CCU clicking, non starter

[jonjo]

Is it normal for the CCU to click randomly like a relay flickering when you’re in the car unlocked with the ignition off?

Windows, locking, stereo all seem to work ok. I mean the heating is only ever hot and the left speaker drops out ? but I figured those are age related gremlins I’ll get round to one day!

 

[Proghound]

Nope. That sounds like a CCCU with issues. What is the last letter of the part code printed on the top? (or last two letters if they follow the last number).

 

[jonjo]

Nope. That sounds like a CCCU with issues. What is the last letter of the part code printed on the top? (or last two letters if they follow the last number).

AF, I’ve read they are more reliable but not bullet proof. Is there a way of testing how failed it is?…I’ve heard some people pull relays to further diagnose the problem.

8Z0 959 433 AF

 

[2work]

Morning Jonjo,

Your research and understanding is spot on. Whilst it also sounds like a failing CCCU to me, it obviously quite difficult to provide a diagnosis when nothing else is reported to be at fault.

As you have observed on many occasions, this amazing community of ours will go out of their way to assist and provide possible solutions to your issue. This particular situation isn’t the easiest to diagnose and will be a guess at best as you have the more reliable CCCU fitted. If you had an earlier generation CCCU fitted you probably would have been told to replace it as ‘it’s unreliable’, which in most cases is quite true but it’s also been functioning fine for the 15-20 years prior to presenting you with this clicking noise.

The sensible thing to do here is scan your car with VCDS. If you don’t have this capability then have a look at this thread to see who is close by and get in touch with them.

Once you have a copy of your VCDS scan report, post it on this thread and the community will be better able to provide guidance on what to do next, which should be a DIY task.

Without a VCDS scan report we are just guessing.

Kind regards,

Tom

 

[jonjo]

Thanks Tom, as you say, I’ve experienced the great knowledge and help of folks on here and on the flip side, the negligence/foul-play of independent garages (still in progress).

I have the VCDS cable and I’m hoping to borrow a windows laptop from a friend later today. I’m expecting MAP codes as I had an EML pop up after fixing the MAP sensor harness (exposed and frayed). I don’t think, at this stage, they’re related to the CCU directly but I’m often surprised and there has been ECU problems recently.

 

[2work]

Brilliant,

This should speed up the advice we can offer. Before you share the scan report please do desensitise it so you VIN cannot be used elsewhere. Also save the first scan then clear the faults, go for a short drive and scan again, this second scan is the report you need to share.

This will save getting additional advice for legacy faults which you may have rectified some time again.

Personally I’m no expert on the CCCU and it’s circuits yet but will watch your replies later on to see if I can help in any way. There are a few on here who are very experienced in the Comfort CAN who will be along soon enough though Good luck.

Kind regards,

Tom

 

[audifan]

To rule out low voltage, fully charge the car battery and see if the fault clears.

 

[jonjo]

Right, took some time to get a laptop sorted but I have some codes…poor latency on my connection but…

On CCU (DTC46?)
01370- alarm triggered 35–00
01574- request to register
01562- request to register
01562- right rear door 61-10 won’t de-safe
00955- request to register 35-10
00956- request to register 35-10

On engine (DTC01?)
18000- altitude sensor/boost pressure sensor:implausible correlation. P1592 - 35-10 intermittent
17564- request to register

I cleared most of these, (engine codes wouldn’t clear). she still won’t crank.

@audifan I agree, a fresh charged battery could solve the start problem but I did have jumpers from a close parked T6 which gave no joy. Might punt for a fresh battery from halfrauds.

Any insights appreciated!

 

[audifan]

Again try the battery recharge. If you go onto the Ross Tech site there is a listing to explain MOST codes so refer to that.

With unregistered Lite you only ever receive the details for the first fault and a message to register against all subsequently listed faults.

 

[audifan]

Try to recharge existing battery first unless it is old or has failed before. Best place for batteries in my opinion should you wish to replace it is

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[audifan]

The battery terminals could be loose or corroded, the engine earth between the starter and left chassis rail could be corroded or failed internally, especially if you have already had a second battery to try to jump start. Fit a jump lead between the engine block and a good chassis earth point. Temporarily if you held one end onto one of the nearside strut mount locations and the other onto the bare block and have someone try to crank. If this works your earth lead is not working...

 

[audifan]

CCCU clicking can also be down to poor voltages in its circuits.....

 

[jonjo]

Again try the battery recharge. If you go onto the Ross Tech site there is a listing to explain MOST codes so refer to that.

With unregistered Lite you only ever receive the details for the first fault and a message to register against all subsequently listed faults.

Should have mentioned The car is stuck on a hill (sideways sadly and with about 4m of jump space before wall), 20mins walk from my place so a fresh battery might be the option. Or I could carry the battery back and charge overnight.

Some of the modules return an error…
“Too many communication errors to continue” ? (HVAC)
And
“No response from controller”

Can I fix these errors?

 

[audifan]

Try what I suggested with the jump lead on the engine block and chassis. Certainly remove and charge the battery, but make sure you know how to lock and unlock the car before removing the battery and also how to access the boot - and make sure it also works before disconnecting the battery and shutting the boot....

HVAC - well not too much of an issue probably the majority of A2s have HVAC issues with VCDS.


Lets make sure we have good powers and earths and a healthy battery before getting too concerned about other scan issues.

 

[jonjo]

i did attempt shorting the ground to the starter but wasn’t confident of my location choices…the starter brace/arm and one of the top mount bolt NSF.
I’ll try again now. ??

I have cleaned that earth point before. Wiggled that starter ground cable a little in vein hope it might be separated internally ? no joy for broken cables!

 

[audifan]

Just do not accidentally connect the starter positive lead to earth....

 

[jonjo]

Just do not accidentally connect the starter positive lead to earth....

Edited photo in, the far connection is onto mount bolt head. Certainly felt like a more audible click from the starter. The battery and this short ground could get me rolling again. Massive thanks @audifan, nothing better than the support from you guys whilst sat in a stuck a2 during a yellow alert rain storm!

How heavy are these batteries? ?

 

[audifan]

HEAVY.....

 

[jonjo]

HEAVY.....

It was. It got heavier. Around 18kg on the ropey bathroom scales!

All charged up and still no crank.

CCU is clicking away like a lunatic. What causes them to fail on other versions? I’m told the AF suffix is pretty reliable.

 

[jonjo]

To close this out for now…I switched out the 1 yr old REMY starter for a Bosch one, cleaned all the grounds in that area for good measure and starts easily now!