[volkswagens-for-life]

Alright so what I'm thinking here is either that rear battery is completely cooked and it won't hold a charge, or there is a drain in the system, or the alternator is bad.

If you take the rear battery out you might have an automotive store near you like we do in the states and they can put it on a test machine and tell you if the plates are shot or if it's just completely wrecked or what.

If there's a drain in the system you should be able to use a Multimeter and monitor voltage and amp when everything is turned off to monitor draw. You should be able to find some technical drawing somewhere that should tell you what the draw should be when everything is turned off.

In the states we have automotive stores that can test alternators while the vehicle is running. They put a load test on it and they can tell you if it's charging or if it's erratic or what. If you don't have one of those locally, you can do your own work using a multimeter also.

 

[VW_lover_2001]

The rear battery had a full charge after 7 months of non daily driving.

The front battery (new in March) is the one that was low.

Am thinking the alternator must be working if the rear battery stays well charged.

Am leaning towards a power drain too but don't know what I'm doing with electricity lol

 

[RocketTech]

Your Front battery probably has a dead cell. To confirm, pull it out, charge it over night. Pull it off the charger, let it sit for an hour. Put a voltmeter on it. Battery voltage should settle to ~12.6V. If it settles to a lower voltage, it has a dead cell or is otherwise internally damaged.
The Red w/Yellow wiring would supply power to a headlight relay OR be the wire to trigger the relay, depending on the wire gauge.

 

[VW_lover_2001]

Thanks for the wiring info. That makes sense as I have a headlight error message. The front battery is brand ne and should be 100%.

Will give it a shot.

 

[nickyt]

I test for a dead cell by putting the battery under a slight load and watching the voltage. I like to use an old 55w halogen foglight, but you can often do it this way.

Put the volt meter of the battery. Assume it reads 12.3 volts.

Turn on the headlights or hold down on the brakes. Turn some old school light bulbs on is the idea. This will not work if you hook a LED bulb, they do not consume enough current (amps) to make the test work.

If, with your old school light bulbs running, you see something like 12.3 before to 12.1 now, all is good.

If you see 12.3 go to 10.9 or 11.1 (a big drop over .5 volts) then something is wrong with the battery. I have seen a battery that read 12.5 volts drop to 9.8 volts when I put a simple load on the battery.

Anyway, that is how I test for a dead cell.

 

[nickyt]

If your under dash ticking for one minute at startup is consistent, I would be tracking that down.

Also, any VCDS errors present? Can you post a full scan?

My thought is that it is a relay clicking. If you read thru the electrical ssp, you will notice that the system does a lot of handing of the alternator current. They go thru the relays. Just think of the relays as a switch that the computer can turn on or off.

Here is the top of my head memories. They should be "mostly" correct.

As above, the of the dual batteries run different parts of the car. It is mostly safe to think of them as the car battery and the starter battery, although that is not 100% accurate.

In case one of the dual batteries is dead, relays can click over and run off of a single battery. So, you can have...
1. dual battery start.
2. front battery start.
3. rear battery start.

Now that means there are relays to switch over to these other modes. We know that some of the high current relays in the Touareg are prone to burn out the contacts on the relays. When relays are switched on and off, they often make a click sound.

It is pretty easy to imagine a situation where the tourag ecu switches on one of these relays. It would then look for a voltage change. IE: if we just hooked the front battery up to the alternator, it should go from around 12.3 volts to around 14 volts.

Now the ECU sees that the battery stayed at 12.3 volts. So, it switches off the relay, waits a small amount of time and turns it back on. Repeat-repeat-repeat. After about 60 seconds, the ecu gives up (times out) and the clicking stops.

 

[VW_lover_2001]

Thanks Nicky.

Will report back when I get a result.

 

[VW_lover_2001]

Thanks Nicky for the detailed explaination.

Low voltage wiring issues

Mk1 Treg V10 tdi with intermittent low voltage/random fault codes that may be wiring harness related. Have finally got access to rhe cabin floor wiring harnessses. First splice I came to was both corroded and the wires had also separated from one another. Have twisted them together so...

www.clubtouareg.com

I didn't realise that it was so complicated.

I miss the good old days when it was the battery, alternator or starter.

 

[RocketTech]

It really is still that simple- it just takes a little more effort to make it that way. It's intimidating to troubleshoot the whole vehicle at once, that's why you isolate components and test them. I agree it's not likely to be the alternator or starter because of the information already provided.
A fully charged, unloaded battery at rest (voltage not changing) has a voltage of 12.6. Lead acid batteries have 6 cells, each at a nominal voltage of 2.1 volts. So if you have a resting voltage between 10.5 and 12 volts, you suspect a dead or weak cell. Sulphation or a damaged internal grid can also be the cause.
It's a simple test to perform with almost no tools and gives definitive results.
If the battery tests bad, take it back and get another under warranty. If it tests good, we'll be looking for a short or other key-off high draw.

Thanks Nicky for the detailed explaination.

Low voltage wiring issues

Mk1 Treg V10 tdi with intermittent low voltage/random fault codes that may be wiring harness related. Have finally got access to rhe cabin floor wiring harnessses. First splice I came to was both corroded and the wires had also separated from one another. Have twisted them together so...

www.clubtouareg.com

I didn't realise that it was so complicated.

I miss the good old days when it was the battery, alternator or starter.

 

[VW_lover_2001]

Hi Nicky,

Low voltage wiring issues

Mk1 Treg V10 tdi with intermittent low voltage/random fault codes that may be wiring harness related. Have finally got access to rhe cabin floor wiring harnessses. First splice I came to was both corroded and the wires had also separated from one another. Have twisted them together so...

www.clubtouareg.com

I have OBDeleven instead of VCDS.

