Not so remote central locking

Intro

I don't remember having an issue with the remote central locking. I didn't really take any note of it whatsoever.
There was however only one genuine key so I bought another off of eBay. I tried to add it to the vans memory by using the one key in the ignition and the other in the door technique that is shown on many youtube videos. Around here I gained my window not working fault mentioned later in this blog and I was unsuccessful in adding the keys remote to the system for a nice double fail.

Key?

As time wore on the remote range became noticeably worse, only working with the remote close to the vehicle. I swapped the battery and internals between the keys as I didn't have the VCDS at the time to program a new immobilizer but the range did not improve with this swap. 

Are you hearing me?

With the transmitter side seemingly okay, I next looked into the receiver side. 

From what I could tell, all central locking was dealt with the Comfort Control Unit (CCU) and by now I was well into my electric window fault diagnosis which was leading me in the same direction. My next step there was a new CCU and my remote central locking fault was starting to agree with it too.

"Two birds, one stone"? I thought.

Well as you may already know it was not to be. not even one bird and now I have two CCU's. Hmmm.

Aerials

This got me thinking as the van must have an antenna of some description somewhere for the receiver. The tricky part was finding out where it could be.
Searching on blogs lead me down some interesting paths. There was very little coming up for the T5 at all so I ended up looking at other VW's of similar vintage:
The Passat has two Co-axial cables which was a no started for the T5 which just has two block connectors going into the CCU.

This One for a Mk IV Golf which caught my eye talked abut extending the stump of an aerial up into the roof lining. This was of interest as it was just a single wire running up from a block connector so could be plausable.

There was no similar wire on the T5 block connectors so again I was drawing a blank.
But without a dedicated wire this made it more likely that the aerial was an internal part of the CCU.

After a bit more digging online I spotted a difference between the T5's circuit board and those of other VW cars of the era.
The Passat CCU on the right, which is very similar to the T5's, and the Mk5 Golf below; lack the plate loop that the T5 has in its bottom left corner.


This made it a pretty strong candidate for being the aerial on the T5's CCU.

Pretty crap eh?


Well seeing as I had a spare CCU kicking about I thought I might try extending it's aerial to see if I could boost its reception.

First off I drilled two holes in the aerial with a cobalt drill bit then cut it in half bending the two half apart.

Then with a Maplin special solding iron (that's my excuse), I soldered two lengths of speaker cable onto each contact then soldered their ends together to make one long wire.

I then wrapped all of the connections in electrical tape to as to prevent shorts.

To allow the cable through the case I cut a hole in the top casing is a way that the case can be separated and wires removed without it being a pain..

The part of the cable passing through the hole I taped to prevent chafing and provide a bit of a weather seal.

Finally I reassembled everything and trudged out to the van.

I swapped my newly modified CCU for the one fitted and programmed the key back into it as its signal had moved on since I had last used this CCU.

The new aerial wire I ran up either side of the drivers seat back (I have leather seat covers so it sits nicely under there) in a large loop taking up the whole seat back. This just leaves the short lenght of the wire passing up to the seat back from the CCU visible.

The Result?

A bit more than I expected that's for sure.

Well I was expecting it to not work at all, much as most of my hair brained ideas do, but this one did and the improvement was noticeable!

Whereas before my range was pressed up against the drivers door, rear door glass or very near the sliding door, it was now up to 5 meters away from either side of the van and working up to about a meter away from the front or rear.

RESULT!

Further improvements?

Well this little test has proven the theory so I will be expending upon it soon.

I intend to put a loop in the roof lining for a tidier and slightly wider coverage. I am cautious of making the wire too long though as this could fall into the trap on the CCU not being able to provide the power it would require to work.

Secondly I would like to tidy up and better seal around the top of the CCU. I't not imperative as, lets be honest, we already know the damn thing is good enough at filling with water anyway but it would make me feel all warm and fluffy inside anyway.