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[Kevin Wood]

Hi there,

Just a quick one. Does anyone happen to know the location of the trailer bulb failure sensor (p39) on a facelift and which pins need to be bridged to enable the brake light output on the trailer pre-wiring connector in the boot?

Just fitted a tow bar and everything bar the brake lights is sorted.

Cheers,

Kevin
  

[Andy B]

Hi there,

Just a quick one. Does anyone happen to know the location of the trailer bulb failure sensor (p39) on a facelift and which pins need to be bridged to enable the brake light output on the trailer pre-wiring connector in the boot?

Just fitted a tow bar and everything bar the brake lights is sorted.

Cheers,

Kevin
  

Above the driver's feet on a pre face lift car - can't say for the face lift though. I don't know the numbers but it's the two wires that are the same colour - black/yellow seems to ding a dong.

[Kevin Wood]

Many thanks. I remember seeing something that looked like an empty relay socket up there last week when I was meddling. I'll give it a try. Thinking about it, I've got the colours on the wiring diagram so I should be able to identify the pins.

Cheers,

Kevin

[Kevin Wood]

For the record it's not above the driver's feet on a facelift.

I tracked it down in the end and it's on a metal bracket to the left hand side of the glove compartment up under the passenger side of the dash. A real PITA to get to. I had to remove the heater vent and glove compartment to find it  

For anyone contemplating a tow bar install I'd recommend using the feed to the rear light cluster brake lights and forgetting about the signal in the prewired trailer connector. It makes for a slightly more messy installation in the back end, but saves having to mess about under the dash. It is the black and yellow wires, though. You'll find 2 of them going into the relay socket (along with a brown and a grey and black wire). Bridge the two black and yellow wires using 2 spade connectors with a short length of wire between them and leave the others disconnected.

Kevin

[Andy B]

Hi there,

Just a quick one. Does anyone happen to know the location of the trailer bulb failure sensor (p39) on a facelift and which pins need to be bridged to enable the brake light output on the trailer pre-wiring connector in the boot?

Just fitted a tow bar and everything bar the brake lights is sorted.

Cheers,

Kevin
  

Has anyone ever bought one of these? I'd like the part number please. Just been to the dealer to order one - in preparation for attaching my mobile road block!   - and we couldn't find it.    I seem to remember having problems finding the Senator's equivalant yonks back.

[Kevin Wood]

I'd be interested if you do find out. I believe there's a flasher unit with an extra output for the trailer bulb on the dash too but haven't really got round to investigating. It would be nice to get rid of the annoying buzzer and have a visual indicator warning instead.

Kevin

[Andy B]

I'd be interested if you do find out. I believe there's a flasher unit with an extra output for the trailer bulb on the dash too but haven't really got round to investigating. It would be nice to get rid of the annoying buzzer and have a visual indicator warning instead.

Kevin

I'll let you know.
The dash lamp is easy. You just need to swap your 3 pin flasher relay for a four pin available at Halfords or you local towbar fitting outfit, and a lamp in the dash. Beware though that the two I have bought recently have been a lot noisier than the original. The first I bought at Halfords and put the extra noise down to it being a cheap generic copy so I bought a 'proper' Hella relay and that was just as bad. The reply I got from Hella when I questioned the extra noise was:
These relay types are built in this way to aid bulb failure indication.To make it a little less noisy you could insulate it by using pipe lagging type foam and wrapping tape around it.  :-/  :-/  :-/
So much for a high tech solution!  

[michael_de]

hi i fit towbars at work quite often and we use a six way bulb failure by-pass relay which is very reliable i have a couple spare with switchable buzzer ill send you one if you want

cheers

[Andy B]

hi i fit towbars at work quite often and we use a six way bulb failure by-pass relay which is very reliable i have a couple spare with switchable buzzer ill send you one if you want

cheers

What exactly do these relays do? As I understand it they are fitted to avoid upsetting the car's bulb failure devices, especially of more modern cars that use Can-Bus wiring ...... but there again I could be way off mark!  :-?  

[Kevin Wood]

What exactly do these relays do?

I guess there are two functions and some do one or other, a few do both.

1) There is a legal requirement to have an indication to the driver when the trailer indicators are working. There is a bulb in the dash to indicate this but neither the bulb nor the flasher unit with the extra current sensor is fitted without a factory towbar. Most aftermarket towbar fitting places don't bother with this, and take their feeds from the rear light cluster wiring. Some will wire a warning lamp on the dash, but since this requires running an additional cable to the front of the car, most don't bother so they fit a current sensing device in the boot with an audible warning to indicate when the trailer lights are working. So these devices merely sense current flowing to one or other of the trailer indicators and make an annoying beeping noise to alert the driver.  

2) Where bulb failure sensors are fitted, the extra load from the trailer lights will at best cause this not to function when towing. At worst, they may overload the circuits supplying the light clusters. If you want to pick up the feeds from the light clusters you need to put a relay in to switch the trailer lights and this removes the extra load from the bulb failure sensor in the car, since these circuits are now only switching the relay, not feeding the trailer bulbs themselves.

