Audi A5 8W Auto Hold retrofit

In order to have your AutoHold retrofit, you will need to buy Auto Hold switch [4M1927143] and wiring harness. I bought my switch from and the harness from Aliexpress. You can also make your own harness, of course.

Once you have your parts ready, you can start running wires and connecting.

Your AH switch [E540] has 4 pins which needs to connect to;

1- Front Electronics Unit [J519] : B-31
2- Handbrake button [E540] : PIN-6 (GROUND)
3- Front Electronics Unit : [J519] A-17
4- Handbrake button [E540] : PIN-5 (+)

Cabling will look like this

Coding is a bit tricky. Use VCDS to code like below;
– Module 9 Byte 15 Bit 6 is set from 0 to 1
– Module 3 Byte 18 Bit 6 is set from 0 to 1
– Module 3 Byte 30 Bit 1 is set from 0 to 1
If your car doesn’t have Adaptive Cruise Control, these will work just fine. With ACC, I used ODIS-E to do the coding, since VCDS cannot calculate binary and update checksum correctly. If you are new to ODIS-E, you will need to have au49 workspace and its files in order to code properly.

Here is the result

f30 wing mirror retrofit notes

Retrofitting dimming and folding mirrors requires 2 cables to passenger mirror.  LIN bus and power.

Old mirror pin layout (6 pins)

  1. Mirror Heating  –> not used
  2. Turn Indicator –> Pin 2
  3. Ground –> Pin 3
  4. Vertical Adjustment –> not used
  5. Ground –> Pin 4
  6. Horizontal Adjustment –> not used

New mirror pin layout (5 pins)

  1.  Empty
  2. Turn Indicator
  3. Turn Indicator Ground
  4. Ground (heating and folding)
  5. LIN bus
  6. Power

I’ve connected LIN from A173*4B Pin 27 which was already empty. I ran the cable to the mirror. And for power I used the rear fuse box. The missing ground cable is connected to pin 3.

Driver’s side is plug and play.  Install your new mirror and window switch.

After finishing connections add 430 to FA and code FEM VO.


F30 dimming mirror retrofit notes

  • Locate your rain sensor, behind the mirror.

  • take out the pins of your dimming mirror.

  • connect cables according to table below.

Rain sensor;

PIN Type Color
1 + Red/White
2 LIN Violet/Grey
3 Ground Brown/Black


PIN Type Color
3 + Red
6 LIN Black/White
10 Ground Brown
  • Coding is required.

Without VO;

FEM_01 > PfInternalMirror 3120 > ISP_EC = aktiv
FEM_01 > PfInternalMirror 3120 > ISP_KOMPASS = nicht_aktiv
FEM_01 > PfInternalMirror 3120 > LIN_ISP_VERBAUT = aktiv
FEM_01 > PfInternalMirror 3120 > PF_INMI_LIN_VAR = ISP_g_EC

FEM with 431 option