Battery dies every night - Canbus? Electrical short? Help!!
Discussion
As a noob to this forum let me say thank you in advance for any help or thoughts that you might have on solving a gremlin(s) that is inhabiting my 2008 DB9.
The background: Last June I found my car dead in the garage. This is the first time it had ever happened. The battery was new less than 12 months earlier. Upon jump starting the car I had a litany of issues crop up including transmission failure and an inability to get above a limp mode. I used my OBDII and cleared out a half dozen codes. The next morning the car was dead again. I repeated the process and took it in to the newly minted AM dealer, Morrie's, here in Minneapolis (closest dealer used to be in Chicago). They put in a new battery and thought everything was fine. After paying my bill I put the car into gear and the transmission light came on again along with a couple of other faults typically related to having a dead battery.
Next Steps: The dealership began to trouble shoot the car using two theories. The first is that a Canbus was staying open, draining the battery which then triggers the faults. The second is that there is an electrical short somewhere. Over the last 9 months my DB9 has sat in the shop while they tested each canbus and then proceeded to overlay wiring over the original harness section by section. Each night the battery would discharge again. As of last week still no solution. They engaged their regional service manage, still no solution. I do love my DB9 and summer here in Minnesota is short. Any ideas? What if I just put in a battery switch to cut power every night when I am done using it. Might that solve the problem for the short run? It bugs me that the brain trust at the dealership has no idea how to fix this problem. At this point I don't know where else to turn. Thoughts?
The background: Last June I found my car dead in the garage. This is the first time it had ever happened. The battery was new less than 12 months earlier. Upon jump starting the car I had a litany of issues crop up including transmission failure and an inability to get above a limp mode. I used my OBDII and cleared out a half dozen codes. The next morning the car was dead again. I repeated the process and took it in to the newly minted AM dealer, Morrie's, here in Minneapolis (closest dealer used to be in Chicago). They put in a new battery and thought everything was fine. After paying my bill I put the car into gear and the transmission light came on again along with a couple of other faults typically related to having a dead battery.
Next Steps: The dealership began to trouble shoot the car using two theories. The first is that a Canbus was staying open, draining the battery which then triggers the faults. The second is that there is an electrical short somewhere. Over the last 9 months my DB9 has sat in the shop while they tested each canbus and then proceeded to overlay wiring over the original harness section by section. Each night the battery would discharge again. As of last week still no solution. They engaged their regional service manage, still no solution. I do love my DB9 and summer here in Minnesota is short. Any ideas? What if I just put in a battery switch to cut power every night when I am done using it. Might that solve the problem for the short run? It bugs me that the brain trust at the dealership has no idea how to fix this problem. At this point I don't know where else to turn. Thoughts?
I think it was on temp wise. The alternator wouldn't be the issue I don't believe. Putting in a fresh, fully charged battery and letting the car sit unused for a day or two still resulted in a dead battery. Somehow the battery is going flat very quickly, just sitting. I think that is why an open Canbus or short seemed to make sense.
I thought the accepted method for tracing battery drain was to measure current at idle using a multimeter and then - assuming it's excessive which appears to be the case here - start pulling fuses so that you can at least narrow down the circuit which is taking all the current.
Have they done that?
Have they done that?
I agree with 'davek' except for the 'idle' bit. Check the current with everything in the same state as when the car is parked.
IMO- if a fully charged battery is discharged over night, something must be drawing a LOT of power and getting hot. You might be able to locate the fault with a thermal camera.
IMO- if a fully charged battery is discharged over night, something must be drawing a LOT of power and getting hot. You might be able to locate the fault with a thermal camera.
agaton12 said:
I agree with 'davek' except for the 'idle' bit. Check the current with everything in the same state as when the car is parked.
IMO- if a fully charged battery is discharged over night, something must be drawing a LOT of power and getting hot. You might be able to locate the fault with a thermal camera.
'Idle' was probably a poor choice of words. I meant off / locked as it would be overnight.IMO- if a fully charged battery is discharged over night, something must be drawing a LOT of power and getting hot. You might be able to locate the fault with a thermal camera.
DB9inMN said:
I am looking for a second opinion. I am asking all of the learned members of this forum! lol. I doubt they have spent a huge amount of time working on it but 9 months seems more than a bit excessive. As far as pulling fuses, I believe that was done but I will double check
thanks
An issue on early DB9 was the door module [by Valeo]. Car would cycle unlock/lock repeatedly until battery flat.thanks
Done this job a number of times on various cars. (Though never AM, alas)
1) In line ammeter on the battery to measure current accurately (Down to 10ma) - see what it pulls. (Need to wait for 5 or 10 mins so it drops to minimum as things shut off.)
