standard headunit problem

[blink-182]

Having a problem fitting a headunit back into my 182. The Headunit is out of a 2001 clio and was working when i took it out, when i put it into the 182 there are only three plugs: black and white main ones, then a small yellow one. On the headunit there is also space for a blue plug, is this needed or just for an autochanger?
Anyhow, if i plug the three plugs in the headunit powers on but nothing is displayed on clock display screen so i cant enter a security code etc.

If anyone can actually understand what im on about, id appreciate some help!

Cheers,
Jordan

 

[ThomasBrentnall]

The blue plug is for the 6 cd changer, but isn't crucial for the operation. Make sure the yellow plug is in correctly though!

 

[Beef-Mc]

Have you used the headunit in your 182 before?