Voltage/control unit failure. Help needed!

[Ole Olesen]

Hi folks. Since February I have been the proud owner of a VW T5 California 2005. There is however a voltage problem in the camper unit, which I have no idea how to solve.

The problem is as follows:

• According to Control unit the batteries are flat or nearly flat (12,1 volts or less) This is basically the case regardless if the motor running or not, or whether it is connected to 230 volt.
• Neither webasto or fridge works
• Webasto does often work, but will also often cut (when display unit show 9,5 volts or lower)
• Fridge always kicks out (normally when display unit shows 10,5 volts or less). It does however take longer before it kicks out if the fridge is set to 7 than 3 degrees.
• (As far as I know, both the Webasto and fridge unit is programmed to cut if voltage drops too far)
• At times, also the control unit dies out whenever the voltage drops too far (below aprox 9,5 volts)

I have done and checked the following:

• Shunt fix is made to perfection
• Both batteries are brand new and show 12,7 volts when measured on multimeter
• Voltage measured on electric socket (named U Electric socket (12 Volt) in self study programme 329) shows 12,7 volt
• lights flickering When starting webasto

It seems that the control unit is not getting the right reading from the batteries. As far as is understand, the battery status is measured on the shunt (named N162 Battery charge control measuring resistor). My working thesis is:

1. N162 has gone bonkers (it does sound strange, seen as this is merely a metal plate with constant resistance)
2. There is some sort of wiring fault between N162 and control unit

The forum have been browsed close to a dozen times. As far as I can see no-one has had similar issues. Can anyone be of help? I will provide pictures if need be.

Best,
Erik

 

[jts46]

Have you connected it to EHU ?
Check 50amp fuse on battery under wardrobe.

 

[Ole Olesen]

Thank you for quick reply.

- Yes, it has been connected to EHU. The display unit will show between 12,7 and 13,5 volts, but the fridge will cut nonetheless. The control unit also shuts down.
- 50amp fuse checked and ok.

Details regarding voltage:
- When motor running, (G shows in bottom right on control unit panel) voltage reads between aprox 12,5 and 13,5.
- When on EHU, voltage between 12,7ish and 13,5ish
- When shutting down motor voltage drops quickly towards 12,0ish, or lower. I alternates between 10,0 and 12,0 volts.

Problem with webasto kicking out does not occur when motor is running. Fridge will cut regardless of EHU, motor or none of these.

 

[Ole Olesen]

Update:
Had a second check. Lights are flickering like crazy when firing up the webasto. Should indicate earth shunt failure. Made a second ground to the rear leisure battery. No change. Any thoughts on installing a second ground to the shunt?

 

[WelshGas]

Update:
Had a second check. Lights are flickering like crazy when firing up the webasto. Should indicate earth shunt failure. Made a second ground to the rear leisure battery. No change. Any thoughts on installing a second ground to the shunt?

The Control Panel is not getting the correct readings from the Battery Charge Control resister. The Earth Shunt needs to be checked carefully to ensure it has been done properly and that a good earthing Point has been made. Also, remove the extra Earth on the Rear Leisure Battery. Both Batteries must Earth through the Battery Charge Control Resister to give correct readings.

 

[jts46]

Some owners have managed earth shunt repair with fridge in situ. Access through panel in left hand cupboard of sink unit. Me I took fridge out, put a write up in download section.
@admin why is this no longer credited to me?

 

[Emil Silenhag]

Details regarding voltage:
- When motor running, (G shows in bottom right on control unit panel) voltage reads between aprox 12,5 and 13,5.
- When on EHU, voltage between 12,7ish and 13,5ish
- When shutting down motor voltage drops quickly towards 12,0ish, or lower. I alternates between 10,0 and 12,0 volts.

“On EHU or engine running voltage reads 12,7 (12,5) - 13,5”

Should be around 14..!?
What is the actual reading measured on the battery with a multi meter?
Both batteries are new. If you disconnect the to batteries and let them rest for a couple of hours, what is the voltage reading? Are both batteries good? I’ve experienced bad battery one month after buying them (Varta).

 

[Ole Olesen]

Thank you! Fridge unit just came out again. So, I realize the Ground is connected to the chassis in a different hole than reccomended. Will that make a any difference? Have tried the other one before, but I could not find any screws that fit the hole perfectly.

Will have a second go at finding the perfect screw tomorrow.



Made a second ground from the shunt to a screw bolt underneath right front seat. No changes on the display.

As to the batteries: the Control panel shows between 10 and 13,5 volt when motor running. At the same time the multimeter shows 14,1volt when measured directly on the batteries.

