Catastrophic Electrical Issues [2015 Q5 2.0T]
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Catastrophic Electrical Issues [2015 Q5 2.0T]
Long time Audi owner, in fact, I've only ever owned Audis until my most recent XC90 purchase. Where do I begin with my woes on this Q5:
1. Timing chain conked around 57k miles, had to change it. Fine!
2. Around 70k miles start drinking oil. Was ok in the beginning but then had to add a quart every 200 miles or less. What's more, had to change plugs every 2 months because of the crud. Then got into crazy misfiring issues and I almost put her to rest. Was exploring an engine rebuilt when I found someone who promised that replacing a passthrough PCV value with catch can setup would mitigate the issues. AND IT DID! I also added a new battery and new R8 coils. Now I'm back to topping off oil every 300-400 miles, and engine runs beautifully. Ok! (reach out if you need details on this job)
3. Alas, I hit a nagging electrical issue where something would drain my battery over several days. I would need to jump it to use it and that's what I'd do. I imagine somewhere along the way, things got worse. Here are all the symptoms:
a. System Lights Fault error
b. Random Parking Brake Failure error
c. Tire Pressure System Malfunction
d. Rear backup camera stopped showing up on the MMI
e. Rear tail and brake lights stopped working
I found that the rear right side hatch illumination light would sporadically stay on when the car was turned off, so I started there. I replaced the latch switch. This aligned with the symptoms - i.e., if the lift gate closure isn't being detected, it's going to assume the lift gate is open and keep all the things on/off depending on that state. Turned out not to be the issue. Then, CATASTROPHIC FAILURE:
1. I was doing my usual dropoff and had all the warnings happen one by one while driving.
2. AC shut off
3. All gauges shot off. Literally everything electrical shut off.
4. I was like ok...this is new. So I get there and turn off the car. I could not turn on the car from this point. The engine would turn, but would not stay on for more than a second. My hypothesis, the ignition system was taken down as part of the electrical issue.
5. I get it towed to the dealer
-- Dealer --
1. I agree to the $350 diagnostic fee for them to start looking into the issue
2. They call me saying it's the battery, and it was measuring 4V and it's $500 bucks to replace and should do the trick. I was like no, it's a brand new battery, try charging it. They were adament that the battery was no good because it was reading 4V. I was like ok, I'll return it to those bastards - thanks dealer!
3. Battery turns out to be A Ok. Charged it back and rubbed it in the dealer's face, who confesses that we have to suggest a new battery when this type of situation happens (I heard "ok you called our bluff")
4. Next I told them about the light staying on, and they said maybe it's the latch actuator itself and the connector to it. They also said moisture was detected possibly due to blocked drain lines from sunroof. Quoted me $1600 and $1800 respectively.
5. Miraculously, they had the car running when I got there.
6. On the drive back, all the symptoms returned (video attached). I call the dealer and he's real tight lipped. Finally he mentioned something around the 5F module perhaps could be faulty.
7. I'm back at square one - $350 poorer.
Any ideas folks? I can't believe this lemon I have at < 100k miles.
1. Timing chain conked around 57k miles, had to change it. Fine!
2. Around 70k miles start drinking oil. Was ok in the beginning but then had to add a quart every 200 miles or less. What's more, had to change plugs every 2 months because of the crud. Then got into crazy misfiring issues and I almost put her to rest. Was exploring an engine rebuilt when I found someone who promised that replacing a passthrough PCV value with catch can setup would mitigate the issues. AND IT DID! I also added a new battery and new R8 coils. Now I'm back to topping off oil every 300-400 miles, and engine runs beautifully. Ok! (reach out if you need details on this job)
3. Alas, I hit a nagging electrical issue where something would drain my battery over several days. I would need to jump it to use it and that's what I'd do. I imagine somewhere along the way, things got worse. Here are all the symptoms:
a. System Lights Fault error
b. Random Parking Brake Failure error
c. Tire Pressure System Malfunction
d. Rear backup camera stopped showing up on the MMI
e. Rear tail and brake lights stopped working
I found that the rear right side hatch illumination light would sporadically stay on when the car was turned off, so I started there. I replaced the latch switch. This aligned with the symptoms - i.e., if the lift gate closure isn't being detected, it's going to assume the lift gate is open and keep all the things on/off depending on that state. Turned out not to be the issue. Then, CATASTROPHIC FAILURE:
1. I was doing my usual dropoff and had all the warnings happen one by one while driving.
2. AC shut off
3. All gauges shot off. Literally everything electrical shut off.
4. I was like ok...this is new. So I get there and turn off the car. I could not turn on the car from this point. The engine would turn, but would not stay on for more than a second. My hypothesis, the ignition system was taken down as part of the electrical issue.
