I have an issue whereby connecting a bike rack the electrics failed to work, specifically lights, indicators didn’t replicate on the rack, with engine and running (or not).

 

I purchased an electrics test tool and that shows that the electrics on the car is working, LED test lights all display ok.

 

So wondering why the hook up electrics wouldn’t have worked on the rack?

 

Is there anything extra required to enable?

 

On my previous cars it was always just “plug and play”.

 

Thank you 

Hi

 

If you have simply paralleled up the trailer lights to the car's lights as used to be done years ago, the extra current load (if the trailer uses ordinary filament bulbs) will upset the bulb failure monitoring part of the CANbus system.

 

You either need a dedicated wiring kit, or something that uses relays with low current coils, the extra current of the coils isn't enough to upset things. 

 

Alternatively, if the bike rack lights are all LEDs,  their low current might mean that the simple paralleling approach will work.

Would a LED trailer board and bypass/remove the rack lights suffice?

Hi

 

I am fairly confident that an LED trailer board would work, but cannot guarantee it.  ideally you could find a retailer that will let you try before you buy.

14 hours ago, Flatjack said:

I have an issue whereby connecting a bike rack the electrics failed to work, specifically lights, indicators didn’t replicate on the rack, with engine and running (or not).

Was the tow-bar and electrics fitted when car was built or later?

12 hours ago, Austin 7 said:

Hi

 

If you have simply paralleled up the trailer lights to the car's lights as used to be done years ago, the extra current load (if the trailer uses ordinary filament bulbs) will upset the bulb failure monitoring part of the CANbus system.

 

You either need a dedicated wiring kit, or something that uses relays with low current coils, the extra current of the coils isn't enough to upset things. 

 

Alternatively, if the bike rack lights are all LEDs,  their low current might mean that the simple paralleling approach will work.

100% agree with all that, there is a further issue that using a correct low impedance by pass relay and a trailer board with LEDS then the module will not recognise that they are fitted and will not sound the confirmation buzzer, whether it would then disconnect the output I don't know.

 

I would stick to incandescent bulbs unless its the factory set up and programmed for LED bulbs in which case a normal trailer socket tester will not work on either the socket or the trailer.

Its high time that the only cable cores in a trailer connections become a decent conductor size live and neutral to power everything including caravan fridges etc, no second cable.

 

All the lighting commands would be transmitted wirelessly and of course use LED bulbs.

 

It will require a new EU legislation but it will come, there are far too many dodgy connections on the current set up and too many long cable cores which are getting too small in cross sectional area.

Actually the switching commands could be along the 12V supply cables courant porteur en ligne in my country, possibly DLAM in English?

1 hour ago, J.R. said:

I would stick to incandescent bulbs unless its the factory set up and programmed for LED bulbs in which case a normal trailer socket tester will not work on either the socket or the trailer.

 

Some 13-pin trailer socket testers are known not to work with CANBUS-equipped vehicles anyway, see: https://www.gov.uk/government/publications/mot-special-notice-01-19-towbar-electrical-socket-test-tools-diesel-smoke-meters-and-annual-training-and-assessments/mot-special-notice-01-19-towbar-electrical-socket-test-tools-diesel-smoke-meters-and-annual-training-and-assessments  Basically, the testing devices concerned use LEDs and, as I think we all know by now, the CANBUS will throw a fault if it finds an LED bulb where it's expecting an incandescent.

 

My Yeti was failed for this very reason in 2020.  I took it back to the testing station with my towbar-mounted bike carrier fitted and connected up, and they passed it.  Which wasn't a huge surprise, since it worked fine.

 

I've read elsewhere that fitting a 13-pin to 7-pin adaptor to the trailer socket on the car is another way to avoid arguments with MoT testers about this.  Apparently the test procedure for a 7-pin socket is purely visual - looking for damage, corrosion etc - and they aren't allowed to remove the adaptor to check the connectivity of the 13-pin socket it's plugged in to.  Which I'm sure makes perfect sense...to someone.

 

If they struggle to make a device that works properly when it's just testing the supply of current to individual lights*, I wouldn't hold out a great deal of hope for them being able to come up with a device that can test a digital solution as proposed by J.R.

 

*  I suspect a good number of us on this forum could construct a functional test device at home with a hour or so's work and a few pounds' worth of materials.  Yet apparently it's beyond the wit of the great global automotive industry 🙄

Edited 20 June, 20223 yr by ejstubbs
Wibbling on

The 7 pin tester plugged into the car works fine, all LEDs light up correctly.

 

However the Bike rack electrics don't.

 

But the same Bike rack on a different car works fine....

 

 

Was the tow-bar and electrics fitted when car was built or later?

I don't know. 

 

Its not a Skoda branded tow-bar.

 

3 hours ago, Flatjack said:

I don't know. 

 

Its not a Skoda branded tow-bar.

 

Skoda fit Westfalia.

11 hours ago, ejstubbs said:

as I think we all know by now, the CANBUS will throw a fault if it finds an LED bulb where it's expecting an incandescent.

 

I do hope that is not "all of us" as that would make me the only person to know that the oft repeated phrases using Canbus in relation to lighting circuits should never contain the term.

 

The canbus does not monitor bulbs, a control module will do so if the vehicle has bulb monitoring, it may be called various names like body control module, comfort control module etc even by the same manufacturer, these modules communicate with the main ECU and other control modules via the Canbus network, it does not "throw errors" but may communicate the information to other modules whose outputs may be modified accordingly.

Edited 20 June, 20223 yr by J.R.

Happy to close this issue!

 

Found that the 7-13 adapter was faulty/inconsistent.

 

Replaced with new one and working now.

 

Many thanks to all the suggestions.