Stereo Wiring Help

[scoey1001]

Hi everyone, is anyone good with stereos/wiring? Have a mk5 gti that came with a good stereo (Pioneer SPH-DA230DAB) and the guy who sold me it said it just needs an ISO harness

So I bought the harness, plugged it in but no power whatsoever to the stereo. I've tested and getting 12V from the car side so guessing it must be the head unit itself unless there is something else that could stop it powering on. Here are some pics of behind the dash, sorry they are not the best.

[scoey1001]

[defblade]

The usual problem with stereo power is the permanent live and ignition switched live being swapped. That would be the red and yellow wires. So I'm very suspicious of the last photo where a red wire and a yellow wire both appear out of the insulating tape, seem to have fuse holder bits on, but don't seem to be connected to anything on the other end of those bits. Hard to say any more from those photos, but I'd be investigating those.

[scoey1001]

defblade said:

The usual problem with stereo power is the permanent live and ignition switched live being swapped. That would be the red and yellow wires. So I'm very suspicious of the last photo where a red wire and a yellow wire both appear out of the insulating tape, seem to have fuse holder bits on, but don't seem to be connected to anything on the other end of those bits. Hard to say any more from those photos, but I'd be investigating those.

Hi thanks for the reply, after further reading i understand as you say there are two lives red and yellow. The car is at my father in laws and he has confirmed i am getting 12V at both red and yellow (i think the bits with the fuse holders may just be old redundant wiring). Only thing is i took the wiring harness to my house so he has only tested from the 'car side'. Next thing will be to check i am getting 12V at the end of the harness on both red and yellow. If not it must be the unit at fault?

[Bobberoo99]

scoey1001 said:

defblade said:

The usual problem with stereo power is the permanent live and ignition switched live being swapped. That would be the red and yellow wires. So I'm very suspicious of the last photo where a red wire and a yellow wire both appear out of the insulating tape, seem to have fuse holder bits on, but don't seem to be connected to anything on the other end of those bits. Hard to say any more from those photos, but I'd be investigating those.

Hi thanks for the reply, after further reading i understand as you say there are two lives red and yellow. The car is at my father in laws and he has confirmed i am getting 12V at both red and yellow (i think the bits with the fuse holders may just be old redundant wiring). Only thing is i took the wiring harness to my house so he has only tested from the 'car side'. Next thing will be to check i am getting 12V at the end of the harness on both red and yellow. If not it must be the unit at fault?

Before you bin the unit check the fuse on the rear of it, these can blow if there's a fault, there will be a wiring diagram online so plug the harness in and check that you're getting power at the unit end of the harness, if you are then check the units fuse.

[scoey1001]

Bobberoo99 said:

scoey1001 said:

defblade said:

The usual problem with stereo power is the permanent live and ignition switched live being swapped. That would be the red and yellow wires. So I'm very suspicious of the last photo where a red wire and a yellow wire both appear out of the insulating tape, seem to have fuse holder bits on, but don't seem to be connected to anything on the other end of those bits. Hard to say any more from those photos, but I'd be investigating those.

Hi thanks for the reply, after further reading i understand as you say there are two lives red and yellow. The car is at my father in laws and he has confirmed i am getting 12V at both red and yellow (i think the bits with the fuse holders may just be old redundant wiring). Only thing is i took the wiring harness to my house so he has only tested from the 'car side'. Next thing will be to check i am getting 12V at the end of the harness on both red and yellow. If not it must be the unit at fault?

Before you bin the unit check the fuse on the rear of it, these can blow if there's a fault, there will be a wiring diagram online so plug the harness in and check that you're getting power at the unit end of the harness, if you are then check the units fuse.

Hi, have only inspected the fuse visually but looks fine. Hoping I don't have to bin the unit as it's still selling for £400 online so worth saving if possible, although i don't know how easy it would be for someone to diagnose/fix. Will be checking I have power at the end of the harness tomorrow, I already know the red wire has power just need to check the yellow.

[RazerSauber]

Definitely check at the end of the harness. You'll need 12V at the yellow when the ignition is on and 12V at the red permanently. That's the way they usually go anyway.

I too am worried about why there's fuses attached to live wires that go nowhere. If you don't get 12V at the end of the harness, pop those fuse holders open and see if you get 12V there. You can then probably just attach the wires again with a blob of solder.

