[TheLizardKing]

I had replaced the stock rear dome light in my GT TSI with a nicer unit some time ago. It was a plug-n-play replacement, and provided more illumination (3 bulbs compared to 1in the stock unit) as well as individually selectable map lights for the driver and passenger. Details here (My pre-worshipped Volkswagen Polo GT TSI with lots of DIYs).

Some time later, my DIY partner Viraat13 shared this link with me. It was the dome light unit for the Passat B5, with backlit switches and ambient LEDs. Viraat was very keen on installing it. We both did some research, and concluded regretfully that it would not fit the Polo. It stayed at the back of my mind, however.

As luck would have it, while browsing for some other informarion, I recently came across this thread on the UK POLOS forum, and learnt that the Passat unit can indeed be fitted in the Polo. I shared this news with Viraat, and it was game on!

The Passat unit has a 6-pin flat connector, and we need an adapter harness to power it from the stock front dome light connector. In addition, the backlight and ambient LEDs need a power source, which is accomplished by tapping the headlight switch connector. This is a straightforward DIY, and not much can go wrong.

[TheLizardKing]

Main Items

1. Dome Light - 1 no. (VW Part Number 3BD 947 105 2EN)

   Source: AliExpress
   Price: $30.15 + $2.08 shipping

Connectors + Terminals

1. 4B0 971 993 (1 no.) + N10 318 905 (3 nos.)
2. 3B0 972 706 (1 no.) + N10 335 807 (4 nos.)

Source: I had already sourced item no. 1 from Boodmo for my Rear Dome Light mod (VW Polo DIY: Installing the OEM Rear Dome Light). Item no. 2 was included in the AliExpress shipment of the Dome Light.

Consumables

1. 1 mm sq. electrical wire
2. Quick splice connector - 1 no. (example)
3. Harness tape

[TheLizardKing]

1. Torx screwdriver with T20 bit.
2. Crimping pliers for terminals (example)

[TheLizardKing]

1. Preparing the Harness
   
   
   

   Referring to the above diagram (source), prepare the adapter Harness. Be careful while crimping the terminals, since they cannot be reused. If you have never done it before, buy a couple extra to practice. They are pretty cheap. Also pay attention to the pin numbers while plugging the terminals into the connectors. If you make a mistake, you will need a terminal extraction tool (example) to correct it. I removed the terminals from pin nos. 2 and 6, since we do not need them.

   

   Here is a picture of the harness ready for installation. Please ignore the lower branch of the Harness; it powers the Rear Dome Light.

2. Removing the stock Front Dome Light

   Refer this (VW Polo DIY: Upgrading cabin light, headlight switch & installing footwell lights) post by Gannu for instructions.

3. Installing the Harness

   Plug the female connector of the Harness into the male connector of the stock harness for the Front Dome Light. Route the long wire (pin. 1) from the male connector of the Harness through the headliner, down the back of the A-pillar trim, and into the area under the dashboard.

   

   Pop the headlight switch out, and unplug its connector. Use a quick splice connector to tap pin no.17 of the connector and crimp it to the end of the wire routed above. Plug the connector back in, and reinstall the headlight switch.

4. Installing the new Front Dome Light

   This is the easiest step, because the new unit fits perfectly into the existing frame in the headliner. However, it does not have any retaining screws like the stock unit, and is held in place by two plastic tabs on one side and two spring clips on the other. If the unit seems to be loose (Viraat faced this problem), just pull the clips out a bit so that they press more firmly against the mounting frame.

[TheLizardKing]

The Passat unit has FOUR bulbs, which is a vast improvement over the stock unit. In another example of inscrutable German logic, the operation of the side buttons is a little counter-intuitive. They are depressed in the OFF position, and pop out when pressed ON. It is usually the other way round.

Here is a picture of those sweet LEDs, which were the primary motivation for this DIY. The backlit switches really up the coolness factor of the car, and as a bonus are much easier to find and operate in the dark.

The two ambient LEDs in the unit cast a beautiful red glow on the gear knob area. Night time drives are definitely that bit more enjoyable now.

In conclusion, this mod provides both aesthetic as well as practical value, and also has the advantage of being a pretty easy DIY.

Thanks for reading.

[Aditya]

Thread moved out from the Assembly Line. Thanks for sharing!

[Viraat13]

Yes! Another successful mod.

