Interpreting current flow diagrams

[JariYliJ]

Hi,

Could someone shed some light on how to find physical locations of connection points indicated in the ELSA Current flow diagrams? The ones I mean seem to be indicated with a letter followed by two/three numbers in a circle, for example A203 or B708, or sometimes with just numbers, ie. 366, which would be "Earth connection 1 in main wiring harness" in auxiliary heater control unit diagram (A6 2011 3.0TDI ). Are the physical locations stored somewhere in ELSA?

The reason I'm asking is I'm looking to connect and auxiliary heater to my car and there is no wire harness in place from factory, so I need to make all of the connections separately. I'd rather use the same physical locations to connect the wiring that are used in a factory installation. I'm also wondering if these connection places shown in current flow diagrams are actual connectors of just places where wire splits exist in the wiring looms (seems like they are the latter kind but if someone has solid knowledge I'd appreciate that).

Thanks guys!

[Flash2]

No, the locations of internal harness splices aren't known. And they aren't actual connectors.

I wouldn't over complicate the job. Just connect your wires where ever it's most convenient/easy.

[JariYliJ]

Thanks for the information. Yeah sounds like a good way to go. My concern regarding this was that I couldn't find a convenience CAN bus connection wire anywhere in the engine compartment. The nearest one that I found would be in the passenger footwell (LHD car). I read somewhere that there could be problems with connecting with a long CAN bus wire (voltage drop, interference mainly I guess), but I suppose that's how I'll have to route it then. Of course I'll twist the said wire as suggested in ELSA guide about repairing CAN bus wiring.

[Crasher]

They make lovely comments such as "in engine wiring loom" which is about as helpful as a kick in the balls...

[diecastsink]

Would this help a little? Can be downloaded from erwin.audi.com - all repair manuals for a few quid.
image.jpg

[Flash2]

I read somewhere that there could be problems with connecting with a long CAN bus wire......Of course I'll twist the said wire as suggested in ELSA guide about repairing CAN bus wiring.

If it's a fairly long length why not just use some CAT5 cable that's specifically made for wiring computer networks. It might save you a lot of twisting. CAT5 cable has 4 twisted pairs so you could even double up pairs which will reduce any voltage drop too, although I don't see that being an issue.

[Crasher]

You need to tap the CAN high and low cables into the matching wires in the convenience system bus when doing the aux heater retro fit and then code the CAN BUS unit to see the device, usually in a couple of controllers. ID the convience bus wire colours and they should not be too difficult to find and tap into.

[JariYliJ]

Thanks everyone for the tips! I ended up using t17o - connector in the right A-pillar coupling station (indicated in the picture shared by diecastsink). It was fairly straightforward to get to. There is a large rubber cap inside the wheel arc that leads to very near the A-pillar coupling station. The only problem was that to get the front door sill trim back in it's place I had to partially remove B-pillar trim and while snapping that off, some part of the seat belt adjusting mechanism got loose and dropped inside the b-pillar. Now the front passenger seat belt height adjustment doesn't work anymore haha... That's a minor problem though and will be fixed later on.

The comment about the CAT5 cable was a brilliant one, should have used that... I ended up manually twisting two 0.5 mm2 wires which made the cable quite cumbersome to route through into the front passenger footwell.

Any way, it took some time but the heater is now installed and missing only the metering pump, since I decided to order the pump bracket from Audi and haven't received it yet. I'll connect the electronics and do the coding after I get the pump installed and we'll see if the thing actually works.

[JariYliJ]

Update: Metering pump installed and everything seems to be ready to go. There is only one problem with a fault code "Component protection active" in aux heater control unit. Judging by what came up when doing some research it means a trip to the dealer....

By the way, if anyone happens to have a picture of the correct factory installed metering pump installation in a 4G A6/A7 I'd greatly appreciate this. For the life of me I couldn't figure out how the oem metering pump bracket should be fitted.