I could post screenshots of each error code?

 

[VW_lover_2001]

When i had the seats out and the carpets up to inspect the wiring splices I found a corroded wire that didnt have an obvious splice.

I ended up soldering it to the only other wires that were unspliced coming from the other opposite way but the gauge of the front wire (pictured) is larger than the two coming from behind the driver's seat.

 

[VW_lover_2001]

The new ticking noise is coming from below and to the right of the steering wheel just like the picture.

The control unit for on board network sounds expensive.

 

[RocketTech]

Cut the ends and strip to bare copper, re-splice. They most likely carry a switching voltage to a relay for controlling lights.

 

[VW_lover_2001]

Have re-spliced it yesterday. Both came from brhind the driver's seat towards the pedals. So have put them with the only wire that didn't have a partner. Which is the slightly larger gauge wire from the picture before.

No change to voltage or error codes, including the headlight error message on the dash.

Have a feeling that the power control module J519 is the problem. Maybe getting wet from the leaky front windscreen

Does anyone know if the J519 - onboard power control module needs recoding when replaced or is it plug n play?

 

[Hampton52]

The water on my 2005 Right Side floor was from the firewall and not the windscreen / front glass.

Leak on drivers side firewall help!?

So I posted yesterday about removing the fuse box under the hood. I have also posted before about the total wet carpet (under) and battery drain issues. Anyhow, today I was out to clean the Bulk Head some more and then proceeded running a hose on the drivers side windshield and just below the...

www.clubtouareg.com

And my sonic welded splices rusted away.

Access wiring under under left front carpet

So, I've encountered the warning light armageddon, and I believe it's almost certainly the result of some corroded wire splices under the driver's (left) side carpet since I've just addressed leaking sunroof drains. I've searched around and didn't find any how-to's or tips for actually...

www.clubtouareg.com

955/957/958 Cayenne DIY: Wiring problems due to moisture - Rennlist - Porsche Discussion Forums

DIY - Cayenne (955/957) - 955/957/958 Cayenne DIY: Wiring problems due to moisture - Are you getting all these errors when you try to start the car? Press Brake Pedal, and you pressed it? Tired of searching the internet, and being told it is just the wires in the drivers side failed, but no...

rennlist.com

https://static.nhtsa.gov/odi/tsbs/2014/SB-10056337-3812.pdf

 

[SUPERWAWIS]

Mk1 Treg V10 tdi with intermittent low voltage/random fault codes that may be wiring harness related.

Have finally got access to rhe cabin floor wiring harnessses. First splice I came to was both corroded and the wires had also separated from one another.

View attachment 238177

Have twisted them together so there's no confusion when the soldering starts tomorrow.

Also found a lone wolf with an oxidised end. Its a red wire with a yellow stripe. There's no other half to it along the remainder of the harness so am guessing that it may have come out of this splice which has three separate wires in it already?

View attachment 238178

View attachment 238179

If anyone could point me in right direction it would be appreciated.

There has been a battery drain associated w/ the alarm. Try not locking it to verify.

 

[VW_lover_2001]

Thanks Superwawis. I'll give it a try.

 

[jmcnorvell]

1st attempt at soldering.

Is this enough solder? Lol

View attachment 238190

Sorry for being late to the party.
The soldering is not acceptable (sorry I know it's a first attempt)
I just repaired a V8 with same issue and there were 3 or 4 distinct pairs of wires plus larger Black cables that are seemingly welded together.
If your large black cable have sperated they are very hard to solder and require a larger iron.
I would recommend instead grabbing a brass cable junction screw type connector available at hardware store electrical section.usually wires can enter the connector from both ends. Then insulate with at least two layers of heat shrink tubing.
I usually coat with wax before applying the heat shrink so it's water tight and repellent. Best to use a hot air gun but soldering iron is acceptable to shrink the tubing just use the shaft of the iron not the tip.
Soldering tips: do not use plumbing solder for electrical joints.
Cut back any oxidized wire and strip to clean copper or silver (tinned).
You should use a rosin core solder
Strip back the ends about 1/2" and twist the copper ends together. Heat the twisted wires until the solder melts onto the wire
You should apply a small amount of solder to the iron for better heat transfer.
Don't glob it up on the iron and then try to apply it to the wire.
Feed the solder into the hot wire joint and it should flow easily and neatly.
Check wiring diagrams which are available online.
The low voltage is probably due to the Energizer connection to the alternator being bad. Is your battery light staying on? If so it confirms no or low voltage from alternator.
I really hope the alternator is not bad as that's a big PITA!
Hope this helps and good luck 🙏

 

[RocketTech]

I recommend against soldering connections in a vehicle. Mechanical crimps, when performed correctly, are far more reliable, robust, and safer. Use a ratcheting crimper with dies for the crimp connections you are using. Do not use screw-down connections.
I work in an industry where connections can literally mean life or death. Crimped connections are rated orders of magnitude higher in conditions where vibration and mechanical stress is an issue. This is why all the factory connections on your vehicle are crimped, not soldered.
Heat shrink is a good practice. Use a heat gun, not a lighter or soldering iron.

 

[VW_lover_2001]

Hi JMC,

Thanks for the step by step walkthrough.

The rear battery is fully charged after 7 months of not quite daily driving so am presuming the alternator itself is working and that the failure is somewhere within the all the cables, junctions and relays?

I do have a warning message on the dash that the sidelights are switched on (when getting out) but they're not.