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Discussion Starter · #1 ·
New single din stereo installed. It's an ISO plug jobbie and from what I can see all the wiring and plugs are original so nothing swapped around by previous owners.

So the stereo won't switch on unless the engine has been started and then turned off (with key left in the ignition. Switches off when you remove the key).

The stereo works fine on the scenario above (radio, blue tooth etc.). The problem is when I start the engine the stereo just keeps restarting so can't have any music while driving.

I read some posts on here which make me think that is something to do with the ignition switch. But before rushing out and creating more problems wanted to check if it could be old ISO plug wirings Vs new Stereo wirings.

Can anyone help?
Attached a couple of pics of the iso plug
 

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Full of Cr*p....
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100's of posts about swapping the red/yellow wires over.
VW and Grundig/Bluepunkt used different wiring to most. (Typical Germans!)
Red/yellow "should" have connectors on them to swap around.
If not...you have to rewire them yourself....or get an adaptor from the likes of Halfrauds.
 

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Discussion Starter · #3 ·
100's of posts about swapping the red/yellow wires over.
VW and Grundig/Bluepunkt used different wiring to most. (Typical Germans!)
Red/yellow "should" have connectors on them to swap around.
If not...you have to rewire them yourself....or get an adaptor from the likes of Halfrauds.
I tried that yesterday. I don't seem to have a clear red & yellow wires.

I tested the wires with a multimeter with engine off and then on. Nothing coming out the yellow but seemed like the grey and blue wire had 12v when engine on and 0v when engine off. Swapped it round with the red and blue and stereo didn't work at all. Swapped it back of course
 

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Discussion Starter · #4 ·
Ok so based on the reply and reading a lot more posts on stereos and wiring. Sounds like I need to swap the red and yellow around.

I don't have a clear red or yellow wire so I have drawn out the following for what my iso looks like. Does anyone know what each wire is below?
Handwriting Font Triangle Rectangle Writing


Similarly I have drawn out the diagram for the inputs on the new Stereo.
Handwriting Tartan Font Rectangle Wall
 

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OMG!
You are about as "hi-tec" as me when it comes to diagrams (and I'm a computer/electronics engineer with 50 years background in it!)......oh...I'm also COLOUR-BLIND....imagine explaining that to your boss after working as a service engineer for 5 years!?!?!?

Pin 1 should be a speed signal.....used to adjust the volume in "advanced" cars.
Pin 2 is a "phone mute" connection.....turns the music off if the 'phone rings....old school, before BT.
Pin 3.....?!?!?
Pin 4 should be a constant +12v supply.
Pin 5 is an OUTPUT for either an electric antenna or to switch on an external amplifier.
Pin 6 is an "optional" one that will dim the display when headlights are turned on...that depend upon the head unit..but VERY common on new ones....and even originals!
Pin 7 should be the switched 12v from the ignition....Ign on..."Radio on", Ign off.."Radio turns off after 1 hr" (Std)
Pin 8 "Ground/earth".....Germans DO have a sense of humour...this wire is normally BROWN....the colour of "earth" (mud).

All that is the STANDARD ISO connections.

Maybe, and it's quite common, you have "blown" the very light current contacts in the ignition switch.
10 quid or so, and 30 mins to replace it.

Pin 4 should have the 12v all the time.
Pin 7 should have 12v with key in pos 1, and see below.
Key in and turned to 1st position, radio should come on.
Turn to "crank", radio should go OFF!!!! (Radio goes OFF so not to get damaged by spikies in the electrical supply from cranking the engine!)
Engine started, radio should come back on.
Engine stopped, key still in ignition, radio still works (for an hour?).
Key out....radio dead.

Later....ANYTHING on the "radio" should come back to how it was once you put the key back to position 1.
(Saved stations, where you were in any CD you were playing, and point on a memory stick..etc)
I typed "Radio" as it's just old school for that 4xcpu/bluetooth/ipod/ digital whatever you've put in the dash.

BTW....hope you took my comments about seatbelts etc in your other thread as it was meant!
 

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ignition switch is a very common failure and inexpensive - if a faff - to replace. Its one of very few parts that is worth replacing in the hope that out might fix something!

Especially when it does look like its faulty.
 

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Discussion Starter · #7 ·
OMG!
You are about as "hi-tec" as me when it comes to diagrams (and I'm a computer/electronics engineer with 50 years background in it!)......oh...I'm also COLOUR-BLIND....imagine explaining that to your boss after working as a service engineer for 5 years!?!?!?