2) Pull all the fuses, 1 at a time to see if it makes a difference to the drain current. Disconnect the alternator if the fuses make no difference.
3) If nothing obvious, make sure any auxillary stuff is disconnected - phone, sat nav, after market radio etc etc. If none of the above, probably a canbus error - Proceed as follows.
4) Find a spot to look for can signal, put an oscilloscope on it, and look for signal.
5) Measure current and signal, see if the 2 are related, monitor over 24 hrs, and see if the canbus, either fails to shut off, or wakes up.
6) In the event of a can error, remove each of the can units, one by one, to see which one it is. As someone said, start at the most obvious or easiest to get to, and do each in turn.
This method will find your drain, but it's not cheap or easy, and involves a load of testing - maybe 30 days or more on test in a worse case scenario. (Ask me how I know).
Auto electrician here, so I speak from some position of understanding.
1) In line ammeter on the battery to measure current accurately (Down to 10ma) - see what it pulls. (Need to wait for 5 or 10 mins so it drops to minimum as things shut off.)
2) Pull all the fuses, 1 at a time to see if it makes a difference to the drain current. Disconnect the alternator if the fuses make no difference.
3) If nothing obvious, make sure any auxillary stuff is disconnected - phone, sat nav, after market radio etc etc. If none of the above, probably a canbus error - Proceed as follows.
4) Find a spot to look for can signal, put an oscilloscope on it, and look for signal.
5) Measure current and signal, see if the 2 are related, monitor over 24 hrs, and see if the canbus, either fails to shut off, or wakes up.
6) In the event of a can error, remove each of the can units, one by one, to see which one it is. As someone said, start at the most obvious or easiest to get to, and do each in turn.
This method will find your drain, but it's not cheap or easy, and involves a load of testing - maybe 30 days or more on test in a worse case scenario. (Ask me how I know).
Auto electrician here, so I speak from some position of understanding.
Here is the latest from the dealer's mechanic
This is Eric Lundquist the mechanic that has been diagnosing your vehicle. You are correct in your question that this is the correct way to determine a battery drain issue. What we have determined is that obviously you have an excessive drain issue on your battery, and what we determined was two things. First when going through the diagnosis was that the transmission is the cause of that main parasitic draw. With the transmission un plugged most of the draw goes away but we still had a small excessive draw beyond that. So the second issue we found was your serious/xm module also causing a drain beyond what aston martin said to be normal. So with these two things un plugged your battery issue is corrected.
The major issue that leaves us stuck and what we have been working to determine is why does the transmission control module drain the battery? What the problem appears to be is the transmission control module is not going to sleep when the car is shut off. So this seems to be causing a lot of issues with the vehicle, the transmission control module along with all the other modules on the car need to talk to each other to know what's going on at any given time. This is done through communication lines called CAN lines that all run through the vehicle electrical harness, and so sometimes when one of these modules is failing they will start to send messages to the other modules and they may not make sense to the other computers in the car. This is what I believe is happening to the transmission module, its sending garbled messages to the rest of the car and not receiving the message to shut down when the ignition is turned off.
So the things that we have been doing in the time the vehicle has been here to try to figure out why this is happening are along with communicating with aston is checking all the grounds on the car. This has been a lot of the process as this has been an issue with aston having poor grounds due to the vehicle being aluminum. We have found a couple ground in the process that did need fixing but they did not correct the issue so far. Also checking the CAN lines to make sure they are correctly intact allowing all the computers to talk to each other with out interruption. We have also tried re programming the transmission control module to see if it was corrupted software causing the issue which can happen when vehicle batteries go dead. This has also not corrected the concern of the transmission module not going to sleep. Also we fixed the shifting buttons on the dash as they were not sending correct signals to the car as they had a poor ground, we did this by running a new ground wire as this was a recommendation by aston. Once again this also did not correct the issue but it will solve further shifting issues in the future. So where we are at today is we believe the transmission control module which is integral to the internals of the transmission is the main failure. But this part is very expensive and not returnable, and I still don't have a solid answer is why the transmission does this or if replacing the transmission control module will for sure correct the issue as aston cannot give me much of an answer either.
This is Eric Lundquist the mechanic that has been diagnosing your vehicle. You are correct in your question that this is the correct way to determine a battery drain issue. What we have determined is that obviously you have an excessive drain issue on your battery, and what we determined was two things. First when going through the diagnosis was that the transmission is the cause of that main parasitic draw. With the transmission un plugged most of the draw goes away but we still had a small excessive draw beyond that. So the second issue we found was your serious/xm module also causing a drain beyond what aston martin said to be normal. So with these two things un plugged your battery issue is corrected.
