Hello everyone. I need some help.

I have a 2009 Lucerne with the 3.9L V-6. The problem started when I mistakenly drained the battery while I was in a store. When I came back out, I tried to crank the car. The starter spun, but was dragging badly due to the low battery. I tried it a second time and nothing happened: no starter motion, no clicking, even the dash lights went out while the key was in the "start" position. I made several attempts to jump it off, to no avail. I finally installed a new, charged battery. Nothing fixed the problem.

I did some research online and it seemed to be a problem with the ECM. The next day I located the starter and tried applying power directly to the solenoid. The starter turned the motor over just fine, but the motor would not crank. So, having eliminated starter issues, I ordered a new ECM programmed for the car. I installed the new ECM and turned on the key expecting to do a PASSlock III relearn. Instead I got the standard dash screen. I tried to start the car and had the exact same issue.

I got a wiring diagram for the ECM from the company that sold me the new one. I have verified what I can: all fuses are good; ground is making connection; I have power verified at the fuses leading to X1 pins 19 (ign volt) and 20 (battery volt); I have power verified at the powertrain relay, but have not been able to get the ECM to ground the coil. Despite having the wiring diagram, I do not have a pin-out of the connectors. Pin 73 was easy to figure out (that's how I verified ground; pin 73 on X2 is the ground), but I have no idea how the other pins have been numbered. The people who sent me the wiring diagram did not have access.

I have tried to get my local dealer to perform a diagnostic, but due to a medical disability that prevents me from wearing a face mask, they will not allow me access to the dealership. I'm already out a tow bill both ways over that one.

At this time, I have the old ECM back in.

New battery, new ECM, all inputs verified as best I can, no output whatsoever apparently... what is going on here?

 

JD, you are not going to like me at all, here's why !

We can get to the original problem up the road.

IF,,,,,,,,,,the company/place that sold you the replacement PCM did not have your VIN # there is no way they could program the replacement PCM.to your vehicle.
So,,,,,,,,,,,,,,taking things one at a time lets see the answer to that question first, did they get that info from you?

If the replacement PCM was not programmed correctly to your particular vehicle , it will never start
Then, if you installed an incorrectly programmed PCM and attempted to start the engine ,the system becomes confused and will no longer start with the original PCM.

We should be able to offer some guidance to get things straightened out, but it will take some patience and knowing what choices you have. What do you think?
By the way, if you haven't had the vehicle fixed yet, some vehicles need to be told the battery has been replaced . If not done another can of worms has been opened.
We should be able to offer some guidance to get things right.

 

Yes, they received the original VIN number from me when the ECM was ordered. I made certain that they had the correct number by repeating it twice and then having them read it back to me while I was looking at the number on the car. It's always possible someone made a typo (I really hope not), but they had the right number.

Thanks for pointing that out, though. Others might be tempted to try and just toss another ECM in there. As you say, that would cause more troubles than it would solve.

Doug

 

Lets hope we didn't create some addl problems getting involved with the ECM.

From the symptoms you described, I have some reservations as to whether the ECM was the problem,
Usually when a loss of power is the cause , loss of other functions become a problem also.

With a new fully charged battery and attempted jump start , both yielding no result would cause me to suspect internally corroded battery cables or poor connections where the cables are fastened to the engine. As you know , when insufficient voltage is available , the ECM cannot function. Low system voltage just causes everything to either malfunction or just shut down. Could this be the root cause of the problems?

 

Low voltage was definitely the root cause; I stated that in my first post. I ran the battery down by accident.

The U0100 code I get from the old ECM shows a new ECM was needed. If it isn't even responding after re-establishing voltage, it has to be replaced. I suspect that I was on the verge of having trouble with the fuse box anyway and the low voltage condition just caused it to finish corroding past the point of contact. Whether the corroded fuse box blew the old ECM or the old ECM drew too much power and increased the corrosion in the fuse box, I have no idea. Either way, both showed bad.

The new fuse box comes in today! Hopefully dogwood winter is on the way out and I can get the new fuse box installed this weekend. We'll see what happens from there; maybe this thread will help someone else with similar issues someday. Oh, to have a nice heated shop to work on a car in!

Doug

 

Doug,
Lets hope your diagnosis helps lead to good results.
There is a lot going on here and you may still require a certified locksmith or dealer tech with the right equip to get this squared away.

What does your anti-theft (security) light do when you turn the key on? Give it a few minutes to do it's checkout procedure.

 

The security light comes on with all the other lights in the lamp test, but then goes back off. However, the problem seems to have been resolved, although there are some confusing aspects... I'll put that in a general reply to the thread.

Doug

 

The new fusebox did the trick. Apologies to everyone for the delay, but dogwood winter kept me inside for a few days there.

A little strangeness: after I replaced the fusebox and hooked up the new ECM, I expected to have to go through the key relearn procedure. The security light came on and went right back off like it had been doing thoughout this whole ordeal. So, I suppose just to spite the car, I turned the key to start, and the thing cranked.

I still have the P0315 code, but the engine runs smoothly and there is a procedure to reteach it the crankshaft variability. I also still get the dash warnings over the Stabilitrac and ABS systems; I plan on going by an auto parts store I use tomorrow; they will clear codes for the entire car for free. If those codes persist, I'll have to dig into those systems, I suppose. In the meantime, I am having no traction issues and the brakes feel fine. The little test run I already gave it went perfect.

You guys are angels. Thank you so much for the assistance. When I joined to make this thread, I was completely lost. I believe that, were it not for you, I would still feel that way while looking at a paperweight with Buick logos on it. Words cannot express my full appreciation.

Doug

 

This is more like a job of a mechanic so call him them not a locksmith for that job.1