Towbar Electrics help

[markf497]

Looking for advice on wiring electrics for my towbar, I got a 2nd hand towbar from the breakers yard for my 2014 Insignia hatchback and fitted it today. The towbar came with 13 pin electrics and 7 way smart bypass relay ryder tf2218/7h smart logic and a ryder TF1170-3 super smart combi 30 amp.

I know that the car electrics are canbus and I don't want to connect the cables in the wrong place.
Where is the best place to tap into the lights for the smart bypass relay, I had the rear light clusters out when I removed the bumper to fit the towbar and the wires going to the lights seem to be very thin?

 

Any advice greatly appreciated.

[markf497]

Found this guide on towsures website has anyone used this with success or any problems?

 

https://www. towsure. com/fit_a_multiplex_bypass_relay

[Guest]

Brave man buying from a breakers yard, how do you know the donor car wasn’t involved in an accident where the towbar was compromised?

[markf497]

2 minutes ago, Grandpa Steve said:

Brave man buying from a breakers yard, how do you know the donor car wasn’t involved in an accident where the towbar was compromised?

It was a local breakers yard and car was front end damage the breakers yard removed the towbar for me to collect.

[Guest]

As long as you are happy it’s ok then that’s really all that matters ?

[hp100425ev]

Personally I would be looking for a dedicated wiring kit that plugs into the connection points that will be provided in the car, probably behind one of the side panels in the boot.

[markf497]

14 minutes ago, hp100425ev said:

Personally I would be looking for a dedicated wiring kit that plugs into the connection points that will be provided in the car, probably behind one of the side panels in the boot.

I had a look at the dedicated kit but you still need to run cables to the front of the car at the fusebox and splice into a couple of wires.

As I have these parts I was hoping to just use them.

[Guest]

Just connect the relays up to the existing lamps and you will be fine, it's not rocket science and assuming you have standard bulbs in the rear lights rather than LED there wont be any issues.

[AlwynMike]

^^ What he said.

 

Connect to rear light cluster. Hopefully without using Scotchlock's!!

The wires only sense the voltage going to each lamp. All the power for the caravan lights comes down the bypass relay power feed. Ensure it is "man" enough for the task.

 

[Paul_B]

One of the usual problems is with poor earth wire and earthing into the car, by doing it yourself you can do it properly.

[thebriars]

3 hours ago, markf497 said:

I had a look at the dedicated kit but you still need to run cables to the front of the car at the fusebox and splice into a couple of wires.

As I have these parts I was hoping to just use them.

You have to run cables from the front of the car to connect up correctly. If you are going to use a 13 pin connector and have all the connections for a caravan, ie fridge, battery charging, and possibly ATC, then you will need 3 cables running from the battery, two carrying 25amps and one carrying 15amps. There will be no positive supply in the boot capable of supplying that current.

2 hours ago, AJGalaxy2012 said:

Just connect the relays up to the existing lamps and you will be fine, it's not rocket science and assuming you have standard bulbs in the rear lights rather than LED there wont be any issues.

 

. ..and the power for the fridge, battery charging and possibly ATC?

[Paul_B]

1 minute ago, thebriars said:

You have to run cables from the front of the car to connect up correctly. If you are going to use a 13 pin connector and have all the connections for a caravan, ie fridge, battery charging, and possibly ATC, then you will need 3 cables running from the battery, two carrying 25amps and one carrying 15amps. There will be no positive supply in the boot capable of supplying that current.

 

One of the reasons I had mine fitted at a towbar centre, that and the reassurance of the warranty and that the cost wasn't excessive.

[markf497]

Thanks i'll tackle it next week when as i'm off for the week. There is a fuse box in the boot of the insignia i've just checked and at the top there are 2 heavy duty cables with 12v on them with the ignition off I should be able to take 12v from them.

[thebriars]

Just so long as the heavy duty cables have sufficient capacity for the extra 60+ amps you could be drawing. 60 amps is a lot of current. Its never that simple, and I would suggest if the dedicated kit runs the cables directly from the battery then you will need to do so also.   The alternative is blown main fuses, which are not very easy to source and in the meantime will have disabled your car, or worse, overheating cables and possibly a fire.

 

Is it really worth it?

Edited December 9, 2018 by thebriars

[Guest]

49 minutes ago, thebriars said:

Just so long as the heavy duty cables have sufficient capacity for the extra 60+ amps you could be drawing. 60 amps is a lot of current. Its never that simple, and I would suggest if the dedicated kit runs the cables directly from the battery then you will need to do so also.   The alternative is blown main fuses, which are not very easy to source and in the meantime will have disabled your car, or worse, overheating cables and possibly a fire.

 

Is it really worth it?

Highly unlikely to be drawing 60 amps. I only managed to get my battery charging up to 15 amps with my Sprinter as a tug by using pretty hefty cables. The fridge youre lucky to see 10 amps or thereabouts. Lighting 20w sidelights, 42w brake lights, 10w numberplate and 21w indicator totalling just under 8 amps so I make that 33 amps in specific circumstances, I suppose if it was foggy and you were reversing it could creep a little higher but generally not.

[Guest]

My fridge can drag 14amps.

[Tuningdrew]

Use the dedicated wiring harness.

