ab07ash

New stereo no power

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Hi all,. Changing the cd 6000 in my MK4 Mondeo for a Kenwood bluetooth unit.  I have the iso connector but the unit is not powering up.  I've put a tester between yellow and red and there should be 12v but nothing showing.  Fuse?? If so would any of you know which one.  The old stereo has power and works fine.  Cheers 

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21 minutes ago, ab07ash said:

Hi all,. Changing the cd 6000 in my MK4 Mondeo for a Kenwood bluetooth unit.  I have the iso connector but the unit is not powering up.  I've put a tester between yellow and red and there should be 12v but nothing showing.  Fuse?? If so would any of you know which one.  The old stereo has power and works fine.  Cheers 

Do you mean you've put a multimeter lead on yellow and one on red at the same time?  If so, that won't work as that the permanent live and the ACC (switched live).  You need to use one of the live feeds and whichever is the earth to get a reading.

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Or an earth on the chassis.

if you plug the old stereo back in does it power up, or do you mean it did power up before it was removed?

 

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1 hour ago, Jonro2009 said:

Or an earth on the chassis.

if you plug the old stereo back in does it power up, or do you mean it did power up before it was removed?

 

I previously had a related(ish) issue where the earth within the loom was bad so it looked like there was no power to the loom when I tested it with a multimeter (when I'd previously pulled the heater matrix out to fix the infamous leaking connectors and put everything back together, I'd forgot to reconnect the earth strap for the head unit loom :wallbash:

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2 hours ago, Jonro2009 said:

Or an earth on the chassis.

if you plug the old stereo back in does it power up, or do you mean it did power up before it was removed?

 

When I put the old one back in it works.  But the new one nothing.

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4 hours ago, 1979Damian said:

Do you mean you've put a multimeter lead on yellow and one on red at the same time?  If so, that won't work as that the permanent live and the ACC (switched live).  You need to use one of the live feeds and whichever is the earth to get a reading.

👍. I'll try that thanks 

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So it has to be the stereo and not the car/wiring. 

Is there a fuse in the stereo itself? 

Does the cars harness connect directly into the back of the new unit or does that have external wires and a plug?

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It does have a fuse I'll check that.  I've got an adapter harness between the car and the new stereo harness if that makes sense

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So this is the set up I have I've tested between the yellow and black shows voltage.  But nothing on the head unit itself 🤔

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16 hours ago, Jonro2009 said:

So it has to be the stereo and not the car/wiring. 

Is there a fuse in the stereo itself? 

Does the cars harness connect directly into the back of the new unit or does that have external wires and a plug?

If you could have a look at the photos below.  There's power in the harness and the fuse is ok in the stereo.

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Try switching the red to yellow and yellow to red on the stereo wiring, where you have the bullet connectors. 

The red is the Bat+ and the yellow is ACC

if switching the wires doesn’t work then if you disconnect the red and yellow wires at the bullets and test the voltage at the end of each wire (the end from the plug not the stereo). They should both carry a current with the ignition on and only one will have a current with the ignition off.

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I tried switching them and still no joy.  I have voltage on the yellow but not on the red.

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2 hours ago, Jonro2009 said:

Try switching the red to yellow and yellow to red on the stereo wiring, where you have the bullet connectors. 

The red is the Bat+ and the yellow is ACC

if switching the wires doesn’t work then if you disconnect the red and yellow wires at the bullets and test the voltage at the end of each wire (the end from the plug not the stereo). They should both carry a current with the ignition on and only one will have a current with the ignition off.

I tried switching them and still no joy.  I have voltage on the yellow but not on the red.

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I take it you’ve tried the stereo with the ignition on? 

With the ignition on leave the red wire disconnected and hook the yellow wire with power up to the red wire from the stereo. You should absolutely get something then, if not there is something wrong with the stereo somewhere, it could be a ground or it could be the stereo is broken. 

I know you said the fuse is good but have you taken it out and checked for continuity?

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1 minute ago, Jonro2009 said:

I take it you’ve tried the stereo with the ignition on? 

With the ignition on leave the red wire disconnected and hook the yellow wire with power up to the red wire from the stereo. You should absolutely get something then, if not there is something wrong with the stereo somewhere, it could be a ground or it could be the stereo is broken. 