5. I get it towed to the dealer
-- Dealer --
1. I agree to the $350 diagnostic fee for them to start looking into the issue
2. They call me saying it's the battery, and it was measuring 4V and it's $500 bucks to replace and should do the trick. I was like no, it's a brand new battery, try charging it. They were adament that the battery was no good because it was reading 4V. I was like ok, I'll return it to those bastards - thanks dealer!
3. Battery turns out to be A Ok. Charged it back and rubbed it in the dealer's face, who confesses that we have to suggest a new battery when this type of situation happens (I heard "ok you called our bluff")
4. Next I told them about the light staying on, and they said maybe it's the latch actuator itself and the connector to it. They also said moisture was detected possibly due to blocked drain lines from sunroof. Quoted me $1600 and $1800 respectively.
5. Miraculously, they had the car running when I got there.
6. On the drive back, all the symptoms returned (video attached). I call the dealer and he's real tight lipped. Finally he mentioned something around the 5F module perhaps could be faulty.
7. I'm back at square one - $350 poorer.
Any ideas folks? I can't believe this lemon I have at < 100k miles.
AudiWorld Super User
Joined: Dec 2001
Posts: 13,996
Likes: 3,376
From: Georgia
Yeah, you won't get anywhere substantial with a generic OBD-II handheld. You have multiple issues, with no good foundation to start working any of them, because you don't have a good scan tool in hand for the vehicle you own. https://store.ross-tech.com/shop/vchv2_ent/
AudiWorld Super User
Joined: Dec 2001
Posts: 13,996
Likes: 3,376
From: Georgia
Really, 20 pages of codes? And they are randomly listed, not grouped by anything intelligible. And the second half has half the page fading out. This wasn't a flood vehicle, was it? It's like literally everything in the vehicle is broken.
Really, go buy VCDS so you can scan yourself, and clear codes and see what comes after making changes, etc. VCDS is half the cost of what you paid for that one time diag. If you don't have a Windows laptop to run VCDS on, then at least get OBDeleven (which sucks compared to VCDS for troubleshooting, but it's all you got if all you have are mobile devices).
Comfort CAN-bus in 1-wire mode (Electrical error in circuit), that's not a good thing. You need to go through the vehicle and make sure everything is dry, pull every connector, make sure it doesn't appear to have any wetness or corrosion, etc. The 5F infotainment unit, like the 56 radio and 47 sound system if you have it, are all MOST ring connected. If any of the devices on the ring fail due to no power, the whole ring goes down. You need to make sure every fuse is showing 12v, except the black columns on the ends of the dash, which are term 15. They should have 12v when ignition is on. (actually, brown fuses 1 through 4 on the driver's end of the dash are likely only powered with ignition or engine turning, as well).
Problem is if you fix anything, clear anything up, you can't clear codes and see what comes back. You have no tool to interact with the vehicle. At this point, everything is up in the air until you can confirm clean power and communications wiring throughout the vehicle. It could be as simple as a bad ground somewhere. A lot of the systems consolidate their grounds to a number of specific chassis points. But the scan log from ODIS is so disorganized, it's not worth my time to sort it out. Sorry.
Really, go buy VCDS so you can scan yourself, and clear codes and see what comes after making changes, etc. VCDS is half the cost of what you paid for that one time diag. If you don't have a Windows laptop to run VCDS on, then at least get OBDeleven (which sucks compared to VCDS for troubleshooting, but it's all you got if all you have are mobile devices).
