Significant Electrical Issues

[Sumoto]

Greetings, everyone!

Opted to register rather than remain a prolonged observer. My vehicle is a 2009 Audi 3.0 TDI Quattro Automatic.

A little problem has developed into a significant one. I was transporting my small daughter to the hospital due to her respiratory distress when I received a warning for an electronic parking brake failure, accompanied by an airbag warning light on the dashboard. It is noteworthy that the doors simultaneously unlocked. I suspected potential dampness or an imperfect connection in one of the EPB motors, since I had replaced the rear brake pads three months before.
Upon deactivating the ignition at the hospital, the warning light extinguished for around ten minutes upon restarting the vehicle, only to reemerge thereafter. Subsequently, it would manifest with each engine start, but only after I had driven for 30 to 60 seconds. Subsequently, that day, my sound system entered a "mute" state, with none of the standard buttons functioning to restore sound to my MMI devices.

I purchased VAGCOM for diagnostic purposes. During my diagnostic fault-finding process, I examined all accessible fuses but identified no issues. I detached the 32-pin connection at the passenger side door hinge corner to ensure it was correctly positioned in the connector. After inspecting each fuse with the ignition off and reseating them, I attempted to start the engine. However, instead of just inserting the key fob into the dash socket and pressing once to initiate the engine, I had to hold the key fob down for the starting motor to engage. I currently have 11 distinct "light malfunctions" shown on the dashboard, and my MMI screen is permanently nonfunctional. The Vagcom scan revealed several "under voltage" issues. I opted to recharge the battery as it was depleted, necessitating a jump start from the front booster connectors using my wife's vehicle, which is also a 3L model, therefore the batteries are comparable in amp-hour capacity. Upon installing the new flooded lead acid battery, it lacked a BEM code. I researched many forums and discovered that the vehicle will automatically recognise the new battery. Anticipated that the new battery would resolve all the concerns; nevertheless, it proved ineffective and made no discernible improvement. I am seeing a little battery drain, as this new battery depletes from 100% to 20% after around 4 to 5 days. The key remains in the ignition and cannot be removed; over ten bulbs are nonfunctional despite being in good condition. The airbag warning activates simultaneously with the EPB failure.

I discovered a little accumulation of water in the side panels of my boot, where the electrical components are located. I removed the bungs to prevent water from collecting temporarily and inspected the amplifier assembly and navigation slot for water damage or loose wiring; everything seemed to be in order. Today, I removed the wires tied to the driver's side boot panel, since that was the location of the water intrusion. I examined the wires for any cracking or corrosion of the wire sleeves, but found no issues.

I am utterly exasperated by this situation. This has persisted for five weeks. I get one day off each week, and it is consistently dark when I go out on that day to investigate the matter.

I will provide my whole vehicle scan findings below and seek guidance or suggestions on how to proceed, since I like to avoid visiting a dealership; the vehicle is likely better suited for scrapping.

The automobile is great, and I have maintained it diligently over the years, encountering no troubles apart from wear and use. I would be disappointed to lose my vehicle due to an unforeseen and likely trivial matter.

The central convenience module consistently appears with the airbag control module on various issues in the VCDS scan. Assistance required urgently!

I appreciate any forthcoming ideas.

[RacingNight]

Some individuals may dispute me, but is there not a concern with our older vehicles (I own a 2009 A5 3.0 TDI) where the positioning of the computer and fuses in the trunk allows water to infiltrate, perhaps causing various malfunctions?

[Bitxx]

I have just had electrical issues and, like you, removed and examined every fuse in the vehicle; none were blown.
Upon reinserting them, I encountered an increased number of problems.
I discovered that the blades of all the fuses had oxidised, resulting in incomplete contact, which caused a failure in the affected module when current was applied.
The solution included removing each fuse individually and cleaning the contacts with emery paper.
This rectified all my issues, and after erasing all codes, none have reappeared in the last two weeks.
This may not be the source of your problems, but because it was a complimentary solution (apart from a little investment of time) for me, I recommend doing it first to assess its effectiveness.
I trust this will assist you.

[Sumoto]

I will certainly attempt this straightforward task! The connections exhibited little discolouration, although there were no evident indications that would impede the passage of current; still, it is certainly worth attempting! In the meanwhile, please continue to provide me with recommendations.

[JamesStv]

One certainty indicated by the scan is the absence of contact with the Airbag Module; thus, it may be prudent to begin troubleshooting from that point.

It is likely located under the centre console.

However, your Satnav, radio, and amplifier also lack communication, leading me to believe that water infiltration may be the cause.

