Reading VW wiring diagram

[MarcoT3]

Hi guys, on the top of the VW wiring diagram there is a line marked 31. In the wiki it says this is ground. Am I right in assuming this is a ground within the fuse panel? If so how does this ground get from the fuse panel back to the body? Thanks

[TwinTurbo]

do you have a link to where your looking  VW diagrams usualy have ground along the bottom and feed at the top

[TwinTurbo]

I can't tell what 31 is without trawling all diagrams

but if you look at the first diagram in this PDF you will see the battery negtive connected to the bottom line which is ground. 

https://syncrosport.com/info/wiring/VW_ ... _SP_DG.pdf

[TwinTurbo]

page 61/13 on the left it looks like 31 is tied to ground. I think to answer the other part of your question it is within the fuesbox and is tied to ground by Pin22 on connector D
 

[MarcoT3]

Thanks, it’s the number 31 at the top I’m referring to, yes it seem to go to ground through that connection

[Robsey]

I can confirm that there are a couple of internal ground connections.

Each had a brown wire to the earth crowns on the A Pillar.
These are -

Pin 22 of the D connector. (D22).
This is the main ground for the dash.

Pin 1 of the H connector. (H1)
This is the ground for the radiator 2nd stage fan circuit relay. [Relay 5 terminal 5/85].

The '31' rail is mainly an internal link for many of the relays within the CE1 fuseboard assembly.

[MarcoT3]

Thanks Rob. When I check for continuity with the multimeter across D22 and H1 I’m getting nothing!

The problem I’m having is my blower/wipers/radiator fan are only intermittently coming on when i move the fuse panel, I have already cleaned all the ground crowns and connectors at the back and I’m trying to figure out what else they have in common. I’ve isolated it and The problem is definitely in the fuse panel as when I move it the slightest bit they come on and off!

[Robsey]

Both of those circuits are on the "X" relay or relief circuit.

Ignition live when not cranking position of the ignition switch.

For me, the obvious thoughts are -

a loose connector in the back of the fusebox.
You could locate the D Connector, and give it a firm press into place.
This white plug.



Although to be honest, I would check that all the main plugs are secure in their sockets.
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Other things to affect this could be a faulty or loose relief relay.
In the middle of the relay panel will be a relay with the number '18' or '100' on it.



Really early vans may have a number '24' relay.
But we are talking the early torpedo / euro fuse type fusebox.



You could try pulling this relay out to see if the legs are dirty, or simply replace it with a good relay of the same type.

The relay supplies the high power consuming items, and is wired so that it is ignition live when the ignition key is in the run position,
But power is cut in the crank or start positon to ensure that all available battery power is sent to the starter motor.
__________________

The fact that moving the fuse box has this effect, infers a loose connection.

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Another thought - when moving the fusebox, you are not tugging on the spade connectors for the earth crowns by any chance?
The crowns / spades may be clean, but are they a good tight / secure fit?

I changed all my spades to ring connectors and bolted the earth wires to the A pillar.
No chance of coming loose now, and it is harder for the corrosion to get in.

[Robsey]

As a follow up to the D22 and H1 puzzle.

If you do not have a diesel engine or air con, where a two stage radiator fan switch is usually fitted, then you will probably have no connection at H1.
You will therefore probably not have the brown T shaped plug in the back of the fusebox



Therefore no H1 wire means no connection to D22 via the van chassis. (Earth crowns).

All relay 85 terminals are within the fusebox, hence no identifying connector and pin numbers.

[MarcoT3]

Hi Rob, I just noticed my relief relay slot 8 actually has a ‘53’ relay in it, so not the correct one. I’ll order a proper X relief relay from brickwerks and see if that helps.

The earths all seem fairly tight and aren’t moving when I move the fuse panel so it is unlikely to be them, you arrangements looks a lot more reliable though!

I have had all the rear connectors in and out several times and cant see any major corrosion and they seem to be seated properly. 

Would I be correct in saying the X relief relay gets its power through the light switch via ignition switch?

[Robsey]

Nope the X relief relay gets it's feed from the ignition switch.

If you had not stated that moving the fusebox is what kills and restores the power, I would have considered burnt contacts in the ignition switch.

Where the weird bit is, is that flashing the high beam via the stalk, often bypasses the relay energising the circuits that you mention.

The 18, 24 or 100 relay has a much higher current rating than the 'universal' 53 relay.