Rear Taillight Wiring

[Skynet]

I am ready to pull the trigger on a set of these and the only thing holding me up is the wiring schematics for the taillights.

Clear left taillight



Clear right taillight


Where are my electrical engineers who can help me out with wiring/separating the OEM Stop/Blinker lights and making them separate blinker and stop lights? I can follow diagrams 90% of the time. I just need to know which wires to tap into. I saw a thread similar to this for the Sportback but the harnesses are different from ours which made it difficult for me to follow. I would also like to wire an enable the rear fog light if possible. I know some others on here have purchased these but have not messed with the wiring. I'd like to do them right when I finally do get mine. Any help would be appreciated.

 

[Anaduff]

I don't think there is that much difference between the Sportback/Tourer...

You should have a voltage tester (automobile logic probe) handy to both find & verify that you've got the right wires.



The general overview is 1) find the front left & right turn signal wires, then spice & run them into the back of the Tour-X, and 2) locate the 'high brake' signal wire and tap off of that. That gives you a brake only signal & the l & r turn signals without the brake.

Specifically, you'll be removing the rear floor deck and both rear inside panels to get access to both the wires & the rear lamp modules. There will be two existing wires (l & r turn w/ brake) which will have to be terminated with an 8 ohm 50W resistor (1 resistor per wire) to keep the BCM module from hyper-flashing the turn signals). You will have to feed 2 new wires from the back interior to the tail lamp modules (the brake only signal) and either install a new pin on the existing Molex (the ones that connect to the tail lamps) connectors or else splice the new brake signal wire onto the Euro lamp module using some sore of water-proof connector.

I double checked the BCM connector pinouts, and the front left turn signal is on connector 5 (X5), pin 2 (Blue/White) and the front right signal is on connector 4 (X4), pin 3 (Green/Violet). The high brake is a Violet/White wire somewhere leading to the lift gate (worst case, tap off of the source at pin 11 or connector X4 at the BCM).


As far as the rear fogs go, no one has found an 'elegant' way to get those to work.

 

[Skynet]

I don't think there is that much difference between the Sportback/Tourer...

You should have a voltage tester (automobile logic probe) handy to both find & verify that you've got the right wires.

View attachment 27922

The general overview is 1) find the front left & right turn signal wires, then spice & run them into the back of the Tour-X, and 2) locate the 'high brake' signal wire and tap off of that. That gives you a brake only signal & the l & r turn signals without the brake.

Specifically, you'll be removing the rear floor deck and both rear inside panels to get access to both the wires & the rear lamp modules. There will be two existing wires (l & r turn w/ brake) which will have to be terminated with an 8 ohm 50W resistor (1 resistor per wire) to keep the BCM module from hyper-flashing the turn signals). You will have to feed 2 new wires from the back interior to the tail lamp modules (the brake only signal) and either install a new pin on the existing Molex (the ones that connect to the tail lamps) connectors or else splice the new brake signal wire onto the Euro lamp module using some sore of water-proof connector.

I double checked the BCM connector pinouts, and the front left turn signal is on connector 5 (X5), pin 2 (Blue/White) and the front right signal is on connector 4 (X4), pin 3 (Green/Violet). The high brake is a Violet/White wire somewhere leading to the lift gate (worst case, tap off of the source at pin 11 or connector X4 at the BCM).

View attachment 27923
As far as the rear fogs go, no one has found an 'elegant' way to get those to work.

Most of this seems doable. I have the resistor, but I don't understand how to terminate the left and right turn/brake line. Do I place the resistor between each line? And will that line not be used anymore? That's where I'm getting lost at. Sorry for all the questions. This was so much easier 5-10 years ago when the BCM didn't have as much control.

 

[Anaduff]

The existing r & l turn/brake wires (Grey/Yellow for the left side, White/Yellow for the right) will be disconnected from the tail lamp modules but the BCM still has to 'see' the correct current flow or else it will think there's a burned-out bulb. So in effect, the two 8 ohm resistors are put to use as 'bulb emulators' (there isn't any reason you couldn't get a couple of bulb sockets and just re-insert the original tail lamp bulbs--just that the resistors are much less likely to burn-out). So the original combined use wires connect to one side of a resistor and the other side goes to chassis ground. Because I had to extend the original wires (and not having any solid/stripe stock wire) the left/right signal wires connected to the resistors in the photo are red (port side) and green (starboard).

