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Engine Computer Problems

26K views 7 replies 5 participants last post by  aerojon 
#1 ·
Hi all,

I have a 2004 Saab 93 2.0t Linear. It has just over 101k miles and so far it has been great. Just a few weeks back the car went into what I imagine is limp mode. Power was greatly reduced, but it was most noticeable at low speeds. I took it by a friend to have the code read and it showed up as P0601 which is an engine control module checksum error. So I did plenty of searching and found that replacing the module should fix the issue. A temporary solution was unplugging the battery which resulted in the car going back to normal for a bit.

I went and bought a used module from a local junk yard and sadly that didn't solve the problem. I took the used module to the dealer to have it programmed and immediately after driving I noticed a huge difference. The car seemed to lack power at certain speeds. The engine would idle very roughly when first turned on. I went back to the dealer immediately and they really weren't going to help since they didn't diagnose the problem. So I drove it for a bit, but it hasn't gotten better. I also noticed that gas mileage is much worse with this module. The SID would usually average 30mpg or more for highway driving, but now it is around 23mpg. A day or two later the check engine light comes back on and this time the code is P0300 which is for multiple/random misfires.

I looked into that code and found various issues that are related such as a vacuum hose that may be cracked or plugs or coils that need to be replaced. I looked at the hose where it commonly cracks near the dipstick and mine seems to be fine. I also looked at the spark plugs and they don't look bad. I haven't driven with the used module for many days because I feel as if it is doing more harm than good. I put the original module back in and the car drives fine for several days before going into limp mode again or dieing while driving.

I am currently looking for any advice available. With the original module the car drives just as I would expect it to. With the used one it drives much worse with reduced power. It seems that the P0601 code is very rare to get and most people that reported the issue didn't respond after they had it fixed. Also it seems many of them had it covered under emissions warranty which my car is not eligible for since that warranty is only 80k miles. Sorry for the long post, but I really have researched this quite a bit and it seems like the only option is to take it to the dealer and buy a new module if that is the solution. I really would appreciate any help. Thanks.
 
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#2 ·
Did you get the replacement ECU for Linear?
Note, that if it is from 2.0T version (Arc/Aero/Vector)
it has completely different map loaded at that might be the reason
why the car is performing differently.

You can use second hand ECU but it has to be properly divorced & married.

Talk to your dealer, I had my ECU replaced last year under
emissions system warranty for free. But I had o2 sensor problems because
of the ECU so it's a little different story.
 
#3 ·
Hi xp3. Thanks for replying.
I am not sure if the ECU was from a Linear. I read some posts online and some said that it shouldn't matter if you have a 2.0t or 2.0T, but I have doubts about that. When I spoke to the technician about the problem, he said it was fairly easy to program. He said he had to enter the VIN so the module gets mated and he had to add the module to the car computer. I asked him if he thought that the module needed to be cleared because it maybe has data from the old car on it and he didn't think it should need to be done. I am guessing that he did not divorce it from the previous one, assuming that needs to be done. I saw this post:
http://www.saablink.net/forum/car-problems-new-9-3-only/55935.htm

DrewP said that the car needs to be SPS coded and not just added to the car. Not sure if that is a step that may have been missed.
 
#4 ·
Silversaaby,

Got your message on TSL, will re-post here to clarify for future help. I have a similar post saying about the same as below on SAABNet somewhere, my user name is the same there.



Silversaaby said:
I saw your replies in this post:
ECM code P0601

I am having the same problem and it was not solved when I took it to the dealer as I had expected. I bought a used ECU and brought it to the dealer to program. The car is driving worse now than before. Do you know what the steps are for programming a used ECU for a different car? Does it need to be divorced from the donor? Also does it matter if my car is a 2.0t and the donor was 2.0T? I am not sure what model the donor was.

I created a post on SaabCentral detailing my troubles:
http://www.saabcentral.com/forums/sh...d.php?t=218864

I would really appreciate any help. Thanks for your time.




As said above, and as you're suspecting, YES, year and engine variant does matter if the ECM was not SPS'd when it was added to your car.

There are two different steps to adding a control module to the 9-3SS.

1) "ADDING" the module is what used to be called "Marrying" the module to the car in the older cars. We had to do this with TWICE (anti-theft) and Radio modules, and ECM's to code the anti-theft immobilization code to the module. All that happens when you 'ADD' the module to a new car is it sets the security codes to allow the car to 'talk' to the module.

Think of 'ADDing' as setting the password on your home computer.

2) SPS programming is General Motors lingo for flashing the software in the module. This is what happens when you either update a module to a new software version (revision to UEC that lowers the voltage to the headlamp bulbs to make them last longer is one example). New modules from the dealer often come blank and have to be SPS'd anyway.

Any module being replaced should technically be SPS'd when it's installed in another car. SPS programming ensures that the module is coded to the correct set of equipment on that specific car, and makes sure the most recent software is loaded.

Think of SPS-ing as updating your operating system.



***************


Now, technically all 4-cylinder 9-3SS cars use exactly the same ECM. The part numbers on the back of the ECM are the same for any '03-'09 4-cylinder car (and probably '10 and '11 too, but I haven't seen one to confirm) regardless of engine output, transmission, or other options.

