Tow bar electrics, need a permanent live on Autotrail Apache.

[RustyRuss]

Hi gang,

I have an Autotrail Apache 632 with Sargent electrical systems fitted, including an EM40 interface. I have bought an additional TPMS system from Tyrepal with monitors that allow me to inflate the tyres without removing the monitors, they’ll be fitted to the MoHo. I want to use the original valve monitors that I had on the MoHo on Kathryn’s Aygo when we use it as a Toad, this means I need to fit a signal booster at the rear of the MoHo to forward the Aygo’s readings to the screen on the dashboard of the MoHo.
The trouble is I want a 12volt live that only operates when the engine is running, I have opened up the 7 pin tow bar socket hoping to find such a live….. but it’s not connected! I’ve traced the wiring back to the vicinity of the EM40 but I’m perplexed about what terminal to connect to in the EM40 that will give me a live at the tow bar socket when the engine is on but will be disconnected at all other times.
Can you good people give me an indication of what to do please?
I’m an electrician but I’m not very familiar with vehicle electrics and don’t want to inadvertently bugger up any canbus systems connected via the EM40.

TIA!

Russ

 

[jockaneezer]

The only time I've known a live at a tow bar socket is when you have a "supplementary" socket fitted for caravanning, but that was with the old 7 pin jobbies ?

 

[RustyRuss]

That’s exactly what I want.

 

[1967bowesj]

Old sockets mate, the 7 pin black socket was not designed to have “power” just repeat signal inputs. You would need a 12s socket fitting, like this one

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[RustyRuss]

The system as fitted uses 7pin connectors. I want enough power to run a TPMS signal booster, it’s got a 1amp inline fuse in it at the moment so it isn’t pulling a lot of current.

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[GeoffnDee]

If it is any help , the www.sargentltd.co.uk support section has the towing and other connection information for the EM40 unit

 

[RustyRuss]

Does that mean I can connect the +ve terminal to Towing D+ and I’ll have power at the 7pin socket when the engine is running?

 

[dunnah01]

If you do go to the trouble of fitting a D+ feed you may as well go the whole hog modern 15 pin towing socket rather than the old skool 12N/12S type.

 

[icantremember]

All sounds a bit complicated... I have a similar Tyrepal system and just plug the booster into an internal 12v socket at the rear of the motorhome when towing.

 

[RustyRuss]

Dunnah I don’t want to change the 7pin plug in the engine bay of the car. I don’t want to change the socket on the back of the MoHo. All I want to know is can I have a live feed to the 7pin plug that I can use to run the signal booster that needs to be mounted in a location near the MoHo tow bar. But thanks for your input buddy.

Russ

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[RustyRuss]

All sounds a bit complicated... I have a similar Tyrepal system and just plug the booster into an internal 12v socket at the rear of the motorhome when towing.

I don’t think I have one of those. Just going out to check!!

Russ

 

[Derbyshire wanderer]

If fitting a new 12s system is not ideal then I would connect to the sidelight wiring and use them when driving.

 

[RustyRuss]

If fitting a new 12s system is not ideal then I would connect to the sidelight wiring and use them when driving.

That’s a good shout, but unfortunately if I run the side lights for more than 3 hours it flattens the battery on the Aygo!

Cheers though!
Russ

I don’t think I have one of those. Just going out to check!!

Russ

I’ve found a 12volt cigarette lighter type socket by the bed which I never knew existed! Who would have thought?! So that’s going to be my power source!

Thanks guys you have been a great help!!

Cheers!

Russ

 

[Derbyshire wanderer]

That’s a good shout, but unfortunately if I run the side lights for more than 3 hours it flattens the battery on the Aygo!

Don’t the toad lights work from the tow socket? I was thinking the motorhome lights via the tow socket.
Good that you have a power supply sorted now

 

[icantremember]

That’s a good shout, but unfortunately if I run the side lights for more than 3 hours it flattens the battery on the Aygo!

Cheers though!
Russ

I’ve found a 12volt cigarette lighter type socket by the bed which I never knew existed! Who would have thought?! So that’s going to be my power source!

Thanks guys you have been a great help!!

Cheers!

Russ

That should work fine ... in fact on occasions I have not plugged in the booster and the Tyrepal still connects with the toad.

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[Lenny HB]

That’s a good shout, but unfortunately if I run the side lights for more than 3 hours it flattens the battery on the Aygo!

Cheers though!
Russ

I’ve found a 12volt cigarette lighter type socket by the bed which I never knew existed! Who would have thought?! So that’s going to be my power source!

Thanks guys you have been a great help!!

Cheers!

Russ

But you have a Brit van, hab electrics will turn off with the engine running.

 

[RustyRuss]

But you have a Brit van, hab electrics will turn off with the engine running.

I thought that too Lenny, but the socket definitely works when the engine is running, I think it was retrofitted by the previous owner.

Russ