I know you said the fuse is good but have you taken it out and checked for continuity?

I will check that yes checked the fuse for continuity and changed it for a new one too.  Thanks for your help it's had me scratching my head haha 

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It’s got me thinking too lol. 

On the plug coming away from the car I would recommend checking the pins to see which ones are carrying the power, it may be that the pins don’t match up properly and the power isn’t actually going to the right wires on the stereo. I can’t see it being that but it’s another diagnostic to cross off the list.

if the yellow wire isn’t getting power then connecting it to either the red or yellow wire with the engine running should produce a positive result. 

Is the stereo new? Check the contacts on the removable face are not corroded etc. 

The other thing I wondered was if the case itself has some sort of grounding on it that mean she it will only work if the stereo is actually seated properly in the cage inside the dash

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2 hours ago, Jonro2009 said:

It’s got me thinking too lol. 

On the plug coming away from the car I would recommend checking the pins to see which ones are carrying the power, it may be that the pins don’t match up properly and the power isn’t actually going to the right wires on the stereo. I can’t see it being that but it’s another diagnostic to cross off the list.

if the yellow wire isn’t getting power then connecting it to either the red or yellow wire with the engine running should produce a positive result. 

Is the stereo new? Check the contacts on the removable face are not corroded etc. 

The other thing I wondered was if the case itself has some sort of grounding on it that mean she it will only work if the stereo is actually seated properly in the cage inside the dash

I've been back to Halfords and they've plugged it in in the store and it works 🙈.  They did say that it must be a fuse as it should just plug in and play.  I've visually checked all of the fuses and none seem to have blown.  I will put a meter on them all to double check but I'm stumped otherwise. I'll have to make do with the old one 😭

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If you are getting power to the yellow wire then I don't see why it won't work under some condition. 

When does the yellow wire show a voltage, when the ignition is on or off? 

Check that pin A4 goes to yellow wire on the car harness and pin A7 goes to the red wire on the car harness, or vice versa at this point it doesn't matter.

 

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Also, check passenger compartment fuses 13, 28 & 39 as these relate to the stereo. 

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Just pulled up the manual for your stereo and it expects Yellow to be a permanent live and the Red to only be live when the ignition is switched on.

You'll need to use your meter and make sure that you have voltage on yellow and black at all times and a voltage on red and black when the ignition is switched on. If you are getting voltage but its the wrong way (ie red and black is permanent yellow is switched) then you swap the connections over at the bullets and try again. If you don't get any voltage at all on the yellow+black or red+black then you need to check your fuses and wiring.

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15 hours ago, Mark M said:

Just pulled up the manual for your stereo and it expects Yellow to be a permanent live and the Red to only be live when the ignition is switched on.

You'll need to use your meter and make sure that you have voltage on yellow and black at all times and a voltage on red and black when the ignition is switched on. If you are getting voltage but its the wrong way (ie red and black is permanent yellow is switched) then you swap the connections over at the bullets and try again. If you don't get any voltage at all on the yellow+black or red+black then you need to check your fuses and wiring.

I had suggested this in one of my first posts and the OP said he has swapped the wires about and it still doesn't work, the fuse in the stereo itself has been changed for one that has been checked for continuity so unless the fuse in the stereo keeps blowing or the connections on the face plate aren't working it's an odd one. 

If the old stereo gets plugged back in then it works which must mean the car side of things is fine and it has to be new stereo.

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4 hours ago, Jonro2009 said:

I had suggested this in one of my first posts and the OP said he has swapped the wires about and it still doesn't work, the fuse in the stereo itself has been changed for one that has been checked for continuity so unless the fuse in the stereo keeps blowing or the connections on the face plate aren't working it's an odd one. 

If the old stereo gets plugged back in then it works which must mean the car side of things is fine and it has to be new stereo.

Turns out there isn't/wasn't a switched live in the loom from the car (the stereo is permanently live as you can turn it on with no ignition) This is why the old one would work but the new one wouldn't.  So i've had to use a piggyback fuse from a switched live on the central fuse board and run a cable to the red bullet.  It now works thank christ co it was doing my head right in.  Thank you for all your advice.  got there in the end.

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