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Discussion Starter · #1 ·
Has anyone installed a 7 way bypass relay for towbar wiring by chance? Would be interested to know what wires you tapped into or if anyone has a wiring diagram they'd be willing to share I can go from there?

2018 Astra K Sports Tourer SRI Nav.

Thanks, Rich
 

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Do the MI not include a wiring diagram ? Have you not considered the dedicated wiring for the car Rich ? No programming is required on the K. and it's fairly easy to connect up, especially if you've got parking sensors installed. I can't tell from that pic if you have or not though.
 

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Discussion Starter · #3 ·
Do the MI not include a wiring diagram ? Have you not considered the dedicated wiring for the car Rich ? No programming is required on the K. and it's fairly easy to connect up, especially if you've got parking sensors installed. I can't tell from that pic if you have or not though.
Thanks for the reoly, the towbar I bought came with the relay and I'm happy enough to do the wiring so I was planning on using what I have instead of buying more stuff. Was really hoping for a wiring diagram but I can't find one online.
 

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I presume that's the Brink Vertically detachable 'bar ? I've got the Diagonal detachable on my ST and matched it with a 2nd-hand ECS dedicated wiring kit off the 'bay. I can see where you're coming from mate re: already having the kit available though. Does THIS help any at all ?

The one thing you need to be aware of (if you don't already know) is that I don't believe wiring up with a Bypass Relay will cut-out the parking sensors.
 

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Discussion Starter · #6 ·
I presume that's the Brink Vertically detachable 'bar ? I've got the Diagonal detachable on my ST and matched it with a 2nd-hand ECS dedicated wiring kit off the 'bay. I can see where you're coming from mate re: already having the kit available though. Does THIS help any at all ?

The one thing you need to be aware of (if you don't already know) is that I don't believe wiring up with a Bypass Relay will cut-out the parking sensors.
Thanks very much for the link, I do have the same thing already for the unit I have but it's the thought that counts 👍😊
Yeah it's the brink detachable, bought it so I could easily detach and not have to worry about the sensors kicking off 24/7. When towing I have a factory dash switch which can manually turn off the sensors so not too much to worry about on that front for how much towing I actually plan to do.
I reluctantly bought the Haynes manual to get some wiring diagrams which luckily they do include (I read a lot of bad reviews regarding the content) so I should be able to make a start on it soon. Thanks again. Rich
 

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I reluctantly bought the Haynes manual to get some wiring diagrams which luckily they do include (I read a lot of bad reviews regarding the content) so I should be able to make a start on it soon. Thanks again. Rich
You'll have to give us some feedback on the Haynes manual Rich. Redman mentioned it here a while ago not long after it appeared online but I'm not sure if he actually took the plunge or not.

And let us know how the wiring went :)
 

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Discussion Starter · #8 ·
Will do, just a quick scan shows it to be a bit vague on most stuff although the wiring diagram I needed was there so that helps me out. If the wiring will work with the relay relatively simply I'll do a write up on what wires to connect to, if not I'll be just ordering a dedicated wiring system and call it done.
 

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Discussion Starter · #9 ·
You'll have to give us some feedback on the Haynes manual Rich. Redman mentioned it here a while ago not long after it appeared online but I'm not sure if he actually took the plunge or not.

And let us know how the wiring went :)
Wiring is in and all is working as it should.
The Haynes manual paid for itself in my opinion for the wiring diagrams I needed, I'm a bit disappointed how they arrange the diagrams, you have to scroll across and up and down, they aren't willing to give you the entire diagram on one screen. I'm sure this is to stop people from sharing the info online.
 

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Discussion Starter · #10 ·
Wiring is in and all is working as it should.
The Haynes manual paid for itself in my opinion for the wiring diagrams I needed, I'm a bit disappointed how they arrange the diagrams, you have to scroll across and up and down, they aren't willing to give you the entire diagram on one screen. I'm sure this is to stop people from sharing the info online.
Towbar Wiring Instructions for 2018 Astra K Sports Tourer SRI Nav using universal 7 way bypass relay

I have provided this information because I couldn't find any info regarding universal towbar wiring relays. Please note that these instructions are based on my personal experience on my car, you are responsible for any work you do to your own vehicle and you do so at your own risk.

My model uses the same wire for the tail and brake light on the outside lights(variable resistance or voltage I assume) so I decided to use the number plate lamp wire for tail lights and centre brake light wire for brake lights to get around this.

Remove centre boot plastic moulding
Remove courtesy light housing
Unclip left side panel
Remove connector to cigarette lighter
Remove left side panel

Find these wires in the loom on left side:
Number plate light wire - green/yellow
Centre brake light wire - violet/white
Fog light wire - yellow/grey
Left indicator wire - blue/white

It is a good idea test the wires before going any further. I use a sewing needle to gently pierce the insulation and use a voltmeter to test that you've found the correct wire.

For the right indicator bulb gain access to the right side compartment and find the blue/violet wire. You'll need to run a wire from this to the relay. This is the only wire that i ran from this side of the car, everything else stays on the left side.

Now you've located all of the wires use scotch locks to fasten them to the corresponding wires on the relay(see diagram). All of the wires provided on the relay were long enough to reach the left side, I add to run extra wire to the right side for the indicator.

Then hook up your trailer socket wires to the relay(see diagram).

Extend both white wires and attach to the upper left earth point(10mm nut) just behind the rear seat or find another suitable earth point of your choosing.

Finally, run a 12v line to the relay. This can be hooked up however you like, I chose to use the cigarette lighter socket for my setup. I placed the inline fuse and relay in the left side access compartment for ease of access.

After checking all connections you can install the fuse and hook up your trailer or light board to test your wiring.

Good luck and shout out to Shaky for helping yesterday. Rich

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My model uses the same wire for the tail and brake light on the outside lights(variable resistance or voltage I assume) so I decided to use the number plate lamp wire for tail lights and centre brake light wire for brake lights to get around this.
Hi Rich. All the K models (apart from those with LED tail-lights) use single filament bulbs for Stop/Tail functions as they are controlled using PWM (Pulse Width Modulation) signals from the BCM. I always thought smart bypass relays (as I believe yours is) took account of this. Looking at the wiring instructions, (never done one so could be COMPLETELY wrong here :ROFLMAO:) I would say that in the K's situation, you would just leave the Brown & Black wires from the relay to the car disconnected and just connect the red wire from the relay to the Tail-light feed ?

Nice write-up all the same though. Good quality pictures and comprehensive instructions (y)
 
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Discussion Starter · #12 ·
Hi Rich. All the K models (apart from those with LED tail-lights) use single filament bulbs for Stop/Tail functions as they are controlled using PWM (Pulse Width Modulation) signals from the BCM. I always thought smart bypass relays (as I believe yours is) took account of this. Looking at the wiring instructions, (never done one so could be COMPLETELY wrong here :ROFLMAO:) I would say that in the K's situation, you would just leave the Brown & Black wires from the relay to the car disconnected and just connect the red wire from the relay to the Tail-light feed ?
You could be completely right but I'm happy knowing that it's wired as basic as can be. Just thought I'd share my experience, took about three hours from start to finish. If had to do it again in same vehicle would be half that.
 

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Not having to remove any of the clipped-in trim panels is an obvious bonus.........hate that with a vengeance :mad:.
 
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