GreenLove

GreenLove

New Member
Been reading some threads about how to install a 10A stereo into my 1992 110 but am a little confused about the wiring.

Have read that you can somehow splice into the ciggie lighter wires. Now I've just replaced my lighter with one that works (currently runs off a 7.5A fuse.) There are two wires running into the back of the lighter, one black, one green.

Questions:


  1. Is the black wire earth?
  2. Is the green wire ignition live?
  3. Do I actually need a 12V constant feed to run the stereo, and if so, where would I find one?
  4. The stereo has a 10A fuse in the back of it, and the lighter currently runs off a 7.5A fuse in the fuse box. So, what amp fuse should I put in the fuse box to accommodate both devices running simultaneously?
  5. How exactly do I use the lighter wires to power the stereo? Do I splice the necessary wires just before they connect to back of the lighter or do I need to run separate wires for the stereo from the lighter fuse? I've only just started to learn about electrics and wiring so often find myself bumping into head scratching queries at this stage of my education.
Sorry for the bunch of questions, but I don't want to start a fire whilst listening to Credence, if I can help it.


Thanks
 
You need to get a multimeter and test the wires to see what they are.

As your stereo has got a 10a fuse in the back you could wire it straight to the battery. The Stereo installation manual should tell you what to connect where.
 
Flet said:
You need to get a multimeter and test the wires to see what they are.

As your stereo has got a 10a fuse in the back you could wire it straight to the battery. The Stereo installation manual should tell you what to connect where.
Click to expand...

I have a multimeter. So with regards to testing the wires, what do I need to test?

Flet said:
The Stereo installation manual should tell you what to connect where.
Click to expand...

Yes, I've already labelled all the stereo wires ready for installation. It's just a matter of knowing how to wire up to the ignition, constant 12v and earth.
 
Black wire will be earth, green (in all liklihood) an ignition switched live.

Reason for needing a permanent feed to the stereo as long as a switched one, is so that it doesn't forget the preset radio stations when it's turned off, and you don't accidentally leave it on when you leave the car.

If splicing into the ciggie green wire, you can use a scotch lock connector before the wire goes into the ciggie lighter, or cut the wire and join with a small connector block.

Re: fuse, do not replace the existing one with a higher one - it's done to protect the existing wiring. Should be ok at 7.5 amps.

Re: testing the wiring, your multimeter will probably have a dial to select different functions - set to the dc voltage range that covers 12v (probablky soemthing like 0 - 20v on the dial). Put the black prong to an earth point on the body (the screws that hold the fuse board on are normally good) and use the red prong to find a wire/connector that is live when the ignition is on, but is dead when it's off
 
Last edited:
Station House said:
Black wire will be earth, green (in all liklihood) and ignition switch live.

you can use a scotch lock connector before the wire goes into the ciggie lighter
Click to expand...

Great! Just received 50 of these connectors through the post.

Station House said:
Re: fuse, do not replace the existing one with a higher one - it's done to protect the existing wiring. Should be ok at 7.5 amps.
Click to expand...

So, do you think it'll be ok to have the stereo and lighter turned on at the same time? I'm by no means a competent electrician but I would have thought that the lighter would draw 5 ish amps and the stereo 7 ish amps during operation, which combined may exceed the wire amperage and/or blow the fuse?

Station House said:
Put the black prong to an earth point on the body (the screws that hold the fuse board on are normally good) and use the red prong to find a wire/connector that is live when the ignition is on, but is dead when it's off
Click to expand...

Will do. I've been trying to trace a reverse light problem so have used a multimeter in this way before.

Incidentally, thanks for info Station. Clear and informative as always :D
 
If it was me, id run new wires on a seperate fuse.

Permenant Live from battery with inline 10A fuse.
Ground to nearest bolt/screw

I created a new Fused ignition live for a multiude of uses.
take a feed from the Cigi ignition live to a 20A relay fed by a perm live from battery (fused)
Then feed the output from the relay into a 4 way fuse holder.
images



This means a can run seperate ignition lives on individual fuses to whatever needs them.
CD Player
CB Radio
etc etc



Might be abit over kill if yu dont plan on adding any additional equipment, but is the only way to know exactly the ratings of cables, fuses, circuits etc.
 
Last edited:
Pleasure

the current drawn by the car radio depends on how loud you have it - unless you're using the ciggie lighter socket to power something else which draws a reasonable current, I'm as sure as I can be without testing that it will be fine.