The omega has a connector pre-wired for towbar electrics and can accommodate an extra bulb failure sensor for the brake lights, which displays a warning on the MID but again this is not fitted unless a factory towbar is fitted.

Thanks, michael_de for the offer. I've already got an audible warning in the back, though, and for the occasional towing I do, it's probably not worth disturbing the dash to get the light working. If I ever have to remove the dash for another reason I'll probably have a go..

Cheers,

Kevin

[Andy B]

What exactly do these relays do?

I guess there are two functions and some do one or other, a few do both.

1) There is a legal requirement to have an indication to the driver when the trailer indicators are working. There is a bulb in the dash to indicate this but neither the bulb nor the flasher unit with the extra current sensor is fitted without a factory towbar. Most aftermarket towbar fitting places don't bother with this, and take their feeds from the rear light cluster wiring. Some will wire a warning lamp on the dash, but since this requires running an additional cable to the front of the car, most don't bother so they fit a current sensing device in the boot with an audible warning to indicate when the trailer lights are working. So these devices merely sense current flowing to one or other of the trailer indicators and make an annoying beeping noise to alert the driver.  .

Just plug the 4 pin relay inplace of the original 3 pin, put a lamp in the dash & hey presto! No extra wiring required

2) Where bulb failure sensors are fitted, the extra load from the trailer lights will at best cause this not to function when towing. At worst, they may overload the circuits supplying the light clusters. If you want to pick up the feeds from the light clusters you need to put a relay in to switch the trailer lights and this removes the extra load from the bulb failure sensor in the car, since these circuits are now only switching the relay, not feeding the trailer bulbs themselves

The omega has a connector pre-wired for towbar electrics and can accommodate an extra bulb failure sensor for the brake lights, which displays a warning on the MID but again this is not fitted unless a factory towbar is fitted.

Thanks, michael_de for the offer. I've already got an audible warning in the back, though, and for the occasional towing I do, it's probably not worth disturbing the dash to get the light working. If I ever have to remove the dash for another reason I'll probably have a go..

Cheers,

Kevin

I've just plugged my trailer 12N socket into the factory fitted plug in the boot and all my trailer lighting works, although obviously I've no lamp failure sensing on tail lamps. I gave in with lamp failure module & Astra loom that I had. I towed a lot with my previous Senator which was wired up in a similar fashion and didn't have any problems with lamp failure sensing. (I'll introduce a duff lamp with the trailer plugged in and see what happens  )

[Kevin Wood]

Just plug the 4 pin relay inplace of the original 3 pin, put a lamp in the dash & hey presto! No extra wiring required

Yeah, sorry to go over all of that again. Skimmed the thread and forgot we'd already been there  

I've just plugged my trailer 12N socket into the factory fitted plug in the boot and all my trailer lighting works

Yep. There's no need to feed them through relays on an Omega IMHO. The indicator and tail light circuits cope with the extra load and the brake light is separate wiring from the switch via the jumpered bulb failure sensor anyway.

TBH, I think bulb failure sensing on a trailer is pretty redundant anyway. I check the lamps on a trailer before every journey with one. How many people ever check the rear lights on their car?

It's just nice to get some confirmation that the 12N plug hasn't pulled out of the socket, which has happened to me once or twice!



One thing that did occur to me... The trailer brake light failure sensor seems to connect to the MID if I believe the wiring diagram.

How does the MID tell the difference between no trailer hooked up and a trailer hooked up with duff brake lamps?

Kevin

[Andy B]

.......

One thing that did occur to me... The trailer brake light failure sensor seems to connect to the MID if I believe the wiring diagram.

How does the MID tell the difference between no trailer hooked up and a trailer hooked up with duff brake lamps?

Kevin

I'll find out when my trailer lamp check arrives from the Father land next week.

Re the trailer check. I check lamps before a journey (SWMBO does while I do the the neccessary in the car   ), but on one particular journey, when I had the Senator, the brake light check kept coming on. Everything checked OK while we were stationary but on the move it would throw up a fault. I'd switch off and cancel it and everything would be OK for a while. The problem was a dodgy connection in the plug, which would/could possible have gone un-noticed without a check module.

[Andy B]

......
Has anyone ever bought one of these? I'd like the part number please. Just been to the dealer to order one - in preparation for attaching my mobile road block!   - and we couldn't find it.  ....

Just in case anyone wants the number it's [size=16]90463123[/size]
It took a couple of weeks to arrive though, but it's now fitted & tested.  

[Wazz]

Kevin you mentioned a wiring diagram for the Omega, I have a 2003 dti model any chance of a copy? Been looking everywhere for info on these cars, but a pain seeing as Haynes don’t do a manual for the later models.

Thanks

Waz