The major issue that leaves us stuck and what we have been working to determine is why does the transmission control module drain the battery? What the problem appears to be is the transmission control module is not going to sleep when the car is shut off. So this seems to be causing a lot of issues with the vehicle, the transmission control module along with all the other modules on the car need to talk to each other to know what's going on at any given time. This is done through communication lines called CAN lines that all run through the vehicle electrical harness, and so sometimes when one of these modules is failing they will start to send messages to the other modules and they may not make sense to the other computers in the car. This is what I believe is happening to the transmission module, its sending garbled messages to the rest of the car and not receiving the message to shut down when the ignition is turned off.
So the things that we have been doing in the time the vehicle has been here to try to figure out why this is happening are along with communicating with aston is checking all the grounds on the car. This has been a lot of the process as this has been an issue with aston having poor grounds due to the vehicle being aluminum. We have found a couple ground in the process that did need fixing but they did not correct the issue so far. Also checking the CAN lines to make sure they are correctly intact allowing all the computers to talk to each other with out interruption. We have also tried re programming the transmission control module to see if it was corrupted software causing the issue which can happen when vehicle batteries go dead. This has also not corrected the concern of the transmission module not going to sleep. Also we fixed the shifting buttons on the dash as they were not sending correct signals to the car as they had a poor ground, we did this by running a new ground wire as this was a recommendation by aston. Once again this also did not correct the issue but it will solve further shifting issues in the future. So where we are at today is we believe the transmission control module which is integral to the internals of the transmission is the main failure. But this part is very expensive and not returnable, and I still don't have a solid answer is why the transmission does this or if replacing the transmission control module will for sure correct the issue as aston cannot give me much of an answer either.
I have been so sorry to read about the problems affecting your DB9, Jon and in particular, that the dealer has kept your car for such a long time. You should be enjoying your car, not having an appointed dealer trying for 9 months and still appearing not to know what is wrong.
The latest communication from your dealer which you have posted, describes such a complicated electronic system, that the 1969 Moon landing craft was probably far simpler. Then they conclude by indicating, that they seem to have no idea what to do next. A terrible situation for you.
Did you note though, that they also inferred that neither did Aston Martin know what to do. I don't think AML will like that comment, so perhaps you should try contacting Dr. Andy Palmer for help. He helped a PHer recently. Contact through Twitter was how it was done.
Neil1300r said:
Why can't the dealer swap the transmission module with another car in stock? Doesn't have to be a permanent swap, just long enough to prove the diagnosis. If it proves it then get them to order a new one.
DB9inMN said:
Here is the latest from the dealer's mechanic
the transmission control module which is integral to the internals of the transmission
the transmission control module which is integral to the internals of the transmission
Jon39 said:
I have been so sorry to read about the problems affecting your DB9, Jon and in particular, that the dealer has kept your car for such a long time. You should be enjoying your car, not having an appointed dealer trying for 9 months and still appearing not to know what is wrong.
The latest communication from your dealer which you have posted, describes such a complicated electronic system, that the 1969 Moon landing craft was probably far simpler. Then they conclude by indicating, that they seem to have no idea what to do next. A terrible situation for you.
Did you note though, that they also inferred that neither did Aston Martin know what to do. I don't think AML will like that comment, so perhaps you should try contacting Dr. Andy Palmer for help. He helped a PHer recently. Contact through Twitter was how it was done.
Thanks Jon, Great name by the way The latest communication from your dealer which you have posted, describes such a complicated electronic system, that the 1969 Moon landing craft was probably far simpler. Then they conclude by indicating, that they seem to have no idea what to do next. A terrible situation for you.
Did you note though, that they also inferred that neither did Aston Martin know what to do. I don't think AML will like that comment, so perhaps you should try contacting Dr. Andy Palmer for help. He helped a PHer recently. Contact through Twitter was how it was done.
If I knew how to get a hold of anyone who was worth a damn at AM I would. Unfortunately I don't tweet. They have said no one at AM seems to have a clue. If anyone knows anyone I can reach out to I would appreciate it. I am at the end of my trail. I did get the DB9 in my divorce now I think I should have stuck her with it I predict the dealer will not cut the CAN wires - they will insist the loom must be replaced if this is the case. The key to the repair is to make the wires the same length (especially if you are soldering a piece into it). The CAN chip is easily clever enough to cope with cutting and refixing a wire in my experience.
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