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-   -   Loss of power at permanent live and ignition live pins (https://www.volvoforums.org.uk/showthread.php?t=294734)

Simon J May 13th, 2019 21:02

Loss of power at permanent live and ignition live pins
 
My V50 has a 13 pin Volvo cable harness complete with trailer module and software update. My trailer has just a seven pin 12N plug so I've been using an adapter and all has worked fine. But I had also checked that pin 9 (permanent live) and pin 10 (ignition switched live) worked as I planned to use them in due course.

I have now started on converting the trailer to 13 pin and made up a new cable with a Menber 13 pin plug and proper 8x1.5mm2 and 5x2.5mm2 cable. Before wiring it into the junction box on the trailer I connected it to the socket on the car just to make sure everything worked and ... no power to either pin 9 or pin 10. As I had removed the old 7 pin plug and wiring, I checked the light circuits using a multi meter and all seem to be fine, apart from pins 9 and 10. I checked the continuity of the grey and orange wires (pins 10 and 9 respectively) from the pin to the end of the cable and they are fine. I likewise double checked that I had them in the correct position, which I have. I also checked the socket and it isn't live on pins 9 and 10.

I checked the 40amp fuse and it seems to be fine.

So where have I lost the power and how to fix it?

SwissXC90 May 13th, 2019 21:09

Check if brake lights and tail lights work properly, and turn off when they should

If you transposed the pin numbers, you would be transposing tail light with permanent power, and brake with switched ignition

Check also you have a proper ground on pins 3, 11 and 13.

Otherwise, check the fuses in the REM. the ignition feed and permanent feed are fused.

Simon J May 13th, 2019 21:16

Many thanks for this speedy reply.

I'll check the pins again (I did check the three earths for continuity with the car frame) but I'm pretty certain I had got them right. Most diagrams you get, such as the one with the Menber plug, show the pins from the front, not the view when you're wiring them so I was very particular about having the correct view printed on a card in front of me while I did the connections. Plus, I also checked the numbers inscribed on the terminals.

The fuses you refer to sound like the likely culprits but what, and where, is the REM? And what might have caused them to blow since they haven't been used.

Clan May 13th, 2019 21:22

Quote:

Originally Posted by Simon J (Post 2520420)
My V50 has a 13 pin Volvo cable harness complete with trailer module and software update. My trailer has just a seven pin 12N plug so I've been using an adapter and all has worked fine. But I had also checked that pin 9 (permanent live) and pin 10 (ignition switched live) worked as I planned to use them in due course.

I have now started on converting the trailer to 13 pin and made up a new cable with a Menber 13 pin plug and proper 8x1.5mm2 and 5x2.5mm2 cable. Before wiring it into the junction box on the trailer I connected it to the socket on the car just to make sure everything worked and ... no power to either pin 9 or pin 10. As I had removed the old 7 pin plug and wiring, I checked the light circuits using a multi meter and all seem to be fine, apart from pins 9 and 10. I checked the continuity of the grey and orange wires (pins 10 and 9 respectively) from the pin to the end of the cable and they are fine. I likewise double checked that I had them in the correct position, which I have. I also checked the socket and it isn't live on pins 9 and 10.

I checked the 40amp fuse and it seems to be fine.

So where have I lost the power and how to fix it?

Have the pins 9 and 10 ever worked ? did you fit a NEW trailer module and have the software loaded ?

Simon J May 13th, 2019 21:25

Pins 9 and 10 were checked and working when the towbar was fitted. It was a new Volvo cable harness and trailer module and the software update was done by my local Volvo dealer. I also had checked, in particular, pin 10 as I was expecting it to only go live once the engine was running but it was live as soon as the ignition was switched on. But that's another saga!

Clan May 13th, 2019 22:14

Quote:

Originally Posted by Simon J (Post 2520429)
Pins 9 and 10 were checked and working when the towbar was fitted. It was a new Volvo cable harness and trailer module and the software update was done by my local Volvo dealer. I also had checked, in particular, pin 10 as I was expecting it to only go live once the engine was running but it was live as soon as the ignition was switched on. But that's another saga!

Pin 9 is fed directly from fuse 77 in the CEM under the glove box,

Pin 10 is fed directly from the trailer module which gets it's feed from Fuse 14 in the engine compartment fuse box ... The red wire going into the trailer module should be live all the time .

Simon J May 13th, 2019 22:22

Fuse 14 seems to be ok. Getting at the trailer module to check the red wire is a pain! I’ll check fuse 77 in the morning but what would have made it blow?

Simon J May 14th, 2019 19:41

Well, after grovelling in the passenger footwell to get at the fuse box located there it turns out that fuse 77 was blown. Now the question is, why? It’s only a 15 amp one so what does it supply?

OK, I replaced fuse 77 and that restored power to pin 9 (permanent live) but pin 10 is still dead. I double checked fuse 14 and it is fine.

What next?

Clan May 14th, 2019 20:35

Quote:

Originally Posted by Simon J (Post 2520581)
Well, after grovelling in the passenger footwell to get at the fuse box located there it turns out that fuse 77 was blown. Now the question is, why? It’s only a 15 amp one so what does it supply?

It supplys Pin 9 and also the rear 12v Power outlet socket ( if you have one ) and 15 A is the correct fuse .

Simon J May 14th, 2019 20:57

As I said above, with replacing fuse 77 I now have pin 9 (permanent live) working but still nothing at pin 10 even though fuse 14 is ok.

Where do I look next?


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