2010 T5 Control Unit Issue

[OffCWKlausPRI]

Hello,

I'm working on a California T5 2010 import (Left-Hand Drive) in the UK.

Initially, I was asked to have a look at the camper because the control unit was showing the bottom right battery as low, sometimes empty when in reality it was charged. I flicked through the menus and decided that this battery Icon is actually the engine starter battery and not the house leisure battery which can be seen from a different display menu. It didn't answer the question though as the engine starter battery is good, I used my battery tester with load and it is a really strong battery.

After reading this forum, I decided that perhaps a good ol' fashioned "On & Off" would fix it. I disconnected the engine starter battery and both house leisure batteries. I then reconnected all 3 batteries, but now the control unit will not turn on at all, unless under alternator power or mains power. I have read another thread where someone had this issue and the fix was a faulty relay or blown fuse. In addition to this, none of the house lights come on, though I presume the control panel has to be on for these items to work.

I have checked all the fuses I can find. There are large fuses under the engine battery, there are some smaller ones next to the engine battery. Then there are some behind the drinks holder, under the gear shifter, and finally some under the driver's seat. All of these seem to be okay unless I accidentally missed one. The 80A battery fuse on the 1st house battery and the cube fuse on the 2nd battery is fine, not that the cube fuse would contribute to this issue.

I set out attempting to find the relays, however, I could only find 6 under the engine battery, which I presumed are all engine/cab related and not house/leisure related. Other posts mention the relays under the passenger seat - I have no relays under the passenger seat, so I can only assume it's different for a left-hand drive model. Under the passenger seat are just some connectors and a stereo head unit. Under the driver's seat are fuses, the split charge relay, and a Canbus bypass relay which I believe is used for the towbar.

So, any ideas on how to get the control unit working again under normal battery power? And any suggestions as to why the battery reading is incorrect?

 

[WelshGas]

Hello,

I'm working on a California T5 2010 import (Left-Hand Drive) in the UK.

Initially, I was asked to have a look at the camper because the control unit was showing the bottom right battery as low, sometimes empty when in reality it was charged. I flicked through the menus and decided that this battery Icon is actually the engine starter battery and not the house leisure battery which can be seen from a different display menu. It didn't answer the question though as the engine starter battery is good, I used my battery tester with load and it is a really strong battery.

After reading this forum, I decided that perhaps a good ol' fashioned "On & Off" would fix it. I disconnected the engine starter battery and both house leisure batteries. I then reconnected all 3 batteries, but now the control unit will not turn on at all, unless under alternator power or mains power. I have read another thread where someone had this issue and the fix was a faulty relay or blown fuse. In addition to this, none of the house lights come on, though I presume the control panel has to be on for these items to work.

I have checked all the fuses I can find. There are large fuses under the engine battery, there are some smaller ones next to the engine battery. Then there are some behind the drinks holder, under the gear shifter, and finally some under the driver's seat. All of these seem to be okay unless I accidentally missed one. The 80A battery fuse on the 1st house battery and the cube fuse on the 2nd battery is fine, not that the cube fuse would contribute to this issue.

I set out attempting to find the relays, however, I could only find 6 under the engine battery, which I presumed are all engine/cab related and not house/leisure related. Other posts mention the relays under the passenger seat - I have no relays under the passenger seat, so I can only assume it's different for a left-hand drive model. Under the passenger seat are just some connectors and a stereo head unit. Under the driver's seat are fuses, the split charge relay, and a Canbus bypass relay which I believe is used for the towbar.

So, any ideas on how to get the control unit working again under normal battery power? And any suggestions as to why the battery reading is incorrect?

The Control Panel does not monitor the Engine Battery in any way. It only shows the voltage of the 2 Leisure Batteries and a somewhat iffy % calculation.
The screen shows on the R lower corner either a G for alternator charging, a 2 pin plug icon for the when the vehicle is plugged into EHU and the built in mains charger is working, or a black battery icon to show the vehicle is running from the Leisure Battery.

The rear roof lights work independently of the Control Panel and should run off the Leisure Battery.

1. You say the Control Panel works when the engine is running?
2. With the engine running do the rear roof lights work?

Have you switched the Control Panel On using the L lower switch?

 

[OffCWKlausPRI]

The Control Panel does not monitor the Engine Battery

Ahh, good to know!

1. You say the Control Panel works when the engine is running?

Yes

2. With the engine running do the rear roof lights work?

I didn't think to check this at the time, so that's unknown.

Have you switched the Control Panel On using the L lower switch?

Yes. That switch doesn't even illuminate until the engine is switched. Unlike before I disconnected the batteries when it would work, and turn on and off normally.

The obvious answer is I took out a fuse with a battery lead while disconnecting but I can't find any blown fuses

 

[WelshGas]

Ahh, good to know!


Yes


I didn't think to check this at the time, so that's unknown.


Yes. That switch doesn't even illuminate until the engine is switched. Unlike before I disconnected the batteries when it would work, and turn on and off normally.

The obvious answer is I took out a fuse with a battery lead while disconnecting but I can't find any blown fuses

You should check the fuses with a multimeter or by exchange, not just visual.
I enclose a Fuse layout chart. It may not be exact for each fuse position but the Fuse box and value are accurate.
Also with the engine On, carry out the following.

Check Control Panel Diagnostics.

Control Panel Off and wait 30 secs

Control Panel On

Press and Hold R lower button and then press Control Knob for 5 secs.

New Hidden Menu . Scroll to VW Diagnostics.

If there are any codes shown, take note and then Reset/Clear.

Return to Main Menu.

Switch Off Control Panel using L lower button. Wait 30 secs and Switch On.

 

[OffCWKlausPRI]

You should check the fuses with a multimeter or by exchange, not just visual.
I enclose a Fuse layout chart. It may not be exact for each fuse position but the Fuse box and value are accurate.
Also with the engine On, carry out the following.

Check Control Panel Diagnostics.

Control Panel Off and wait 30 secs

Control Panel On

Press and Hold R lower button and then press Control Knob for 5 secs.

New Hidden Menu . Scroll to VW Diagnostics.

If there are any codes shown, take note and then Reset/Clear.

Return to Main Menu.

Switch Off Control Panel using L lower button. Wait 30 secs and Switch On.

Thanks for the chart, that will help no end! I'll recheck soon.

I did check diagnostics before the issue and after the issue - by chance - there is only one fault which was there since purchase which is 6000 (I think) external temperature sensor short to ground. It's always been like that and therefore not related.

 

[Klakski]

Not only check the fuses with a multimeter but also visual check. Mine had a faulty fuse which we couldn’t find but after a visual inspection of the fuses we found the little culprit. The wire wasn’t burned but very thin.
It still gave reading with the multimeter but it wasn’t enough electricity going through to, in this case, keep the leisure battery loaded. Like 12.2 where 12.8 was needed.

 

[OffCWKlausPRI]

Just thinking, if it works via mains and alternator, it can't be the control unit fuse?

 

[WelshGas]

Just thinking, if it works via mains and alternator, it can't be the control unit fuse?

There is more than 1 fuse for the Control Panel.

 

[OffCWKlausPRI]

There is more than 1 fuse for the Control Panel.

Ah, I could only find it mentioned once in the PDF above, under the seat.

 

[OffCWKlausPRI]

Without changing anything, or checking fuses - because that was tomorrow's job - the controller has come back to life. Indications of a faulty controller?