Pin 1 should be a speed signal.....used to adjust the volume in "advanced" cars.
Pin 2 is a "phone mute" connection.....turns the music off if the 'phone rings....old school, before BT.
Pin 3.....?!?!?
Pin 4 should be a constant +12v supply.
Pin 5 is an OUTPUT for either an electric antenna or to switch on an external amplifier.
Pin 6 is an "optional" one that will dim the display when headlights are turned on...that depend upon the head unit..but VERY common on new ones....and even originals!
Pin 7 should be the switched 12v from the ignition....Ign on..."Radio on", Ign off.."Radio turns off after 1 hr" (Std)
Pin 8 "Ground/earth".....Germans DO have a sense of humour...this wire is normally BROWN....the colour of "earth" (mud).

All that is the STANDARD ISO connections.

Maybe, and it's quite common, you have "blown" the very light current contacts in the ignition switch.
10 quid or so, and 30 mins to replace it.

Pin 4 should have the 12v all the time.
Pin 7 should have 12v with key in pos 1, and see below.
Key in and turned to 1st position, radio should come on.
Turn to "crank", radio should go OFF!!!! (Radio goes OFF so not to get damaged by spikies in the electrical supply from cranking the engine!)
Engine started, radio should come back on.
Engine stopped, key still in ignition, radio still works (for an hour?).
Key out....radio dead.

Later....ANYTHING on the "radio" should come back to how it was once you put the key back to position 1.
(Saved stations, where you were in any CD you were playing, and point on a memory stick..etc)
I typed "Radio" as it's just old school for that 4xcpu/bluetooth/ipod/ digital whatever you've put in the dash.

BTW....hope you took my comments about seatbelts etc in your other thread as it was meant!
Amazing, thanks for the detailed instructions.

I got in the Van with my multimeter today and following your advice worked out which wires are ign and perm. They behaved as you described with the key in/out and shaking it all about.

Unfortunately after swapping the wires round to match the stereo inputs on the manual it still switches on and off when the engine is running but works fine when engine is switched on then off.

Measuring voltages in the different key States though, voltage drops from 12.3 on the perm wire down to 11.6 volts when the engine is running then back up to 12.3 when engine is off.

Similar on the ign wire 0 volts when off, 11.7 with engine running, then 12.3 when engine switched off but key left in.

Is this voltage drop enough to cause the stereo to keep switching on and off?

Any help would be much appreciated, I can only coast with the engine off for so long
 

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Just a hunch, but check the "earth spider" at the side of the fuse box.
There's 5-15 wires attached to it....remove them one at a time, spray with Servisol switch cleaner (NOT WD40!) and replace.
LOADS of thing run through that, and if one of them is not making good connection, can cause a voltage drop in the fusebox.
Also....there is only ONE main supply into that box....and it has to run everything connected to it.

See the threads/post on the fusebox....there are a lot of problems show up on 20+ year old vans.
 

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Discussion Starter · #9 ·
Just a hunch, but check the "earth spider" at the side of the fuse box.
There's 5-15 wires attached to it....remove them one at a time, spray with Servisol switch cleaner (NOT WD40!) and replace.
LOADS of thing run through that, and if one of them is not making good connection, can cause a voltage drop in the fusebox.
Also....there is only ONE main supply into that box....and it has to run everything connected to it.

See the threads/post on the fusebox....there are a lot of problems show up on 20+ year old vans.
Stupid question but after lots of googling and searching on here I can't self help.

Where is this promiscuous Spider you speak of?
I looked all around the fuse box (Drivers side right knee) please help
 

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You need to remove the fuse box....2 white clips..one each side.
A "bit" like clothes-pegs...
You'll also have to remove the "strengthening" bar attached to the steering column....3 x 13mm nuts if I remember correctly. (I assume RHD has this the same as LHD....it's a metal triangle plate.)
This allows the 'box to be dropped, and gives access to the "spider" and rear connections.

You're RHD....but it's just a mirror image of my LHD setup.
They'll all be brown wires....the colour of mud...so "Earth". :whistle:

Check the voltage at the battery with engine running....it should be 14.2 - 14.4 volts at 2000rpm.
On tickover, with nothing else on, you should still get 13.8 volts or more.
IF you have that at the battery, but only 12ish volts at the fuse box, there is a major voltage drop somewhere.
Problem with RHD vans....VW left the battery at the other side of the van....and the ECU, and all the sensor wiring!
Saved a few deutschmarks at the time, but has caused loads of problems later with the extra lengths of wire.