Comfort CAN-bus in 1-wire mode (Electrical error in circuit), that's not a good thing. You need to go through the vehicle and make sure everything is dry, pull every connector, make sure it doesn't appear to have any wetness or corrosion, etc. The 5F infotainment unit, like the 56 radio and 47 sound system if you have it, are all MOST ring connected. If any of the devices on the ring fail due to no power, the whole ring goes down. You need to make sure every fuse is showing 12v, except the black columns on the ends of the dash, which are term 15. They should have 12v when ignition is on. (actually, brown fuses 1 through 4 on the driver's end of the dash are likely only powered with ignition or engine turning, as well).
Problem is if you fix anything, clear anything up, you can't clear codes and see what comes back. You have no tool to interact with the vehicle. At this point, everything is up in the air until you can confirm clean power and communications wiring throughout the vehicle. It could be as simple as a bad ground somewhere. A lot of the systems consolidate their grounds to a number of specific chassis points. But the scan log from ODIS is so disorganized, it's not worth my time to sort it out. Sorry.
Thread Starter
AudiWorld Junior Member
Joined: Oct 2002
Posts: 45
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I'm determined. I think I can get a windows laptop and the software. Will report back after that.
Meanwhile, here is the dealer diagnosis: https://api.mykaarma.com/video-walka...mage_and_video
After 20 pages of codes, they honed in on this one (since that was my observation - i.e., the trunk light doesn't go off when tailgate is closed). Guess they ignored all the 20 pages of other symptoms. Would really have loved it if they looked through those and told me you have a bigger problem.
Heck, if doctors don't treat humans that way, why should dealers diagnose cars that way.
Meanwhile, here is the dealer diagnosis: https://api.mykaarma.com/video-walka...mage_and_video
After 20 pages of codes, they honed in on this one (since that was my observation - i.e., the trunk light doesn't go off when tailgate is closed). Guess they ignored all the 20 pages of other symptoms. Would really have loved it if they looked through those and told me you have a bigger problem.
Heck, if doctors don't treat humans that way, why should dealers diagnose cars that way.
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AudiWorld Super User
Joined: Dec 2001
Posts: 13,996
Likes: 3,376
From: Georgia
So looks like they ran two different reports into the same PDF for whatever reason. The 20 pages appears to be the initial scan. Then the first 2 pages are a different scan, 55 minutes later. We're to assume they did something in that time to deal with the errors. So once we reorganize the information on the two page report, we get:
Not sure what to make of the J794 error since we have no freeze frame context. Probably just ignore it.
The J525 errors, blown rear door woofers, ok, nothing cryptic there.
J770 cannot be calibrated, something you'd have to look into if you like that little light in the side mirrors.
The rest, for the J623 ECM, J533 Gateway, and J393 BCM2 are the more concerning codes.
P2015, if you had the plastic intake manifold, that would be expected. That you have the metal intake manifold, you'll just have to sort through and see what's happening. You'd want to look at the load flaps actual and load flaps specified measuring values and see what's going on. P2015 means "I told it to move from low angle to high angle but it didn't". Is it the flaps, the actuator, or the sensor, ...?
Term 30 open circuit. Curious why they couldn't fix that. Usually would just be a fuse. The term 30 supply direct to the ECM goes through fuse 4 in the ECM box. Is that fuse ok? Most of the 12v to the ECM comes through the J271 relay, but that's term 87, not term 30.
The J533 errors might be related. The J772 backup camera module is on the comfort CAN. But there's a lot of stuff on that branch of the "green" CAN bus. But single wire mode means one of the wires are trashed by a physical issue or errant module on the bus. You can see the B8 comfort CAN bus layout in my diagram at https://www.audiworld.com/forums/aud.../#post25931460 Unfortunately, all the rear modules are on the same position of the CAN disconnect jumper, so that won't help with isolation much. But as you see, there's wire and modules all over the car on that CAN bus wire pair. Tracking the issue down could be a chore.
Then the J393 errors. The rear light bulb. Does that issue sound reasonable? Is there a right rear tail/turn/brake bulb out? It's unclear from the DFCC if it's talking about the rear lid or the rear bumper.
And then the rear lid error. Your initial scan had errors for both sensors. Apparently they fixed the error for sensor 1, or it self fixed and they simply cleared codes. That's part of the importance to having your scan tool in hand if you're going to try and do anything with all this yourself. As for the sensor 2, open / short to B+. Ie, it's not seeing current flow when it expects it.
