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Discussion Starter · #1 ·
Hi all! Hoping someone can shed some light on a couple of issues my A5 has developed (sport coupe, 2.7 TDi V6 on an ‘09 plate).
Few weeks back, after the heavy snow that swept the country, and after the car had been sat under it for a week or so unused I looked out the kitchen window and I noticed the DRL’s were on, even though the car was locked up and the lights are usually left on Auto on the switch. Went out and checked to make sure, and the switch was on Auto as normal, but the lights on warning sounded when I opened the door. Switched the switch to Off and the warning alarm stopped but I noticed that now the lights are always on when the ignition is on, coming home DRL function etc doesn’t work now, and the switch does nothing regardless of where it’s set 😂🤷🏻 main beams flash off the stalk as normal, and there is a ‘Malfunction- vehicle lights’ warning coming up on the dash.

Other issue, my wipers have completely stopped working. Stalk does nothing at all except washers, and headlight washers which are fine. The trip meter button works also. The motor isn’t seized as I can manually push the wiper arms through their full range. Service mode does nothing either…switch it on in the MMI and it cycles back to off after a couple of seconds and the wiper arm position doesn’t change. Not getting a wipers malfunction message or anything…just went from working fine to not at all without any warning whatsoever. Both the lights issue and the wipers malfunctioning seemed to occur pretty much simultaneously, so might have a common root cause maybe? 🤷🏻

I’ve googled extensively and the only thing I found that replicated both problems happening within days of each other, as mine did was in a VCDS support forum, which was apparently body control module related, would that be the one under the dash or the one in the boot? And would that module control power to both these circuits? I’ve done all the usual fuse checks etc and all test fine when belled out with a multimeter and visually look ok and free from corrosion. Similarly, I’ve checked the plug connectors on the light switch and the wiper motor and both look fine.

Lastly, on cold start the whole car shakes like a 1970’s tractor for about 15 seconds 😂 then it ticks over like the well made German car it’s meant to be 🤨😂 Normal on this engine or cause for concern? Runs perfectly well mannered after the initial tremors.
Any suggestions on any of that? I have VCDS Lite, but it won’t talk to my car because it’s CAN BUS, so I can’t pull any diagnostics up 🙄 normal cheap OBD reader says there are no generic codes stored to read.

All answers gratefully recieved…I’m at the end of my tether!
 

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Discussion Starter · #3 ·
Welcome. Are there any signs of water ingress? Under the dash drivers side or right rear behind the trim panel?
Hi John,
There’s definitely some water in the boot, both in the spare wheel well and the right hand cubby….the yellow foam is wet but not standing in water and all the fuses test out ok and module connectors look corrosion free and solid. I took out the two modules on the left side of the cubby to inspect them and both looked dry as far as I could tell. I’ve been trying to find out which circuits they control but not been able to pin down anything exact using google and the search function on here so I’m still in the dark.
Not had a chance to check behind the dash yet, but the footwell carpets are bone dry and no condensation on the inside glass so I imagine it’s dry
 

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Discussion Starter · #4 ·
Ordered a hex can cable from a Ross tech distributor, which should be here in a few days so that will hopefully point me in the right direction! Seems to have developed a parasitic draw on the battery now as well 🙄🤦🏻😂 can honestly say that this is probably the most problematic car I’ve owned…in the few months I’ve had it, it’s been nothing but hassle. Not what I expected for a just barely 100k motor tbh! Man it’s pretty though 😂🤷🏻
 

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You can put a fan or fan heater in the boot pointing into the cubby. That should get it dried out (obviously don't let it get too hot). And have a careful look to see if there are any water marks/residues on the various electrical components. It might give you a clue as to which module has got wet and where the leak came in from (assuming from above).
 

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check the electrical cable loom that is sat on the foam.. if it got wet then water will seep through the fabric loom tape into the cable joints. there are a few +ve crimped connections in the loom around there
 

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How is the condition of your car's battery? How old? Any signs that it is getting weak? When the battery gets weak especially if the car has been left out in the cold for quite sometime, the BCM starts shutting down non-essential functions just to conserve power enough to get the car to start. If you notice slow cranking when you try to start the car, this could mean one of two things: The battery was not properly charged up before parking it for quite sometime in the cold. Or, the battery is on its last legs and could not keep a charge like it used to.
 

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Discussion Starter · #9 ·
How is the condition of your car's battery? How old? Any signs that it is getting weak? When the battery gets weak especially if the car has been left out in the cold for quite sometime, the BCM starts shutting down non-essential functions just to conserve power enough to get the car to start. If you notice slow cranking when you try to start the car, this could mean one of two things: The battery was not properly charged up before parking it for quite sometime in the cold. Or, the battery is on its last legs and could not keep a charge like it used to.
the battery that was in the car was low so I charged I fully…was almost dead within a couple of days though. Fitted a new one, and that was also dead within a couple of days 😂 so I’m guessing there is a parasitic drain on one of the circuits. Gonna dry the boot out tomorrow now the weather is a bit better, then start poking around some of the wiring - found a thread on another forum about a surprisingly common issue with a crimped connection in the boot wiring loom that is water leak related….seems water gets into the crimp and corrodes the wires to the point that they put a high resistance on the circuit or snap altogether. Once I’ve got all that somewhat sorted out and traced and fixed the source of the water leak hopefully I’ll be at a point where VCDS will show up a problem 👌🏽
 