As for the earth connections under the bonnet....there are a few.
Again, they will be brown wires, either to the battery (I think there are 5 on mine) or to various "studs" on the panels.
Often, if someone has been messing with the wiring (adding things), there may also be a self-tapper or 5 with earths connected.
THIS can be a problem, as any "aftermarket" wiring is often black wires. (Which the Germans use as a +12v colour!)
 

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Discussion Starter · #11 ·
You need to remove the fuse box....2 white clips..one each side.
You'll also have to remove the "strengthening" bar attached to the steering column....3 x 13mm nuts if I remember correctly.
This allows the 'box to be dropped, and gives access to the "spider" and rear connections.

You're RHD....but it's just a mirror image of my LHD setup.
They'll all be brown wires....the colour of mud...so "Earth". :whistle:
That makes sense.

At the time I stupidly thought "They wouldn't put it behind this piece of bolted metal!" and they have. I shall have another go in my next window of opportunity.

Cheers
 

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At least YOU don't have to go fix a Smart ForTwo that keeps "just stopping", but starts again.....
Have a "pirate copy" of the Mercedes software, that shows NO errors...probably 'cos the power just disappears for a second or 2.
And I have over a foot of snow in the drive.
Only way to get to the engine is to remove the whole rear of the car.... :eek:

I "suspect" (and you may now laugh), that it is an "earth" problem between engine and chassis!
The "flexy" cable between block and body is known to be a problem....and it is 16 years old, and currently has 197,850 on the clock! (Or 7pm....depending upon which clock you look at..:whistle: )
 

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Discussion Starter · #13 ·
So, Had a quick disasemble of the fuse box but couldn't see any spiders. I did see a brown wheel with lots of plug connectors, is that what you mean?

I also followed your advice and also watched a you tube video someone recomended on the forums to test the alternator. What my multimeter measures is 12v Engine off 11.3 engine on.

So looks like I have either earth problems or alternator problems.
Does anyone have any pics or vids on where
Alternator earthing points are (Bracket, Engine block etc.)?
Also where the battery to chassis Ground is?

I would like to keep getting through the various tests and cleaning contacts before I concede that a new alternator is neeed.

Apologies for the basic Q's this is all new to me so I only have Youtube videos and what i can find in the forums to slowly crawl through the broken glass and get this bloody stereo working!

Cheers
 

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Yeah, that brown wheel is your spiders web of "earth" contacts.

Not sure where the main earth is, but possible the bell housing.....It'll be the thickest cable you can find (after the starter motor one).
Just follow the thickest brown wire from the battery -ve to where it goes.

99% you won't need a new alternator...just the brush pack/regulator that costs around 30 quid and can be done in situe.
 

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Battery to chassis ground is directly below the battery itself - follow the big negative cable down to it. It then goes on to the end of the gearbox. It can be a bit tight and seems to be at risk of breaking.

Speaking of spiders, mine looks a bit sick -

Automotive tire Motor vehicle Alloy wheel Automotive lighting Steering wheel


I don't know whether to be thankful or envious that I've only got two wires in mine!
 

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Discussion Starter · #17 ·
Battery to chassis ground is directly below the battery itself - follow the big negative cable down to it. It then goes on to the end of the gearbox. It can be a bit tight and seems to be at risk of breaking.

Speaking of spiders, mine looks a bit sick -

View attachment 199955

I don't know whether to be thankful or envious that I've only got two wires in mine!
I only have 2 too
 

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Discussion Starter · #19 ·
So Van is back from passing its MOT today, after needing some new crocodile boots for the steering rods.

I sneakily asked them if they could do a quick test of the alternator while they had it on the ramps.
The alternator is kicking out 14 volts but only once the engine is revving, which they said is a sign it is on its way out.
They also checked the cables from the alternator to the battery and said they tested fine.

So guess I will be looking at new alternators now and whether to get a higher Amp one ready for the leasure battery. Anyone have any suggestions on how to bring this cost down? I hav been quoted £460 (Part (£307) and fitting).

In the mean time I will try the radio out now I have switched the wires over to see if it works ok while driving.
 
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