[Sumoto]

It seems so; however, my amplifier, satellite navigation system, and radio are positioned much above any water level, therefore I am very certain that water cannot be responsible for the abrupt communication failure. Two days ago, the MMI activated briefly, allowing me to choose between radio stations and use the satnav, however it remained in silent mode permanently. It has not been fried, despite its appearance suggesting such. Two days later, the screen would not power on again. puzzling conundrum

[rauman]

Numerous mistakes I suspect a defective module is overwhelming the communications. I would concentrate on identifying water damage as the most probable cause, given your mention of it. Water may enter from above and inundate the amplifier unit in the trunk; this is well-documented. The convertible roof motor is susceptible to flooding and deterioration, resulting in many mistakes. On the other side of the boot are the fuses and different modules. I would place a fan in the trunk to dry the damp places and inspect for water stains on the different electrical components. Avoid driving through any puddles, since they may indicate leakage from the back vents.

[Sumoto]

My A5 is a normal Coupe, not a Convertible. The vehicle remains still, and hence, no water is emanating from the wheel wells or splashing. I suspected the huge rubber stoppers that cushion the boot lid from slamming, so I applied sealant around them, as well as the little rubber skirts on the lip of the boot at the rear lights, in case water runoff was entering there. However, after a little rainfall, more water accumulates in the side compartments of the trunk. The investigation into the flooding was temporarily suspended while the issues with the EPB and airbag faults intensified, resulting in many fault codes, malfunctioning lights, and a key lodged in the key-fob socket. It is undoubtedly water runoff from an external source that is infiltrating the area.

I am also persuaded that the water served as the trigger for these events, while it may not have been the primary cause of the EPB and airbag malfunction; rather, it undoubtedly contributed to the subsequent problems. I will be working on Christmas Eve but will be available on Boxing Day to further investigate and attempt to limit down the options. I will also use the emery paper technique on the fuses to check for any changes in symptoms.

Is there anybody who knows what regulates the lighting? I have not seen any fuse description that corresponds to a connection for headlights or information on the relay and its location. Or is it everything only processed via the central convenience module? Identical inquiry about the Ignition... From whence does it get the authority to release the key? Fuse/Relay for the solenoid.

Am I correct in recalling that a single click down on the key fob initiates the car's ignition? Is it unnecessary to maintain pressure on the key until the device initiates? I am very certain that my need to keep the key engaged is a recent development. Additionally, when the ignition is switched off, do I recall properly that the steering lock engages, preventing the wheel from turning beyond the two designated locking points? Due to the absence of a distinct "click" and the wheel's failure to "lock," it becomes very rigid without any discernible point of resistance in either direction. However, it may be rotated with considerable force. This may pertain to my key fob not disengaging from the ignition, since I suspect that the use of the steering lock is necessary for the ignition solenoid to release the key fob. It is possible that the ignition is not the issue, and the steering lock may be the culprit.

My head is throbbing; I apologise if yours is as well. 😄

[MutanX]

Did you resolve a similar issue? I too have water surrounding the fuse box on the right-hand side at the rear.

[rauman]

If it is not a vert, then you are likely correct that the water originates from the boot. It is said that opening a damp boot lid results in this phenomenon. I am uncertain, however there exists a discussion thread here about blown amplifiers and Audi's creation of a shield in later models to safeguard the amplifier. I am not a specialist in this area and cannot adequately address your enquiries, however I observed this while re-reading;

    I am seeing a little battery drain, as this new battery depletes from 100% to 20% after around 4 to 5 days.

It also seems significant. The key must function with a single press release.

[HolyRoach]

Is any section of the wire harness submerged when water accumulates? Even if water is not dripping upon it. The loom has many joints equipped with rubber caps. Water may infiltrate these components and compromise the joints, leading to a loss of power to the modules, among other issues.
The front lights are regulated by the power supply module located under the dashboard, while the rear lights are managed by the Body Control Module (BCM) in the back.
The steering will not lock until the key is withdrawn, and the key cannot be extracted from the slot until electricity is supplied to the slot.

[Uneripty]

This is quite challenging. You undoubtedly own one significant issue, from which all other problems likely stem. I extensively utilise WD40 and ACF50 on, in, and under my vehicle over the winter to mitigate these issues, yet my previous 3.2 Coupe never malfunctioned like yours. Your issue seems to have originated from water in the boot; thus, I recommend beginning by thoroughly drying it out. Subsequently, open all connections, dry them, and add grease or WD40 to each one.