Pre fuse box/relay box?

[Colin K]

Hello,
Have been having trouble with my central locking. Mk7 350 115. LWB RWD. She has two batteries and I took out the seat at the weekend to find that the front battery was fried in one cell. Changed the battery and hey presto everything works ok. I did have a bit of a wiggle trying to get the cover off the plastic box to the rear of the starter battery but gave up. Tonight I cannot lock the van and the aux side of things do not work, no lighter sockets working without ignition dim internal lights etc.
Had a fiddle and all I did was again play with the plastic case of the rear box. Giving up for the night pressed the central locking key and all locked up. Is there a fuse or stuff in there that could be loose? Or is it spooked. And how does the blooming thing come off is it batterys and bracket out?

Any help be appreciated, Cheers, Colin.

[MK7 user]

Haha....yes, it's spooked.

Remove seat,
Remove battery retaining clamp,
Remove starter battery,
The top of the pre-fuse box cover pulls forward & hinges down, then pull the cover off the bottom hinges.

See pics....

PreFuse_1.jpg

PreFuse_2.jpg

[Colin K]

Hello thanks for that awsome, so no fuse stopping the aux battery charging (if its flat) but you never know loose relay?

Cheers for the explanation and pics, Col.

[MK7 user]

Alright buddy.

It sounds like there is something loose in there.

[Colin K]

Hello,
Thanks so much for the replies. Central locking has got worse and thought bugger not going to be able to lock her up tonight (rear of van)
So took out the seat, battery clamp and batteries. Removed plastic cover of pre fuse box. Your rught took 10 mins. Checked all of the fuses with meter but new aux battery is almost flat.
Heaven knows why but I decided to jury rig a lead from the pos of the engine battery to the pos of the Aux battery. Low and behold central locking works perfect aaaah. Thought cannot leave a lead from one to the other what if there is a fault? SO. Ran said lead from engine pos terminal to Aux pos terminal with a 15a fuse in line. Kind of think that if I have a major fault it will blow??
So tonight van is locked and have to move on in my testing tomorrow. I am thinking go to the Aux fuse box now.
Any thoughts? Could the relay not be diverting charge from the alternator to the Aux battery?


Cheers, Col.

[MK7 user]

Sorry buddy I've had another brain fart.

You've replaced the auxiliary battery....the Interior lights being dim & Intermittent problems with the central locking point to the new battery not charging - I should of picked up on that from the start.

When you turn the ignition on, relay R1 connects the both batteries together - you'll hear the relay click in....if you don't here it click its fubar....if you leave the ignition on without cranking the engine, the relay clicks out on a time delay (you can hear it).

If the relay is good, with the engine running, put your meter on both sets of battery leads & check the charging voltage....from memory it should be between 13.8 & 14.2 volts.

If the alternator is overcharging or undercharging you should have problems with both batteries (which you don't)....if there is a problem with the split charge circuit it should be apparent with your meter on each set of battery leads.

[thevegman]

My van had all these problems, all of which baffled the local ford dealer, i cant believe that they didn't put a meter across the batteries, after reading this post i did get the meter out and lo and behold the front battery was as dead as the proverbial dodo, and thanks to the expert knowledge of you guys on the forum i have managed to sort it all out with a new battery, oh and i got a refund from the dealer as well.
Many thanks guys.

[Jim Archer]

New battery going flat points to the alternator diode pack going south.

Jim

[Altransit]

New battery going flat points to the alternator diode pack going south.

Jim

Wouldn't they both be flat though, Jim

If only one is going flat, it's more likely to be a failing cell in the battery.