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Discussion Starter #1
Hoping someone has a Sky factory manual and can send me the schematic for the rear lights. I have the OEM manual for the Solstice but of course those cars only have a single bulb in the rear, and I need to know how they are wired from the BCM on the Sky. Trying to see if there's a nice way to fit the Opel GT lights and have the turn signal flash as appropriate without changing any wiring, basically flashing in the Opel GT BCM software or something.

Thanks in advance,
 

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This sounds wrong as I write it: Are you attempting to install Opel tail light assemblies into a Solstice? If so, wiring is the least of your worries, as the body shapes are completely different.

I can post the actual diagrams later, but for now all you get (from me) is words. I also have no hands-on experience with the Opel lights, but someone else may be able to add the missing insight.

The "magic" of the Opel tal lights is in the wiring harnesses, and not the BCM, as far as I can tell.

The 2008 wiring diagrams for the Sky and Solstice appear to be identical from the BCM to two connectors at the back of the car.
The 2006 Solstice and 2007 Sky diagrams also agree, at least to the limit that I compared them.
  • X400 (IP Harness to Rear Lamp Harness) has four pins
    • BK Ground
    • BN Tail / License / Park
    • L-GN Backup
    • L-BU Stop
  • X408 (Chassis Harness to IP Body Harness) has eight pins
    • BK Ground
    • TN Left Wheel Speed
    • OG Low Ref
    • BN Right Wheel Speed
    • WH Low Ref
    • YE Left Stop / Turn
    • BN Tail
    • D-GN Right Stop / Turn
From these connectors the wiring is unique to each model, interconnecting between the connectors and the light assemblies.

I have no specific documentation for the Opel, and have never heard that any exists..
 

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Discussion Starter #3
Thanks, sorry if it wasn't clear. I have the service book for the 2007 Solstice, but I'm trying to put the Opel lights in my Sky. Years ago I ordered the service book for the Sky from the US and they sent me the Solstice book, and it was such a pain to send it back and try to exchange it I never bothered, figuring they were similar enough for my needs.

The schematics from the Solstice book show a double filament bulb with a single wire on C308/18/YE (stop/turn) for the high-intensity side of the bulb on the left side. Meaning that, it seems as if there is no way to fire the signal vs. the stop lamp separately [assuming the Sky is the same]. If you're saying in the schematic for the 2008 that it's the same for both cars, then I'm guessing on the Sky that one circuit is wired to both bulbs in the assembly.

As the Opel has one bulb for the signal/hazard and one for the stop lamp, it seems to me as if they would have run two circuits and reprogrammed the BCM to fire the the turn lamp and the stop lamp individually. But, it sounds like I might need to see the Opel book to know for sure.

If there aren't two circuits in the Sky and reprogramming isn't possible, then the next most straightforward solution seems to be to wire the high-intensity outputs of the left and right lamps to the center lamp circuit with a relay, and then to just run another wire to the rear lights for the signal bulbs and jumper them from the front indicator circuits. (Will there be a fast-blink then because the rear bulb will be "missing?" Ugh. I guess I need to think about it. Hopefully there are two circuits and software reprogramming will be possible.)

Or, better yet, if someone else has already done this and can tell me the easiest way to do it, I'm happy to hear it. 😁
 

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What are the differences in operation between the two (Sky vs Opel)?

When I installed the rear Opel lights onto my ‘07 Sky, I didn’t even think to worry about schematics, wiring differences and any changes that might occur. Didn’t even realize (apart from bulb difference because of the connector) that there was a difference.

Thought they were both interchangeable.
 

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That makes a lot more sense than what I was thinking, and I couldn't remember what you have. I regret not being able to post the diagram yet, but the value it will have is questionable at best.

@marlboromike has done this conversion, and has mentioned the unique harness needed, so i am hoping that he can add some actual knowledge.

Meanwhile i will speculate.

The connector for the sub-harness built into each tail light assembly has six pins, only three of which are used in the Sky: Ground, Tail, and Stop / Turn. You are correct that the two bulbs are jumpered by that harness. Significantly in my mind, the Stop / Turn wires to each bulb are different colors in that sub-harness, suggesting that they are separate circuits for the Opel. If you have the light assemblies you can confirm that. Are there four pins used in the connector?