______________________________

 

[Anaduff]

This is one of those things that can keep you awake at night...

I know I mentioned it way back when in a related thread, but it bears repeating just in case. Since the above solution taps off of the front turn signals (which are a combination of LEDs on the headlamp modules & the regular bulbs on the fender repeaters) and since we don't know how much current the BCM can deliver, it's just good sense to replace the 7507 turn signal bulb in the Euro module with an amber LED replacement (PY21W) to drop the rear current load from 1.8A to about 300mA. Also replacing the repeater bulbs with either LED versions or the LED sequential assemblies will also mitigate the load on the BCM. If the battery is in the back, I'd recommend using a couple of automotive relays driven by the front turn signal wires to run the rear signals--then there isn't an issue.

 

[Skynet]

This is one of those things that can keep you awake at night...

I know I mentioned it way back when in a related thread, but it bears repeating just in case. Since the above solution taps off of the front turn signals (which are a combination of LEDs on the headlamp modules & the regular bulbs on the fender repeaters) and since we don't know how much current the BCM can deliver, it's just good sense to replace the 7507 turn signal bulb in the Euro module with an amber LED replacement (PY21W) to drop the rear current load from 1.8A to about 300mA. Also replacing the repeater bulbs with either LED versions or the LED sequential assemblies will also mitigate the load on the BCM. If the battery is in the back, I'd recommend using a couple of automotive relays driven by the front turn signal wires to run the rear signals--then there isn't an issue.

Thank you. I'll take this into consideration. I've already purchased and installed the sequential left side indicators. Since our TourX battery is located up front, will I still need to make adjustments using relays if following the methods stated above?

 

[Anaduff]

Let's see...

You will still need the two 'bulb emulators' in back and the two new (left & right) turn signal wires from the area of the BCM. You would then need to find a +12V battery connection (there should be a few on one or more of the BCM connectors) & check it to make sure it doesn't 'time out'--you wouldn't want your emergency flashers to stop. Then it's just wire two relays (and mount them to something); neg. coils* to ground, pos. coil to the front turn signal taps (from the BCM), +12 battery through an inline fuse to both relay 'inputs', and then the two new rear turn signal wires to the appropriate relay 'output'.

With the above, you have gained the ability to use a real bulb in back--but I think the two relays will cost more than the two LED replacements...

* I'd recommend the relays with the internal suppression diode just so there isn't any kick-back voltage presented to the BCM.

 

[Skynet]

I have One more question. Is it possible to ask the dealer techs if they can perform this function either electronically or by some unknown adapter connecter? When I had my Volvo V50, I had the dealer turn off my {halogen}DRL's. It cost me a little bit but they were able to do through software update/downgrade.
I'm just wondering before I get too deep into this if they CAN (no pun intended lol) do it, that would be an easier route, depending on cost of course.

______________________________

 

[Anaduff]

Not sure which function we're talking about. Disabling the DRL's can be by the dealer--but from what I've read, GM is really big on DRL's being required, and if you want the dealer to disable, GM wants that dealer to have that request in writing with a public service letterhead (basically, the police/sheriff dept.--DRL's not being helpful while on stake-out). Of course they can be disabled, per start/stop cycle, by turning the headlamp switch to OFF (or the headlamp switch module can be 'converted'--that mod is also on this forum). If this is about separating the rear brake/turn signals--that isn't under software control (plus the separate brake lamp wire just isn't there).

 

[Skynet]

Not sure which function we're talking about. Disabling the DRL's can be by the dealer--but from what I've read, GM is really big on DRL's being required, and if you want the dealer to disable, GM wants that dealer to have that request in writing with a public service letterhead (basically, the police/sheriff dept.--DRL's not being helpful while on stake-out). Of course they can be disabled, per start/stop cycle, by turning the headlamp switch to OFF (or the headlamp switch module can be 'converted'--that mod is also on this forum). If this is about separating the rear brake/turn signals--that isn't under software control (plus the separate brake lamp wire just isn't there).

