Wire behind iso block has been snipped


Standard Member
As you may have read ive been having problems getting my headunit to come on.

Look at this pic....

The brown wire continues with the loom behind the dash

But the RED/Yellow wire which comes from the connector, then gets taped up with the orange, but i had a good look last night and it gets taped up with ANOTHER red cable!!!! which continues with the loom behind the dash.

So i thought to myself "better check behind the iso block then" and there is a red wire from the bottom block of the iso block that has been snipped about 5cm away from the block!!!


I will have to reconnect the red wire to the back of the block with a chocoblock? will that do?

But due to the fact that this iso block has been tampered with before from a previous owner, does anyone have any diagrams to show what colours i should have going to the back of the iso block (as there are 10-15 different cables)

And also i have a multimeter so does anyone have any information on what results i should get across each terminal.

Thanks for the help guys but one last question! :)

Also would it have damaged the headunit by not having a red terminated into the iso block, when the headunit was plugged into the iso block i heared the motor turning/laser moving in the headunit but the screen would not come on, even after i pressed the source (on) button.

Thanks again


Novice Member
This is not necessarily a major issue as it may be only the positive and switched positive which have been swapped over.Check them out with a meter or 12V test lamp. The switched positive will cease to be live with the ignition switch off.


Novice Member
As said by lynx they have probably been swopped due to Vauxhall using these leads the wrong way round, my Vectra had the problem that it would never hold its memory, on my Kenwood radio there were 2 leads in the radio-iso cable that had connectors in the middle all I did was swop them round and hey presto radio remembers things, what appears to have been done in your case is someone has swopped them over at on the loom rather than on the radio itself.
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