Other options if you're worried are:

1) As Sam suggests, run a dedicated wire with an inline fuse direct from the battery - you can buy round connectors that the battery clamp screws can go through to make fixing easy if you don't want to 'wrap/trap' the wires around the bolt head - can send a link if required

2) Find a more 'chunky' live feed from the ignition switch

3) Should be a fuse in the board behind the gear stick marked for 'radio' - need to unscrew board to connect from behind

take your time, make sure everything is well insulated and it will be fine.
 
Last edited:
BearDy89 said:
If it was me, id run new wires on a seperate fuse.

Permenant Live from battery with inline 10A fuse.
Ground to nearest bolt/screw

I created a new Fused ignition live for a multiude of uses.
take a feed from the Cigi ignition live to a 20A relay fed by a perm live from battery (fused)
Then feed the output from the relay into a 4 way fuse holder.
images



This means a can run seperate ignition lives on individual fuses to whatever needs them.
CD Player
CB Radio
etc etc



Might be abit over kill if yu dont plan on adding any additional equipment, but is the only way to know exactly the ratings of cables, fuses, circuits etc.
Click to expand...

Ah, I might be getting my wires crossed here. I thought the ignition live provided the power needed for the stereo to function, but perhaps it just acts like a switch telling the stereo that it's ok to operate (the actual power being taken from the permenant live.) In other words, if I didn't have a permenant live connected but only the ignition live connected to the stereo, then the stereo wouldn't function at all. Is this correct?
 
Sam's suggestion is a smart one if you want to run a dedicated power supply to control a number of things that are ignition controlled - it basically takes a dedicated live feed using chunky cable from the battery, but uses a relay (powered by the ciggie lighter ignition controlled feed) to turn the circuit on or off.

My suggestion of just taking a live feed from the battery with an in line fuse just gives you a permanent live to use.

The permanent live to the radio is all about it retaining memory presets (radio setting, bass, treble, balance) etc when it is turned off.

Honestly don't know if not having the permanent live connected would stop it working - never experimented - but it would be a pain to have to reset all your settings each time.

Have seen people take both live feeds off permanent so they can have the kit on without the ignition, but both lives were connected.
 
GreenLove said:
Ah, I might be getting my wires crossed here. I thought the ignition live provided the power needed for the stereo to function, but perhaps it just acts like a switch telling the stereo that it's ok to operate (the actual power being taken from the permenant live.) In other words, if I didn't have a permenant live connected but only the ignition live connected to the stereo, then the stereo wouldn't function at all. Is this correct?
Click to expand...

Unless someone corrects me.
the ignition live just tells the stereo to turn off when the car turns off, the power is fed from the Permenant live which as Station House says also allows it to hold its memory when the power is turned off.
 
BearDy89 said:
images
Click to expand...

Have you got a link to the 20A relay product please?

Incidentally, I do have two fuse slots spare in the existing fuse box. So if I wasn't too worried about adding additional equipment later on, could I just run new wires (have loads of 30A rated wired knocking around) from a spare fuse box slot then splice in to the lighter ignition live? I presume that the main fuse box has a direct 12V feed from the battery and should cope with a 10A stereo being wired up to a spare fuse slot?
 
Last edited:
Im not sure that the fuse box will have a single 12v Feed into it.

But you could use the spare slot and run your own feed from battery up to it.
This will only give a permenant feed though not an ignition switched feed
 
FYI:

Relay
PIN WIRING:
87 = Feed from Battery
86 = Ignition Feed from LR wiring
85 = Ground
30 = Feed OUT (I.e fuse box in this case)
 
Just remember any supplies you are taking direct from the battery must be fused as close to the battery as possible. Where are you, perhaps someone can come and point you in the right direction. Trust me I am an electrician with 35 years experience. :D :rolleyes:
 
The stereo will work ok without the permenant live , but as stated already you will lose all presets when the ignition is turned off. You can wire both the ignition and permenant live together to a perm live, you will just have to remember to switch the stereo off when you leave your Landie. Best suggestion i think is the relay and fusebox idea which gives you options in the future.:)
 
GreenLove said:
Do you think these will do the job, sir? SELF STRIPPING INLINE STANDARD BLADE FUSE HOLDER QTY 2 | eBay

Also, I was planning on using 30A rated cable. I'll probably stick with 20A fuses to be safe. Do you think this will be ok?
Click to expand...

personally I would steer clear of scotch block connectors and make either a screw connection or a crimp connection.

The blade connection on scotch blocks corrodes/reacts then starts arcing causing carbonisation thereby causing a high resistance causing more carbonisation etc etc. If you gonna do the job Do it right as posts above re relays and fuse boxes imho
 
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