Sorry to confuse you. The removal of DRL's was something that my Volvo dealer did while I was living in Germany. I was just using that as a reference as to what abilities the dealer has. I wanted to know if GM has a way of enabling or adding their own work around to separate the lights. I definitely DON'T want to disable the DRL's on the TourX. I love the drl design.

 

[Anaduff]

I've seen (somewhere) that the programming available to GM dealers & their tools (Tech II and the like) are 'region specific'--a lot like trying to play a region 3 DVD in the US. The BCM may be the same worldwide but the wiring harness & software isn't. Every one of the 7 plugs connecting to the BCM have multiple empty sockets where 'the good stuff' (defined as 'what you can't get in the US') could attach to.

I would love to hear from those members who shipped their Regal's to Europe to see how the dealers over there handled the required (as in tail lamps) conversions...

 

[Skynet]

Anaduff

Ok, so I've done some digging around and either can't find the correct connector or the colors are different for the front left and right turn signal wires. Also, I can't locate on the connector, the numbers you indicated. Here are some photos I've taken; can you help me identify the correct connector.







I'm not exactly sure what I'm looking at.
[/QUOTE]

______________________________

 

[Anaduff]

What I think you're looking at here is the HMI module (the NGI 2.5 box) and the radio module. The front turn signal wires come from the BCM module. On my 2019, that unit is located in front of the centre console (you have to fold down the liner on the left side of the passenger foot well). You're looking for a box that has 7 large cable connectors--all of a different colour. The connectors are numbered from left (towards the back) to right (headed towards the front) X1 through X7. The front right turn signal is on X4-pin 3 (green/violet wire), and the left turn signal is on X5-pin 2 (blue/white wire). Both wires are on the top row of there respective connectors. Hopefully the BCM is same in your slightly earlier model...

 

[Skynet]

What I think you're looking at here is the HMI module (the NGI 2.5 box) and the radio module. The front turn signal wires come from the BCM module. On my 2019, that unit is located in front of the centre console (you have to fold down the liner on the left side of the passenger foot well). You're looking for a box that has 7 large cable connectors--all of a different colour. The connectors are numbered from left (towards the back) to right (headed towards the front) X1 through X7. The front right turn signal is on X4-pin 3 (green/violet wire), and the left turn signal is on X5-pin 2 (blue/white wire). Both wires are on the top row of there respective connectors. Hopefully the BCM is same in your slightly earlier model...

View attachment 28515

Thanks. I'll look again in the morning. I was definitely looking in the wrong location. These pictures were taken from the right side of the passenger foot well, above the foot well lighting.

 

[Skynet]

Thanks to Annaduf, who helped provide the wiring diagrams for this task. I finally got the Euro tails properly connected on my Country/Sports Tourer project. I now have separate brake and amber turn signals.

 

[Anaduff]

Hope you remembered the last detail...

______________________________

 

[Skynet]

Hope you remembered the last detail...

View attachment 29307

I was much relieved when I was done. I was afraid I'd clip the wrong wire but all was good and the drinks better lol.

 

[94cruiser]

Good work!

With the stock US tail lights is there a "spot/socket" for a rear fog light?
That could be turned on/off with a switch in the cabin?

 

[Rhetoric]

Good work!

With the stock US tail lights is there a "spot/socket" for a rear fog light?
That could be turned on/off with a switch in the cabin?

There is a blank for it, but not something that would work by just drilling a hole from what I can see.

Anaduff has shared info that the lights are controlled by the BCM, so even if you have the right headlamp switch you would either need to run your own wiring or attempt to add more from the switch to the BCM. blah blah blah. That's a lot of work for a rear fog.

 

[toolmanAR]

There is a blank for it, but not something that would work by just drilling a hole from what I can see.

Anaduff has shared info that the lights are controlled by the BCM, so even if you have the right headlamp switch you would either need to run your own wiring or attempt to add more from the switch to the BCM. blah blah blah. That's a lot of work for a rear fog.

I don't know if it's that big a deal to make a rear fog work; just power and ground and a bulb socket, with +12V power running through a switch on the dash. Pick up power in the dash from one of the 12V power points (since I presume the rear fog will be an LED so it'll draw very little current), convert one of the dummy buttons to a functional two-position switch. No real reason to run the rear fog's operation through the BCM. Not the way an OEM would do it, but probably the best way to get a rear fog on a car where it's not really designed to exist.