VW has really left us in the dark: no rear footwell lights, no rear dome lamp, a poor main dome lamp, no glove box light, no light in the trunk.

You've fixed it all!

Only the vanity light remains.

[TN13Sleeper]

Nice DIY with clear technical information. If one needs better illumination, this is the way to go. I'm a big fan of the theatrical dimming when turning Off/On. Hence I've stuck with the incandescent yellow lights. The common upgrade done by most people is swapping out the stock bulbs for blindingly bright LEDs which miss out on the smooth dimming due to the nature of their operation.

[anarchy_99]

Making your own harness for this is quite a pain. I started looking online and came across a few sellers with readymade harness. The harness was high quality and straight forward. Bought the harness and installed the lights easily.

[TheLizardKing]

Originally Posted by TN13Sleeper

I'm a big fan of the theatrical dimming when turning Off/On. Hence I've stuck with the incandescent yellow lights.

Same here, mate. I don't have a single LED anywhere in my car. Also, I didn't know that you lose the theatrical dimming effect with LEDs. Will file that away in some corner of my mind.

Originally Posted by anarchy_99

Making your own harness for this is quite a pain. I started looking online and came across a few sellers with readymade harness. The harness was high quality and straight forward. Bought the harness and installed the lights easily.

Well. With the right components and tools, the harness can be prepared in less than 15 minutes. If you are not a DIYer, however, it can seem quite a pain. In my case, I had made a harness anyway for the rear dome light mod, so it was just a matter of swapping out the stock male connector for the new one. Please share details (seller, price, etc.) of the harness that you purchased, so other forum members can benefit.

[Gannu_1]

Originally Posted by TheLizardKing

I didn't know that you lose the theatrical dimming effect with LEDs.

Not true.

The theatre dimming effect is very well present even after you swap the incandescent bulbs with LEDs. The effect is a little more pronounced with bulbs since the filament douses the light gradually whereas with LEDs it is instant.

The gripe with the swap is, cheaper LEDs may emit a faint light when they are turned off, due to the residual current in the circuit. Factory fitted LEDs (like those in the new Passat for instance) won't.

[anarchy_99]

Originally Posted by TheLizardKing

Same here, mate. I don't have a single LED anywhere in my car. Also, I didn't know that you lose the theatrical dimming effect with LEDs. Will file that away in some corner of my mind.



Well. With the right components and tools, the harness can be prepared in less than 15 minutes. If you are not a DIYer, however, it can seem quite a pain. In my case, I had made a harness anyway for the rear dome light mod, so it was just a matter of swapping out the stock male connector for the new one. Please share details (seller, price, etc.) of the harness that you purchased, so other forum members can benefit.

Hi
I had bought the harness from AVS Tuning in Mumbai. I paid 5,000 for the light and the harness. They sell only harness for 2,500. This was back in 2015.
Their contact no. is 9867572757

[TN13Sleeper]

Originally Posted by TheLizardKing

I didn't know that you lose the theatrical dimming effect with LEDs.

Originally Posted by Gannu_1

Not true.

The theatre dimming effect is very well present even after you swap the incandescent bulbs with LEDs. The effect is a little more pronounced with bulbs since the filament douses the light gradually whereas with LEDs it is instant.

Theoretically, dimming is not lost with LEDs. But I personally feel that LED dimming is just a gimmick. Please see the below illustration taken from led-professional.com

Most of the interior domes have two bulbs. Just for experimenting swap one for an LED and leave the other incandescent as it is. Compare the two dimming.

[adimicra]

This is a wonderful DIY and makes the car feel lot more premium. I don't think I can do it myself but I am definitely interested.
The Aliexpress link shared is not working? Can you please correct it or provide another link?

Also, are the lights LED or halogen?

[TheLizardKing]

Originally Posted by adimicra

This is a wonderful DIY and makes the car feel lot more premium. I don't think I can do it myself but I am definitely interested.

Thanks. This is a fairly simple DIY, but only if you have the right tools. If you are not confident about making the harness, it is available for sale on Amazon Germany (link) as well as eBay (link). You may be able to source it from elsewhere too, if you look.

Originally Posted by adimicra

The Aliexpress link shared is not working? Can you please correct it or provide another link?

The AliExpress link is not working because the seller may have removed the listing. Here is another one. You can also search by part number.

Originally Posted by adimicra

Also, are the lights LED or halogen?

They are incandescent W5W bulbs, easily swappable with LEDs.