Both batteries show 12,6 volt when measured by multimeter. Will disconnect both tonight and do a second test tomorrow.

The shunt looks fine, but has got some brown markings on top. I came across a T4 owner that had burned out the shunt, almost like a fuse. New one ordered, just in case.

 

[Ole Olesen]

Both Batteries must Earth through the Battery Charge Control Resister to give correct readings.

The rear battery is for sure Grund through the shunt, but how can you tell if the one in front is? As far as I can see doesnt seem to have Ground at all. Any thoughts?

Extra Ground on rear battery removed by the way. No change.

 

[jts46]

On mine had a welded nut on the rear wheel arch, that is where i fixed the ground from shunt. Don’t understand why you have run a cable from shunt all the way to base of front seat?

 

[westfalia]

Thank you! Fridge unit just came out again. So, I realize the Ground is connected to the chassis in a different hole than reccomended. Will that make a any difference? Have tried the other one before, but I could not find any screws that fit the hole perfectly.

Will have a second go at finding the perfect screw tomorrow.

View attachment 47079

Made a second ground from the shunt to a screw bolt underneath right front seat. No changes on the display.

As to the batteries: the Control panel shows between 10 and 13,5 volt when motor running. At the same time the multimeter shows 14,1volt when measured directly on the batteries.

Both batteries show 12,6 volt when measured by multimeter. Will disconnect both tonight and do a second test tomorrow.

The shunt looks fine, but has got some brown markings on top. I came across a T4 owner that had burned out the shunt, almost like a fuse. New one ordered, just in case.

That earth that you made doesn't look like the right one to me.
Can you see the one here.

 

[Emil Silenhag]

My working thesis is:

1. N162 has gone bonkers (it does sound strange, seen as this is merely a metal plate with constant resistance)
2. There is some sort of wiring fault between N162 and control unit

Best,
Erik

I think you on to something there. The control panel/camper unit are displaying wrong data? But the actual voltage is normal straight on the batteries, measured with a multimeter? Normal is 12,6-12,8V fully charged. Around 14 V with the engine running, and 13-14,9 when on EHU.
I’ve had problems with a fridge in one California. Turned out to little voltage reached the fridge control unit (underneath the fridge), probably by bad connections/restrictions somewhere. We gave the fridge a new power cable from the rear battery and everything work fine since.

The rear battery is for sure Grund through the shunt, but how can you tell if the one in front is? As far as I can see doesnt seem to have Ground at all. Any thoughts?

Extra Ground on rear battery removed by the way. No change.

Both batteries are feed thru the EarthShunt as seen in the attached picture.

 

[Ole Olesen]

On mine had a welded nut on the rear wheel arch, that is where i fixed the ground from shunt. Don’t understand why you have run a cable from shunt all the way to base of front seat?

No nut welded on mine, but moved the Ground to the preferred place. No change in volt reading on control panel.

The idea with the second cable was to make sure that the Ground was done properly. Removed again now.

 

[Emil Silenhag]

Check the connections for corrosion/oxidation underneath the right hand kitchen cabinets. You will find some connections underneath a plastic cap in the floor of the cabinet. Sometimes there have been water ingress in the past...

 

[WelshGas]

No nut welded on mine, but moved the Ground to the preferred place. No change in volt reading on control panel.

The idea with the second cable was to make sure that the Ground was done properly. Removed again now.

View attachment 47097

You have re-booted the Control Panel software using the Bottom L button? Switch off. Wait 30 secs and then Switch On to show the VW logo.

 

[Emil Silenhag]

Regarding how I connected the new power cable to the fridge, I don’t remember in detail. But it was really logical when we worked on this. My friends California had a non working fridge. We used the Penguin Fault Diagnostic paper. We also had two California’s, one working normally and one with a faulty fridge. There where a relay next to the Danfoss Control unit. We routed a new cable from the rear battery to the control unit and the relay I think. Really logical as said when we worked on it...

 

[Ole Olesen]

So. After hours, and hours on end troubleshooting I finally found the faliure. In the end I had no idea what was causing the reading. I ended up checking the voltage on all sockets, and found two wires with a reading of 10.8volts. The wires came out of the front leisure battery. I made a second wiring and everything now works like a charm. It seems to have been the wire powering the control unit.

Thank you guys for help and assistance!

Best,
Erik

 

[TripleBee]

No nut welded on mine, but moved the Ground to the preferred place. No change in volt reading on control panel.

The idea with the second cable was to make sure that the Ground was done properly. Removed again now.

View attachment 47097

Just to make sure: Why is there no nut on the other side of the shunt? The brown cable is not screwed tight, well not screwed at all?
Or was that while you were busy?