But, there were lots of calibration changes made over the years. All MY03 cars in the U.S. for example came with Secondary Air Injection systems, MY04+ does not. 2.0T (big 'T' or 210hp) engines have higher flow rate fuel injectors than the 170hp cars.

Just ADDing the ECM to the car can cause all kinds of problems.

Whenever possible I try to always install a used ECM that came from the same configuration car I am installing it to, that is same engine output, same transmission, same model year.

I tried to install an '03 Linear ECM in an '04 Linear once, and even after SPS-ing twice, and re-ADDing and clearing the bus it kept throwing fault codes for the SAI system, because the '03 ECM was expecting to see the Secondary Air pump.

The car ran fine, but CEL came on and I ended up having to replace with a later ECM.

I also had to install an '05 Linear ECM in an '05 Arc, so wrong engine configuration. That one ran really rough and threw fuel trim codes before SPS-ing the ECM. After I SPS'd it, it loaded the correct engine configuration maps and the car ran fine.

Since your car idles rough, I imagine you installed the wrong engine configuration ECM, you will have to find out for sure though.

Since I've had hit-and-miss results with mixing and matching years and configurations, I recommend that you try to find an ECM that's from the same config car as yours, and ask the dealer to SPS and ADD the module, although from their standpoint (and mine when I can sell the job) it really should be replaced with a new one, since a used one could possibly be throwing the same P0601-"Internal memory fault" code as yours, since we are starting to see them go bad.

As may have been mentioned, it may not hurt to see if this is covered as part of the 10-year emissions-related-component warranty.




Hope this helps!
 
#7 ·
ADDing a used ECU

There are two different steps to adding a control module to the 9-3SS.

1) "ADDING" the module is what used to be called "Marrying" the module to the car in the older cars. We had to do this with TWICE (anti-theft) and Radio modules, and ECM's to code the anti-theft immobilization code to the module. All that happens when you 'ADD' the module to a new car is it sets the security codes to allow the car to 'talk' to the module.

Think of 'ADDing' as setting the password on your home computer.

2) SPS programming is General Motors lingo for flashing the software in the module. This is what happens when you either update a module to a new software version (revision to UEC that lowers the voltage to the headlamp bulbs to make them last longer is one example). New modules from the dealer often come blank and have to be SPS'd anyway.

Any module being replaced should technically be SPS'd when it's installed in another car. SPS programming ensures that the module is coded to the correct set of equipment on that specific car, and makes sure the most recent software is loaded.

Think of SPS-ing as updating your operating system..............................



...............Just ADDing the ECM to the car can cause all kinds of problems.

Whenever possible I try to always install a used ECM that came from the same configuration car I am installing it to, that is same engine output, same transmission, same model year.
My dealer recently diagnosed my CEL as due to a faulty T8 ECU. Said it is a hardware fault, so the unit must be replaced. I'm trying to avoid the "dealer route" as they are sure to charge an arm and a leg for the replacement.
Here in Singapore cars have a 10-year artificially restricted "lifespan", and mine has about 1 year and a bit to go. Don't want to pay in excess of $1500 just to get rid of the CEL. I also do not need any updated or improved engine maps, just one that will see my car through to its 10th anniversary.


Since I've had hit-and-miss results with mixing and matching years and configurations, I recommend that you try to find an ECM that's from the same config car as yours, and ask the dealer to SPS and ADD the module, although from their standpoint (and mine when I can sell the job) it really should be replaced with a new one, since a used one could possibly be throwing the same P0601-"Internal memory fault" code as yours, since we are starting to see them go bad.
Would things work OK if I obtained a used ECU of the same model, transmission, year and variant, and get an independent garage (they have a Tech2) to do just the ADDing portion of the process? So far I've only observed them using the Tech2 as a diagnostic tool, so I'm not sure if they can do any SPS programming. It sounds like the ADDing part is more straightforward and something they could probably manage.

Do I first need to "divorce" my current (faulty) ECU before "marrying" the replacement ECU? Could you provide a STEP-BY-STEP procedure for the Tech2 operation, in order to accomplish the ADDing portion.

Thanks in advance
 
#5 ·
So not much has changed with the car. I found that the ECU that I purchased came from a 2004 Arc. I also called up the dealer and spoke with the tech that worked on my car. He said that he only performed the ADD operation which corresponds to the behavior I am getting(car is running Arc software with Linear hardware). I am planning on going to the dealer tomorrow to have him do the SPS programming, but it sounds like that is not a guaranteed fix either.

As far as the emissions warranty goes, it sounds like that is 8 years/80k miles so I am not covered by that any longer since I am at 101k miles.

If the SPS programming doesn't work, I guess I will probably just buy the new part and have the dealer do the install since that is most likely to succeed. I feel like the dealer is kind of screwing me since they knew I brought in a used part, but didn't think to do the SPS programming. Also, I just happened to find a part that is from a Linear and MY04 so I am considering going that route also.

The link that DrewP mentioned from Saabnet is this:
http://www.saabnet.com/tsn/bb/9-3/index.html?bID=141271

Thanks DrewP for responding to my PMs. I really appreciate the help.
 
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