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95 Posts
Discussion Starter · #1 ·
Hey Guys,

I'm part way through my retrofit of side assist, I don't like the traditional VW Mirror Cover mounted LED strips, to me that seems a little dated, I much prefer the LED in the glass.

I'm 70% of the way complete, thanks to N4S and ONOFF I've got quite far, but wanted to peep my head up here to discuss in the open as things progress.


7N0857521E - Sharan Mirror, Aspherical with LED. LEFT
7N0857522E - Sharan Mirror, Aspherical with LED.RIGHT
5Q0907686C - Golf GTI Side assist radar. RIGHT (Came with mounting bracket from ebay)
5Q0907685C - Golf GTI Side assist radar. LEFT (Came with mounting bracket from ebay)
1 x Side Assist Lane Change Wire Cable Harness For VW Golf 7 MK7 (Ali Express)

Making my way into the mirror housing. Speakers had to come out (Thanks to N4S + ONOFF for helping answer that!).

Motor vehicle Hood Automotive tire Vehicle Automotive exterior

The radars came supplied with mounts, I just made a modified bracket using a Dremel and some old metal.

Hood Motor vehicle Automotive tire Automotive lighting Tire

I made all changes to the EPROM when I was working on installing the new colour instrument cluster.

Font Screenshot Parallel Rectangle Number

Mirror's are yet to be wired into the doors, I'm awaiting on door pins to arrive to add to the connectors.

Wheel Automotive tire Motor vehicle Automotive design Steering wheel

Now..... where I'm stuck: : :

  1. I added some LEDs onto the wiring inside the cabin.
  2. LEDs are always on, one is very bright, the other quite dim. As soon as the ignition is on they're on.
  3. Canbus is connected (into extended gateway) via TPMS.
  4. Fuse is connected, and ground is good.
  5. I stripped the whole bumper off (again) and confirmed wiring the entire way from the front down the loom to the back, on each cable. All good solid connections.
  6. When I go into VCDS to enable 3C (is this the correct option??) there is no comms with the module, it times out.
    -FYI, I do not have the camera, I've read a few posts. I pray hope that it's not required to add side assist.

95 Posts
Discussion Starter · #3 ·
Thanks N4S, that must be it. I'll take the bumper off again tonight and swap them around to see if it resolves.

Q: if I swap master and slave, and all is good. Does it matter that master would be on the left (driver) and slave on the right (passenger)?

Thanks again for all of your help.

95 Posts
Discussion Starter · #5 · (Edited)
Thanks again N4S, okay, stripped the bumper off again, swapped them over - nope, this time the LED's on the doors go out though, then and the same, no comms to module via VCDS.

100% has to be a wiring issue, I did use a multimeter to 'buzz out' each of the connections running down the line.

I will need to go back to the drawing board and check out some diagrams for these radars and troubleshoot further. I'll update as I go... I'm not sure why one LED is lit up full power and the other with less.

95 Posts
Discussion Starter · #6 ·
OK, went out and re-confirmed all cabling, I thought it must be the CAN HI/LOW in the wrong order. Nope.

I used a few write ups online that I found, got the below for the wiring.

Rectangle Font Parallel Pattern Screenshot

Wondering where else I'm going wrong here.

Attempt 1: Swap CAN HI/LOW
Reasoning: When 'buzzing' out CAN LOW/HI using voltmeter, both buzzed, regardless of hi/low cable.
Result: VCDS no comms to controller

Attempt 2: Swap Yellow& Green Grey Mirror LED cables over
Reasoning: Maybe master/slave can detect when the wrong side is connected though cables.
Result: LED on driver side = full brightness, LED on passenger side = None.

Attempt 3: Disconnect Yellow & Green Grey cables
Reasoning: Wrong voltage being fed back via LEDs? Creating some kind of voltage loop?
Result: No LED's,VCDS no comms to controller

12v+ Connected to fuse F29, 15A Rear screen wiper motor
12v- Connected to grounding nut/bolt on drivers side dash, clean earth
Can HI/LOW - connected into extended gateway 7/17 piggyback onto TPMS connectors
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