Ok, so G525 rear lid -closed- sensor 1 and G526 sensor 2. They are in the same "object", each is a simple switch connecting a J393 pin to ground.
pin 1 - yellow - to J393 32-pin gray pin 9
pin 2 - green - to J393 32-pin gray pin 10
pin 3 - ground
I don't know what the syntax is for the switches. Is rear lid open an open on the switch, or a closed on the switch? Since we don't know if yellow or green is the G525 vs G526, we don't know which one is "working signals" and which one is "not working signals". But I guess if one is stuck, then only the other will toggle state if you check voltage with the lid open and closed. So back probe pins 9 and 10 and measure voltage relative to the battery positive (I don't know if you'll need to unplug the gray 32 to get a proper reading, to isolate the test from whatever circuitry the J393 has on those pins). With the lid open and then closed, which wire measures 12v and which doesn't.
Apparently the parts catalog calls it "switch for luggage comp. light for rear lid", 4L0959121. It's under the shiny silver luggage floor rear end plate. Apparently it just prys out upward. Don't get too carried away or you'll rip the wires out of the 3-pin.
Code:
01 - Engine electronics (J623) 2968 / P201500 / lntake Manifold Runner Position Sensor/Switch Circuit Range/Performance (10101111 active/static) 17262 / U140A00 / Terminal 30 Open circuit (00101111 active/static) 19 - CAN Gateway (J533) 470 / 12 / Comfort CAN-bus in 1-wire mode (Electrical error in circuit static) 2873 / 4 / Rearview camera system control module (No signal/communication static) 3C - Lane change assistance (J769 / J770) 730117 / C1115F0 / Lane change assistance control module 2 (J770) - lane change assistance control module automatic calibration not possible (00001001 active/static) 46 - Comfort System Central Control Module (J393) 2915 / 10 / Rear lid -closed- sensor 2 (Open circuit/short circuit to B+ static) 2772 / 12 / Right brake lamp/turn signal/tail lamp bulb (Electrical error in circuit static) 47 - Sound System (J525) 2558 / 11 / Left rear mid-bass speaker (Open circuit lntermittent) 2559 / 11 / Right rear mid-bass speaker (Open circuit lntermittent) 5F - information electronics (J794) 3157 / 0 / Function restriction due to communication interruption ( static)
The J525 errors, blown rear door woofers, ok, nothing cryptic there.
J770 cannot be calibrated, something you'd have to look into if you like that little light in the side mirrors.
The rest, for the J623 ECM, J533 Gateway, and J393 BCM2 are the more concerning codes.
P2015, if you had the plastic intake manifold, that would be expected. That you have the metal intake manifold, you'll just have to sort through and see what's happening. You'd want to look at the load flaps actual and load flaps specified measuring values and see what's going on. P2015 means "I told it to move from low angle to high angle but it didn't". Is it the flaps, the actuator, or the sensor, ...?
Term 30 open circuit. Curious why they couldn't fix that. Usually would just be a fuse. The term 30 supply direct to the ECM goes through fuse 4 in the ECM box. Is that fuse ok? Most of the 12v to the ECM comes through the J271 relay, but that's term 87, not term 30.
The J533 errors might be related. The J772 backup camera module is on the comfort CAN. But there's a lot of stuff on that branch of the "green" CAN bus. But single wire mode means one of the wires are trashed by a physical issue or errant module on the bus. You can see the B8 comfort CAN bus layout in my diagram at https://www.audiworld.com/forums/aud.../#post25931460 Unfortunately, all the rear modules are on the same position of the CAN disconnect jumper, so that won't help with isolation much. But as you see, there's wire and modules all over the car on that CAN bus wire pair. Tracking the issue down could be a chore.
Then the J393 errors. The rear light bulb. Does that issue sound reasonable? Is there a right rear tail/turn/brake bulb out? It's unclear from the DFCC if it's talking about the rear lid or the rear bumper.
And then the rear lid error. Your initial scan had errors for both sensors. Apparently they fixed the error for sensor 1, or it self fixed and they simply cleared codes. That's part of the importance to having your scan tool in hand if you're going to try and do anything with all this yourself. As for the sensor 2, open / short to B+. Ie, it's not seeing current flow when it expects it.
