Any auto electrickyians whose brains I can please?

Basically I’ve an old Disco 1. Someone has swapped out the head unit. It had been replaced with an old cd/dab unit that was held together with duck tape. It wouldn’t stay switched on and tuned in so I tore it out.

I bought a cheap single DIN Chinese Apple CarPlay unit, it plugged straight in, powered up and played through the existing front and rear speakers. However it had a mind of its own own. It would switch between CarPlay and FM and the volume would go up and down of its own accord. I put this down to the knock off characteristics of the unbranded cheap and cheerful manufacturing.

Boosted by the fact I had power and sound I invested in a really good Pioneer CarPlay head unit. Somewhat disappointed to discover this is behaving in the exact same way as both the previous units! So clearly there’s something wrong with the wiring.

Any clues please where to start? Could it be an earthing fault?

Cheers in advance!

Mr Wom said:

Any auto electrickyians whose brains I can please?

Basically I’ve an old Disco 1. Someone has swapped out the head unit. It had been replaced with an old cd/dab unit that was held together with duck tape. It wouldn’t stay switched on and tuned in so I tore it out.

I bought a cheap single DIN Chinese Apple CarPlay unit, it plugged straight in, powered up and played through the existing front and rear speakers. However it had a mind of its own own. It would switch between CarPlay and FM and the volume would go up and down of its own accord. I put this down to the knock off characteristics of the unbranded cheap and cheerful manufacturing.

Boosted by the fact I had power and sound I invested in a really good Pioneer CarPlay head unit. Somewhat disappointed to discover this is behaving in the exact same way as both the previous units! So clearly there’s something wrong with the wiring.

Any clues please where to start? Could it be an earthing fault?

Cheers in advance!View attachment 307277

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Your going to need a electric multi metre.
Should be two iso plugs. One will the speakers. 8 wires, grey pair, purple pair, green pair and a white pair. Each pair will have a solid colour on one and a black tracer line on the other.
Other plug will be the power. I can't remember the colours of this one. Check for a permanent 12v and a ignition on switched 12v live. Also one will be 12v when lights are on. Check these are all stable.
There will be another small plug which is the amp for the subs in the rear door.
Just check there volume buttons next to your Speedo aren't connected or anything really weird.
A lot of new stereos have automatic steering wheel connectors. Just check all the wiring for now.
There is someone on here who does his own fantastic writing diagrams. He might be asking tho help.....

Any thing other than the original Phillips head unit isn’t compatible with the existing loom connectors.
The only thing you can do its tap into the existing head unit feeds - as currymunster listed above- that you require which are in the dash, ie, loudspeakers, power, illumination and antenna. Your Pioneer head unit, if it has a bass pre-out, can be linked to the tailgate sub amp should you have one fitted, and forget the Phillips 6 CD player under the seat, again if you have one fitted.

discool said:

Any thing other than the original Phillips head unit isn’t compatible with the existing loom connectors.
The only thing you can do its tap into the existing head unit feeds - as currymunster listed above- that you require which are in the dash, ie, loudspeakers, power, illumination and antenna. Your Pioneer head unit, if it has a bass pre-out, can be linked to the tailgate sub amp should you have one fitted, and forget the Phillips 6 CD player under the seat, again if you have one fitted.

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What about if the tel mute wire or something is somehow connected to a wire. Someone may have moved one of them In there iso plug i suppose.
I had that with the illumination wire once. Someone had removed the individual wire and put it back in the wrong place.. just a off rock thought..lol

currymunster said:

What about if the tel mute wire or something is somehow connected to a wire. Someone may have moved one of them In there iso plug i suppose.
I had that with the illumination wire once. Someone had removed the individual wire and put it back in the wrong place.. just a off rock thought..lol

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I have a clue on what wiring alterations have be made to the OPs disco, but in the wiring redundancy that a D1 has, there is not a wire for that specific facility in a D1.

The only way to have that function in a D1 is install a head unit with that facility or a standalone mobile car kit installed with a compatible head unit.
Ive had the second option for years in my disco to make and receive calls not that I use it that much.

Does this disco have the steering wheel buttons for the stereo? I'm wondering if the previous owner had put in an interface box for the steering buttons and those are now causing un-commanded signals to be sent to the head unit?