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What is Auto Hold?

Auto Hold is the function that prevents the car from moving backwards when we do not keep the foot on the brake. If we stop the car in traffic, the auto hold function keeps the braking pressure we applied last time on and we can get the foot off the brake. If we stop on a slope and have to stand there for various reasons, we can take the foot off the brake, plus it helps to move off, the car will not go backwards.

Since my car did not have Auto Hold and the retrofit is not expensive, I decided to do it and document everything for others who want to do this retrofit.

Project cost: It depends on what the price you get this button at and whether you make the wiring alone or not. Price range is from 17$ and 70$. It cost me around 19$.

Installation time: 3-4 hours

Encouragement picture: 🙂

What you’ll need:

• Auto Hold Button, OEM code: 4M1927143 B. Also fits A5, Q7, Q5, of the same generation. Taken from dismantling, with plug and a few inches of cable, 16$.
• Cable for the Auto Hold button. You can find it on Aliexpress, in case you don’t want to do it yourself as I did 15$
• Cable tied, about 3m. I used a 2mm double cable.
• If you buy the button without the plug that goes in it, you will find it with the code 8W0 971 636B
• For the pins that fit into the T37 connector, I used metal pins from another socket I had, like the ones in the picture below. If you don’t have pins like this, you can search for the original pins, code 000979009EA. 2 Pins required.
• Torx set, tubular, plastic spatula for disassembly
• Soldering gun, solder, heat shrink tube, insulating tape
• Multimeter
• Coding interface, I used VCDS 17.1 and OBD11 to delete some errors that were not cleared with VCDS.

Connecting the wires

2 wires are attached to the hand brake button, POSITIVE and GND, and 2 wires are connected to the T37 connector A and B from J519 BCM under the steering wheel, as follows:

PIN 1 from Auto Hold on connector B (white interior, right side) at PIN 31

PIN 2 from Auto Hold is connected to the (brown) wire corresponding to PIN 6 of the handbrake button. This is GROUND.

PIN 3 from Auto Hold on connector A (black interior, middle one) at PIN 17

Pin 4 of Auto Hold is connected to the wire (white-red) corresponding to PIN 5 or 7 of the handbrake button. This is the POSITIVE pin. Check and see where you have POSITIVE pin. Some say it’s on PIN 5, but mine was on PIN 7.

Later edit: I noticed that the Auto Hold button is lit all the time and does not turn off like the others when the car is locked. I blame the incorrect connection of the POSITIVE PIN. I will dissemble it one more time and I will make checks, move PIN 4 of the AUTO HOLD button to PIN 5 of the parking brake button or to a PIN without POSITIVE when the car is locked.

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Ok, now let’s code it with VCDS

I recommend that before you do any coding, to back up your current coding on your machine. Store that long number that appears on Long Coding. After installation, the Auto Hold button must be coded as follows:

Module 09, Long Coding, Byte 15, Bit 6, from 0 to 1
Module 03, Long Coding, Byte 18, Bit 6, from 0 to 1
Module 03, Long Coding, Byte 30, Bit 1, from 0 in 1

Some Tips

• Find the Auto Hold Button on eBay. It’s much cheaper.
• The plastic spatula helped me a lot in disassembly, so don’t start the job without something similar
• The center console should come out completely, not just the ornament above. It has a lot of metal clips that are hard to remove, so be patient and have a durable spatula. Watch the video.
• If you are making the wiring alone, write down the colour of the wires that you have in the connectors under the steering wheel, before reassembling the center console.
• T37 Connectors have a mark on them, A and B, see the picture above.
• The fuse box’s cover comes out by sliding it up after you removed the screw.
• The plastic on the threshold comes out quite hard and has many metal clamps that I recommend you do not miss and the ones that will jump (for sure they will jump) to put them back on the plastic.

I hope my indications are helpful. Don’t forget to subscribe on Youtube and Like to my Facebook page. If you have any questions, leave them in the comments box bellow.

Update: I made the Reversing Camera Retrofit on my car. Check my article if you want.

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