Ok, so G525 rear lid -closed- sensor 1 and G526 sensor 2. They are in the same "object", each is a simple switch connecting a J393 pin to ground.
pin 1 - yellow - to J393 32-pin gray pin 9
pin 2 - green - to J393 32-pin gray pin 10
pin 3 - ground
I don't know what the syntax is for the switches. Is rear lid open an open on the switch, or a closed on the switch? Since we don't know if yellow or green is the G525 vs G526, we don't know which one is "working signals" and which one is "not working signals". But I guess if one is stuck, then only the other will toggle state if you check voltage with the lid open and closed. So back probe pins 9 and 10 and measure voltage relative to the battery positive (I don't know if you'll need to unplug the gray 32 to get a proper reading, to isolate the test from whatever circuitry the J393 has on those pins). With the lid open and then closed, which wire measures 12v and which doesn't.
Apparently the parts catalog calls it "switch for luggage comp. light for rear lid", 4L0959121. It's under the shiny silver luggage floor rear end plate. Apparently it just prys out upward. Don't get too carried away or you'll rip the wires out of the 3-pin.
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Thread Starter
AudiWorld Junior Member
Joined: Oct 2002
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Update: Turns out a rat has been chewing on my wiring. I found a couple of wires right next to the rear passenger fuse box frayed with exposed copper. Pulled it out of the wheel well and it was a hot mess with all the black harness taping mostly chewed away. Taped them up good and that's taken care of.
Next - I laid out 6 mouse traps all over the vehicle in the engine bay, wheelwells, inside, etc. No mouse yet. So safe to assume the nasty bugger has moved on to tastier wiring
Now - I need to address the issue originally pointed out by the dealer: https://api.mykaarma.com/video-walka...mage_and_video
Pretty sure it's the wiring and connector.
Do you know how I can order just that connector that goes into the latch? Figured I'd address the connector and then the latch.
Another solution is to just replace the entire harness there - as i suspect there is more going on. Would this part work?
https://www.blackgoldparts.com/produ...xTuoecDhJW1KSN
Thanks again for all your support!
Next - I laid out 6 mouse traps all over the vehicle in the engine bay, wheelwells, inside, etc. No mouse yet. So safe to assume the nasty bugger has moved on to tastier wiring
Now - I need to address the issue originally pointed out by the dealer: https://api.mykaarma.com/video-walka...mage_and_video
Pretty sure it's the wiring and connector.
Do you know how I can order just that connector that goes into the latch? Figured I'd address the connector and then the latch.
Another solution is to just replace the entire harness there - as i suspect there is more going on. Would this part work?
https://www.blackgoldparts.com/produ...xTuoecDhJW1KSN
Thanks again for all your support!
AudiWorld Super User
Joined: Dec 2001
Posts: 13,996
Likes: 3,376
From: Georgia
The connector housing is just plastic; that's not the issue. The issue will be with the wire terminals inside it. So depin the wires from the connector housing and inspect them. Are the crimps good? Are the terminals (the crimp pins) corroded? Ring out the wiring back to the J393 and see which if any seem problematic.
pin 1 - green/yellow - J393 gray 32-pin pin 4
pin 2 - green/violet - J393 gray 32-pin pin 8
pin 3 - brown - chassis ground
pin 4 - green/red - J393 black 17-pin pin 5
Not sure what value that harness is since it appears they cut it off from the main interior harness; there's no "separate tail gate harness" for the Q5. So you're missing the full run of the wires. It's probably one of the two wires on the 32-pin gray. But easier to run a wire direct and see if that's actually it, then figure out how to secure it through the rear lid arm, etc.
pin 1 - green/yellow - J393 gray 32-pin pin 4
pin 2 - green/violet - J393 gray 32-pin pin 8
pin 3 - brown - chassis ground
pin 4 - green/red - J393 black 17-pin pin 5
Not sure what value that harness is since it appears they cut it off from the main interior harness; there's no "separate tail gate harness" for the Q5. So you're missing the full run of the wires. It's probably one of the two wires on the 32-pin gray. But easier to run a wire direct and see if that's actually it, then figure out how to secure it through the rear lid arm, etc.