I have just started using Gem's 340 as my daily driver, to which i must say I’m really enjoying. But I’ve just come across a bit of a problem. As it has the original radio i thought i would put a spare radio in i handling around, i bought a adapter plate off ebay and tonight pulled the old radio.
As there seemed to be no plug anywhere i cut the wires behind and had a spare strip of connector blocks started putting each cable into that to keep it safe as i was not going to put the new head unit in until the weekend. I didn't think of putting a multi meter across the connections as i could do that later. Anyway as i cut the last (Black thicker cable) i found to my delight the car has an alarm
There is a keyhole in the real wing of the car which we have never used and I have no idea on how this has been wired in. The alarm noise is the car horn and we've had no other problems. Do any of you have an idea how this may have been wired and (Just looked at the Haynes ) can anyone tell me the values of the cable colours before i try to test it and probably set the alarm off again.
The alarm you have there is a Volvo accessory - and the black wire you cut on removing the radio finds an earth via the radio - loss of this earth triggers the alarm.
Many moons ago I scanned my whole set of accessory fitting instructions and Aymat posted them in the Tech Resource section (look under "Blue leaflets").
You will find the instructions for your alarm there.
Incidentally - it's not just a switch on the rear wing - it's a fairly complex star wound resistor that has to be in circuit with the alarm both on and off!!
If you can't find answers in the instructions PM me as I have wiring diags (and quite a few spares) for the system.
I cant belive i missed the blue leaflet, i was trawling through them last night for a few other thinks. It must have been lack of sleep.
The question i have now then is if i put a new head unit in and rewire it to the new radio -ve...
Actually i'm going to stop there. I can be a bit flakey when comes to electrics without sitting down and working out what is wired to what properly. I know there are only three speaker wires and one looked like it had an inline fuse and then theres the two other wires, red which i presumed was +ve and then the black one. There is also a black earth.
Try getting to my age - you can't find anything (even bits bolted on).
The whole subject of ICE wiring on 300s is a bit of a minefield really - but as to the black alarm wire you can connect it to any part of the new radio that gives an earth (preferably on the set itself such that removal will trigger the alarm) i if you're lazy just earth it to the car (but it wouldn't then protect anything).
Originally, from the factory 300s weren't fitted with a radio (although none were sold without) so the loom connection was very simple - in the radio "box" was a 9 pin female socket containing two wires - a Green wire (12v+) originating at fuse 12 (also brake lamps and heater blower) and a Brown wire providing an earth. On the UK market three other positions were filled by speaker wires with a common return (later changed to four). This arrangement was suitable for the very simple ICE units supplied on early models. As the radios became more complex a number of adapters were introduced to suit specific radios (eg the Philips range from 86) and the number of speakers fitted (usually only two). Some later sets also required an extra (permanent) live 12v+ supply to hold up radio memory etc. and this generally was Red. Speaker wires were usually Brown/Black but I have seen Grey/Black, Grey/Red and Black/Yellow (especially if rear speakers were fitted) !!!
What you have on your car depends on age, what was fitted before, how much it's been changed, and probably what day of the week you look at it.
Best thing is to work out what you have on which wire ie. switched 12v, permanent 12v, earth, and speaker pairs and match them to what the new radio needs.
) can anyone tell me the values of the cable colours before i try to test it and probably set the alarm off again.