Strange electrical problems Mk7 2010 2.2 115

[togodwin]

Good evening and thank you in advance for any help.
I bought my 2.2 mk7 9 seat bus middle of last year with no faults however it had been sat for a while. And since about 2 months of owning it faults started to appear.
The crank pulley started squeeling, ive ordered a new one
Drive shaft seal is leaking a little, ive ordered a new one.
Heres where it gets interesting:
At first the central locking was hit or miss and the interior lights went dim. I changed the front battery and everything seemed ok.
I ran a bluedriver obd and it pulled up these codes:
U0401 - invalid data recieved from ecm/pcm "a"
B1238 - center module code
B1d19 - center module code
B13d3 - remote keyless entry code.

I reset these codes and continued on my way in novemver

Over the past few 6 weeks things have started to develop;
Chugging idle when cold
Rev needle intermittently going out
Speed needle intermittently going out
Speed needle sometimes fluctuating
Trip counter randomly resets (when ignitions off)

So ran another scan:
C1a94 - front right wheel speed sensor short or ground
U0401 - ecm pcm invalid data signal a

Cleared, did a long drive

New codes;

C1a94
U0401
P0623 - gen lamp control circuit
B1318 - battery voltage low

Tested both batteries for resting, charging and voltage drop and all seem fine.

All weird symptoms are still happening.
Has anyone got any suggestions?

[tranmx2]

Rev needle intermittently going out
Speed needle intermittently going out
Speed needle sometimes fluctuating
Trip counter randomly resets (when ignitions off)
P0623 - gen lamp control circuit
Could be wiring in consul.

My Mk7 E5. Had rusted rear cluster contacts and doors that did not close = weird indications.
I have found that wires can be 12v live - with key off. There is supposed to be a signal voltage of about 5V.

There is a video on youtube of using Forscan to find wiring circuit faults.
I have not found any wiring diagrams or workshop manual, other info' re van.

[Punto443]

Dodgy ignition switch or corrode blue/red heavy cable attached to the underbonnet fuse box, corroded earth terminals.

[ned]

Why did you only change the front battery, normally there changed in pairs, the rear battery might be knackered now dragging the front one down.

[togodwin]

Thank you, i will have a look behind the cluster for correded connections.
I replaced the front battery because the interior lights were dying, however the rear battery was absolutely fine when tested.
Ive just done a clear and retest and the only 2 codes comming up now are;
P0623 - generator lamp control circuit
B1318 - battery voltage low.
Just checked the batteries and theyre both sat at 12.3 and up to 14.4 when running.

[tranmx2]

P0623 - generator lamp control circuit
As both batteries at the batteries show good V it might be the wiring to/from the generator lamp which is in the consul. The Mk7 E5 has modules which control sectors of the electric system.
It used to be that the generator lamp went out when there was equal V to it, there being two supplies to it. No flow (Amps) no work done.
B1318 - battery voltage low
It seems the battery V is not measured at the battery - as you found them to be good (assuming you checked at the batteries) - So where is the battery V measured? Could be a parasitic draw (there is a test for that) could be a short at where the V is measured or on/at the wire/circuit that is measured.
Modules are used to route/monitor/control the electric system.

P0623 - generator lamp control circuit
B1318 - battery voltage low
It is likely they are linked - could be one fault is causing both DTCs. Years ago the fault could be at the VCR. Voltage Control Regulator.
The VCR is now likely to be electronic on a PCB in the module that controls/monitors that system.

It has been found that solder joints crack and pins come loose corrosion occurs - if you can find the connectors/modules it is as well to have a look.
As already mentioned earths and the starter key - youtube video of changing the starter barrel/contacts.