Assuming they are split, it would be relatively simple to get a non-blinking Stop lamp by adding a wire from the CHMSL pin in X400 to one of the circuits in each tail light. You may then need a load resistor, like those used with LEDs, to eliminate the hyper-flash.
 

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Discussion Starter #6
Thanks for the input. Let's see what @marlboromike has to say about it then. If he actually has the signals working as intended and knows the parts I need, then I'll owe him a beer for sure.

For me this is about road legal compliance, not about the aesthetic of it, so I really need the indicator to flash yellow as intended. I actually prefer the look of the Sky lights.
 

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Thanks for the input. Let's see what @marlboromike has to say about it then. If he actually has the signals working as intended and knows the parts I need, then I'll owe him a beer for sure.

For me this is about road legal compliance, not about the aesthetic of it, so I really need the indicator to flash yellow as intended. I actually prefer the look of the Sky lights.
Opel lights are not legal technically speaking...they were never approved by the Dept of Transportation.....but all wiring schematics you need are in your search community option...just put in Opel tail lights...all information on wiring is there.
 

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Discussion Starter #8 (Edited)
Mike, where I live the Sky lights are the illegal ones. This is the only reason I have to switch them. 😁

I found some of the threads you are referring to, but it seems like the solution is the blunt option of just wiring the rear lights to the front ones, using the center light to trigger the brake lights, and putting in a resistor. I was hoping that there was some knowledge of how the Opel itself actually was delivered and if it could be "correctly" retrofit.

I can't believe that anyone would go through this pain just for the look of the lights. It's almost as mental as putting on those gigantic mirrors. 😁😉
 

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Discussion Starter #9
I'm convinced now that I'm the only person who is looking to undertake this modification and yet is completely unmotivated to do it.
 

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Are these the lights that you’re referring to? Or the valance reverse lights?

Because these are plug-and-play rear Opel lights on an ‘07 Saturn Sky.

 

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Discussion Starter #11
Those are the lights--the issue is that I need them to function exactly like on the Opel. Indicators flashing as appropriate and a solid red light when braking.

It seems like it's doable to wire the indicators to the front lamp circuit, use a relay to fire the brake lights from the center lamp, and use a resistor to keep the fast flash from happening, but I was really hoping there was a solution that was more factory "plug-and-play," as it were.
 

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Did your lights come with the electrical attachments to plug in light bulbs?

Also, what do you think is different in braking/lightning patterns between the Sky and Opel?

This could’ve been misinformation or confusion but when I bought my Opel lights, way back in ‘10, I was told that the Sky and Opel rear lightning patterns were the same (braking, turn signal, etc).

Like I said earlier, I’m confused because I just removed my original Sky lights, plugged the Opel lights in, and went on my merry way. Help me guys… what am I missing here?
 

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Those are the lights--the issue is that I need them to function exactly like on the Opel. Indicators flashing as appropriate and a solid red light when braking.

It seems like it's doable to wire the indicators to the front lamp circuit, use a relay to fire the brake lights from the center lamp, and use a resistor to keep the fast flash from happening, but I was really hoping there was a solution that was more factory "plug-and-play," as it were.
I have been thinking about this since you first posted, and i have a couple of new thoughts.

As you have found, the wiring done to use the Opel lights in the US isn't going to work for you.

I think, with the correct harness, you could get the wiring to be totally factory. The lower-half red light would be connected (through that harness) direct to the CHMSL connector for a solid light when braking, and the upper-half clear/amber would be connected to the existing stop / turn wiring for a flashing light when turning. The problem is that you would also have a solid amber when braking. At that point there is likely a different BCM program that is used for the Opel that would eliminate the amber light when braking.

You can accomplish the wiring by running a single wire from the L-BU (Stop) wire at X400 to the fourth pin on each of the Opel tail light connectors. I am guessing that is the correct pin for the brake lights, but you may have to switch some pins around. No relay is needed because you aren't trying to isolate anything. This would also be a good opportunity to switch the bulbs to LEDs, since the rake lights do not have current sensing issues.

