Ok folks, we keep getting the same question over and over again and it is starting to get frustrating. So I have decided to give a brief run through on what to do. this information can be applied to any vehicles with non ISO stereo's as well. This will tell you how I do it. My methods may differ slightly from other engineers in the equipment that I use, some engineers frown on using a test lamp and use a meter.
This section is for guidance only! I will not be held liable for damage caused to your stereo by following any of the instructions that follow! Any auto electrical work should always be left to a competent person who knows what they are doing!
Knowledge
If you do not understand what a 12 volt positive feed is, or a 12 volt switched live or an earth is, then you do not have the required knowledge to do this yourself! If in doubt, pay a professional to do it for you!
You will require
Wire strippers
small cable ties
radio removal keys
Radio code (where applicable)
1 x 12 volt automotive test lamp. i use a snap on 12 volt one which is about £30.00, you can get a semi decent one from most good car accessory shops for about £10.00
Alternatively, you can use a 12v bulb holder with two wires on it and a low wattage bulb (5 watts or less or there will be too much resistance for it to work!), put a crocodile clip on one end and bare back the wire and solder (tin) the end.
ISO PLUGs
By far the most common plug in French, German, Italian cars and aftermarket accessory radios.
The picture below shows ISO plugs with common mute positions and common earth and 12v live posistions for 99% of ISO radios (excl kenwood, they usually have a blanking plug and Sony have an ATT wire).
Image above is viewed from the radio side of the plug, in other words, if you unplug the ISO's from the radio, this is what you will see. The top plug with nothing written on is for the front and rear speakers.
Checking for a mute
Pop the radio out
check for a pinout label on the top, some tell you the tel mute posistion
if no label then switch radio on
connect one end of testlamp to earth/ground/radio chassis
probe the positions above, if the sound dims or cuts out check the display and see if it says phone/tel/mute/ATT if so you have found the mute
insert the mute wire in that position and secure with a cable tie.
Heres exactly what i have described in a Citroen C5 and I found the mute in about 35 seconds tops! N.B. do not use the fuse method on this vehicle to test for mute, arcing will blow the ECU!!!
This technique can be used on any car, if you don't understand any of the above or cannot find the mute, call in a professional.