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the battery that was in the car was low so I charged I fully…was almost dead within a couple of days though. Fitted a new one, and that was also dead within a couple of days 😂 so I’m guessing there is a parasitic drain on one of the circuits. Gonna dry the boot out tomorrow now the weather is a bit better, then start poking around some of the wiring - found a thread on another forum about a surprisingly common issue with a crimped connection in the boot wiring loom that is water leak related….seems water gets into the crimp and corrodes the wires to the point that they put a high resistance on the circuit or snap altogether. Once I’ve got all that somewhat sorted out and traced and fixed the source of the water leak hopefully I’ll be at a point where VCDS will show up a problem 👌🏽
OK. This tells me that most likely your car's BCM shut off all non-essential electronics due to the dead or weak battery. When you replaced the old battery with a new one, the car won't recognize it as a new battery unless you re-code the system using VCDS or through an Audi dealer's VAG diagnostic system. Re-coding the system will tell the BCM that a new battery is installed so it will send power to everything in your car and adjust the charging rate for the fresh battery. The BCM adjusts charging rates based on the battery resistance as it gets older and weaker. So, it you were not able to code the new battery, the car's system will continue charging it as if the old battery is still installed. This will be bad for a fresh battery.
 

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Discussion Starter · #11 ·
OK. This tells me that most likely your car's BCM shut off all non-essential electronics due to the dead or weak battery. When you replaced the old battery with a new one, the car won't recognize it as a new battery unless you re-code the system using VCDS or through an Audi dealer's VAG diagnostic system. Re-coding the system will tell the BCM that a new battery is installed so it will send power to everything in your car and adjust the charging rate for the fresh battery. The BCM adjusts charging rates based on the battery resistance as it gets older and weaker. So, it you were not able to code the new battery, the car's system will continue charging it as if the old battery is still installed. This will be bad for a fresh battery.
That makes complete sense, but from my research so far my understanding is that as my car is pre facelift it shouldn’t need the battery specifically coded to the vehicle…it had a lead acid type battery fitted, which would back up that thesis but I’ll have my VCDS cable tomorrow so I’ll be able to confirm this one way or another 👍🏼
 

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That makes complete sense, but from my research so far my understanding is that as my car is pre facelift it shouldn’t need the battery specifically coded to the vehicle…it had a lead acid type battery fitted, which would back up that thesis but I’ll have my VCDS cable tomorrow so I’ll be able to confirm this one way or another 👍🏼
The battery in my B8.5 S5 is a lead acid type because it was not equipped with the Auto Start/Stop funcion which requires an AGM type deep cycle battery. Unless battery manufacturers come up with a smart battery that tells the car (digitally) its real battery state, any car with a BCM will have to be told if it receives a new battery.
 

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BCM & BEM are not the same thing. OP's B8 A5 will likely have a Battery Energy Management module -J367- as a sub-module to the CAN Gateway -J533-. It is attached to the negative post of the starter battery. When OP gets his Ross-Tech cable and runs an auto-scan, he'll find this reported under Address 19, e.g.:
Code:
Address 19: CAN Gateway (J533)       Labels:. 8T0-907-468.clb
   Part No SW: 8R0 907 468 N    HW: 8R0 907 468 C
   Component: GW-BEM 4CAN-M H11 0056
   Revision: 1Y070028    Serial number: 2841Y13921081D
   Coding: 80C303FF00
   Shop #: WSC 02391 785 00200
   VCID: 4ACD6103BCBFD387009-801E

   Subsystem 1 - Part No SW: 8T0 915 181     HW: 8T0 915 181
   Component: J367-BDMHella  H03 8041
   Serial number: 2232061403
This tells us that battery adaptation is available (and expected) after replacing the starter battery. VCDS will have other useful diagnostics for monitoring the condition of the starter battery, e.g.: https://forums.ross-tech.com/index.php?threads/7339/ --g
 

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Discussion Starter · #14 · (Edited)
Ok, so I managed to connect the VCDS cable and do a full scan. There were fault codes dating back to 2008! I don’t think it’s ever been scanned.
Looking through the results, and bearing in mind, this is the first time I’ve ever looked at a VCDS scan, I can see several recent (as in the last 2-3 weeks), faults stored that would seem to relate to the issues that I’m having. There are also a couple of power management codes stored, which I would guess relate to the low voltage on the old battery, as has previously been suggested. I have attached screenshots of the relevant sections, so if anyone can point me in the right direction as to what these specifically relate to I could really use the insight



Gadget Font Audio equipment Personal computer Display device
Computer Personal computer Font Gadget Audio equipment
Font Gadget Audio equipment Technology Electronic device
 

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@Travis_N444VRO : A general process for troubleshooting with VCDS:
1. Auto-scan and save to a log file on your PC/laptop.
2. Clear all codes.
3. Drive the car for a bit.
4. Run Auto-scan again and save to a (new) log file on your PC/laptop. We're definitely interested in any NEW DTCs (fault codes) that are reported.
5. Copy-and-paste text from the Auto-scan of modules showing fault codes (only!) here inside a "CODE" block -- CODE block starts wtih "{CODE}" and ends with "{/CODE}" lines -- replace the curly-brace '{' '}' characters with square-braces '[' ']'. We really don't need to see the entire Auto-scan log file.
6. We'll go from there. --g
 

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Energy management is active. That is causing a ton of errors that may not be errors. You need to resolve that.
I see component protection is also active on J519 central electronics module. Was this replaced?
 
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