My checks would be:

Ground check from end of harness to car
12V check (Red and Yellow) at harness end
12V check at the car side of your new stereo ISO connector (The bit of the original car, not your new bit)
12V check at red and yellow fuses that are hanging out
12V on fuse box fuses, both terminals of each fuse

Obviously, don't carry on doing checks if you have 12V at the end of the harness. If that's all OK then you know you've got power to the head unit and a ground from the head unit. Check the fuse on the back of the stereo then to see if there's life in that. If you've got 12V going in, a good fuse and a good earth then you can probably consider the stereo as junk and get on eBay.

[scoey1001]

RazerSauber said:

Definitely check at the end of the harness. You'll need 12V at the yellow when the ignition is on and 12V at the red permanently. That's the way they usually go anyway.

I too am worried about why there's fuses attached to live wires that go nowhere. If you don't get 12V at the end of the harness, pop those fuse holders open and see if you get 12V there. You can then probably just attach the wires again with a blob of solder.

My checks would be:

Ground check from end of harness to car
12V check (Red and Yellow) at harness end
12V check at the car side of your new stereo ISO connector (The bit of the original car, not your new bit)
12V check at red and yellow fuses that are hanging out
12V on fuse box fuses, both terminals of each fuse

Obviously, don't carry on doing checks if you have 12V at the end of the harness. If that's all OK then you know you've got power to the head unit and a ground from the head unit. Check the fuse on the back of the stereo then to see if there's life in that. If you've got 12V going in, a good fuse and a good earth then you can probably consider the stereo as junk and get on eBay.

Thanks, i know i have 12V at the end of the harness on the red and also ground. It's just the yellow i need to check as i didn't know that was a second live. Can the stereo fuse still be knackered even with no visual signs? if so i will get another just in case. Also, can these units ever be fixed? I.e what breaks internally, as it would cost me £400 to replace i'd rather someone have a look inside if its possible it could be repaired.

[Brian_996TT]

i had a quick look online for a wiring diagram but found the manual and prior to powering up for the first time you have to put the ignition on so the stereo has power then use a ballpoint pen to press the reset button on the faceplate.

[scoey1001]

Brian_996TT said:

i had a quick look online for a wiring diagram but found the manual and prior to powering up for the first time you have to put the ignition on so the stereo has power then use a ballpoint pen to press the reset button on the faceplate.

Interesting, where does it say this in the manual please? Got to be worth a try.

[Brian_996TT]

scoey1001 said:

Interesting, where does it say this in the manual please? Got to be worth a try.

on page 6
Basic operation
- resetting the microprocessor

[Bobberoo99]

Yep, had to reset my Fh-S820dab when I installed it!!

[scoey1001]

Bobberoo99 said:

Yep, had to reset my Fh-S820dab when I installed it!!

Was that before it showed any signs of life at all? Had it previously been used in another car or brand new?

[scoey1001]

Brian_996TT said:

scoey1001 said:

Interesting, where does it say this in the manual please? Got to be worth a try.

on page 6
Basic operation
- resetting the microprocessor

Thanks, will give it a go tomorrow.

[Bobberoo99]

scoey1001 said:

Bobberoo99 said:

Yep, had to reset my Fh-S820dab when I installed it!!

Was that before it showed any signs of life at all? Had it previously been used in another car or brand new?

RTFM as a friend and ICE guru once told me, Read The fking Manual, it says that once wired in the unit will need to be reset at the start to allow the processor to reboot!!

[scoey1001]

Still no go with this :-(. Will try and get the unit bench tested this week.

[Brian_996TT]

scoey1001 said:

Still no go with this :-(. Will try and get the unit bench tested this week.

i’ll look at the wiring for the stereo and make sure there’s no extra power wires than usual

[Brian_996TT]

Sorry i couldn’t find one so hopefully the bench test shows it works

[scoey1001]

Brian_996TT said:

Sorry i couldn’t find one so hopefully the bench test shows it works

Thanks anyway. Yes fingers crossed.

[scoey1001]

Turns out the unit has had it. I asked about possible repair but the guy seemed to reckon it wasn't worth trying. Will stick it on eBay as 'faulty', bit gutting as it will cost circa £400 for a replacement.