 

[thebriars]

19 minutes ago, AJGalaxy2012 said:

Highly unlikely to be drawing 60 amps. I only managed to get my battery charging up to 15 amps with my Sprinter as a tug by using pretty hefty cables. The fridge youre lucky to see 10 amps or thereabouts. Lighting 20w sidelights, 42w brake lights, 10w numberplate and 21w indicator totalling just under 8 amps so I make that 33 amps in specific circumstances, I suppose if it was foggy and you were reversing it could creep a little higher but generally not.

I always wire up my own towbars and the vehicle specific wiring for my Mitsubishi stipulates one 25 amp circuit, one 20amp circuit and one 15 amp circuit as required by ISO 11446.

 

I'm afraid you are wrong with your adding up. Worst case scenario, 3 brake lights- don't forget high level light, could be 63w. Indicators x2 don't forget hazard lights. Side lights, don't forget all the side repeaters which may not be LEDs, my docs allow 52watts each side, fog light, there could be 2, therefore  42watts. All in all it adds up to nearly 300w, i. e. requiring a 25 amp wiring and fuse just for the trailer lighting.

 

Alko recommend 20 amp fuse for their ATC on pin 9. Again ISO 11446 recommends 20 amps for pin 9, and 15 amps for pin 10.

 

Remember while the OP may wire up for his current caravan, a change of caravan could see a higher current requirement without realising  the car wiring might also need to be changed too.

[macafee2]

5 hours ago, thebriars said:

You have to run cables from the front of the car to connect up correctly. If you are going to use a 13 pin connector and have all the connections for a caravan, ie fridge, battery charging, and possibly ATC, then you will need 3 cables running from the battery, two carrying 25amps and one carrying 15amps. There will be no positive supply in the boot capable of supplying that current.

 

. ..and the power for the fridge, battery charging and possibly ATC?

you sure that running all 3 wires direct from the battery is correct? Should the one for the fridge be a switched live? Ideally only live when the alternator is charging? Depending on how its wired there is a risk the car will use the caravans power to start.

Does ATC need a permanent live or a switched live?  Not having ATC I've no idea.

 

macafee2

Edited December 9, 2018 by macafee2

[AlwynMike]

Is there such a thing as dedicated wiring for fridge??

 

@macafee2 - ATC is operated from the permanent live (or what is billed as permanent live. Some dedicated wiring units  have this pin ignition controlled - so you can't check ATC without the engine running.)

 

The permanent live (fused at 20 amps) is for battery charging as well - controlled by the smart combi unit. This will only energise when the car is charging above a set voltage, which then supplies power to the fridge and caravan habitation relay, connecting the car battery/alternator to the van battery.

 

Should both the habitation and the combi relay fail closed, the 20 amp fuse will happily blow if car starter power is drawn.

 

And the earth returns can be made locally - no need to run wires to the battery for that.

Edited December 9, 2018 by AlwynMike
Earth

[markf497]

18 minutes ago, AlwynMike said:

Is there such a thing as dedicated wiring for fridge??

 

@macafee2 - ATC is operated from the permanent live (or what is billed as permanent live. Some dedicated wiring units  have this pin ignition controlled - so you can't check ATC without the engine running.)

 

The permanent live (fused at 20 amps) is for battery charging as well - controlled by the smart combi unit. This will only energise when the car is charging above a set voltage, which then supplies power to the fridge and caravan habitation relay, connecting the car battery/alternator to the van battery.

 

Should both the habitation and the combi relay fail closed, the 20 amp fuse will happily blow if car starter power is drawn.

 

And the earth returns can be made locally - no need to run wires to the battery for that.

I have some cable that I used for fitting my motor mover. I'll use that from the car battery its 6mm 53amp. I should have enough to run 2 cables.

 

Thanks for all the advice.

[Guest]

4 hours ago, matelodave said:

My fridge can drag 14amps.

Actual i. e. measured or theoretical? Most of the time the volts drop in the cables prevent it getting so high.

 

[Guest]

thats theoretical, it rated for 170watts

 

Actually my fridge only sees about 11. 3 volts when I'm driving so theres a big volt drop in the cabling somewhere.   Heres a plot of the both the van battery and fridge voltages taken earlier this year on a trip  (the fridge is the bottom one). the loggers weres strated witinn 10 secs of each other. One was connected across the  rear fridge terminal block and the other directly across the battery.

 

The towbar electrics are dedicated Ford manufactured and correctly installed by the dealer - on my car it's all plug & play so it's difficult to muck it up. The towing module is plugged directly into to a dedicated socket in the boot which also carries the fridge & battery supplies from the fuse box. There's a dedicated 40amp fuse which I guess is provides all the power to the towing functions via the module. I haven't investigated further to see where the volts drop is occuring as it's not everso easy to break into the wiring although I could put a clamp meter on the wiring at the back of the fridge.

Edited December 10, 2018 by matelodave

[Paul_B]

Different things use different power through the individual wires, but on return they use the earth and its quite often poor quality/sized wires or wire if they decide to wire the 2 together to save time.

 

 

[markf497]

Got it wired up today all tested ok to the 13 pin socket, I had found some info on the wire colours for each bulb but some didn't match so I used my multimeter on the connections at the lights. Just need to test on my caravan which has the 12s and 12n connectors I'll probably change it to a 13 pin connector rather than getting the adapter.  

 

Thanks for all the advice.