As an alternative to trying to find a different program, with all of the problems that could cause, I would get into the wiring at the BCM. The front turn signals feed from (I think) X1, and the rears from (I think) X3. You can cut the rear signal wires and then splice them into the fronts. Depending on the wattage of the Opel turn signal bulb, you may or may not get hyper-flash. If you do, you can use the rear connections from X3 for the resistors. You just have to find a place to mount them so that their heat won't damage anything.
 

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I really do not understand the problem here...do not touch anything up front....no resistors....my Opel tail light...u put on the brake, both the amber and red light up....when u put your headlights on, the red go on. When u turn...the red light only. All it was was cutting one wire (cannot remember which) and vampired it to another.
 

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I really do not understand the problem here...do not touch anything up front....no resistors....my Opel tail light...u put on the brake, both the amber and red light up....when u put your headlights on, the red go on. When u turn...the red light only. All it was was cutting one wire (cannot remember which) and vampired it to another.
Mike, that was fine for you, but won't work for mastrjon32. He is trying to set the lights up to comply with the European spec. The amber (only) has to be the turn signal and the red (only) has to be the tail / stop signal.
 

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The AMBER light should only turn on when signaling turns, should NOT turn on when brake is applied.
Its been a long time I seen a schematic for these lights (my days of sequential turn signal) but I believe it’s a solid green wire in the tail light harness that controls the turning signal and that’s the one with its black ground that should go to your Amber light.
 

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The AMBER light should only turn on when signaling turns, should NOT turn on when brake is applied...........
Exactly. The problem is that the Sky does not have an existing wire at the rear of the car that is turn signal only.

The options that i can see are: 1) Reprogram the BCM, 2) Build a circuit that monitors both stop/turn wires and prevents them from both being on simultaneously, and 3) Splice the rear turns into the front turns at the BCM.
 

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Discussion Starter #18
I think, with the correct harness, you could get the wiring to be totally factory. The lower-half red light would be connected (through that harness) direct to the CHMSL connector for a solid light when braking, and the upper-half clear/amber would be connected to the existing stop / turn wiring for a flashing light when turning. The problem is that you would also have a solid amber when braking. At that point there is likely a different BCM program that is used for the Opel that would eliminate the amber light when braking.
Now you see what I was getting at with my original inquiry. 🍻 I was hoping that the Opel programming or harness would isolate the function of each lamp to braking/indicating, and I could easily swap that in...but it seems that it might not be so easy to find the information I need.

If I do use the CHMSL circuit with the original Sky harness to connect the left and right lamps, then I think I will use a relay just to be safe and protect the BCM. I'm not sure that the CHMSL circuit has enough current to power all three bulbs, which is part of the reason I wanted to see the original Opel wiring diagram. The other part, as you stated, is to keep the indicator from coming on during braking--worst case I can tap the front turn signal circuits at the BCM and reuse the wiring that previously went to the Sky lamps.

Mike, that was fine for you, but won't work for mastrjon32. He is trying to set the lights up to comply with the European spec. The amber (only) has to be the turn signal and the red (only) has to be the tail / stop signal.
Yes, exactly. The car will be thoroughly tested as part of the registration process, there is no way it can pass without the lamps working exactly as intended. Stop lamps only for stopping, indicators only for indicating.

(I also will need to tackle the [email protected]#ing rear fog light--which, in case you've never driven in Europe, you would know is required but is literally used by no one.)
 

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Discussion Starter #19
The real question here is--why didn't they just use the Opel style lamps for the US market? I know that some cars in the US come with yellow indicators. Seems like it's more effort, and thus less cost effective, to make two separate styles.

(Though in my opinion the Sky lamps do look better!)
 

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Exactly. The problem is that the Sky does not have an existing wire at the rear of the car that is turn signal only.

The options that i can see are: 1) Reprogram the BCM, 2) Build a circuit that monitors both stop/turn wires and prevents them from both being on simultaneously, and 3) Splice the rear turns into the front turns at the BCM.
John, For some reason I THINK the solid Green wire with its dedicated Black wire will work as a turn signal circuit, check my old diagram on "sequential turn signal"..
- Or -
Do you know if the BCM shut or breaks the circuit using the Ground-Black wire on the turn signal circuit?

Sequential Turn Signal Diagram.jpg
 
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