire under the battery. I know I sound like a broken record, but check it over. Save yourself some cash maybe.