[bstaley]

Assuming you have non-JBL I believe these are the colors:

FRONT

Left + = Pink
Left - = Violet
Right + = Lt. Green
Right - = Blue

REAR

Left + = Black
Left - = Yellow
Right + = Red
Right - = White

 

[bstaley]

Okay for JBL at the head unit:

L+ = Black
L- = Green
R+ = Red
R- = White

But I'm not sure those signals are usable, because I have heard that they used a digital signal between the HU and the Amp on the JBL's. So what you probably need to do is tap the signals coming out of the Amp, which should be located behind the plastic panel that covers the back wall of your cab. The colors to look for there should be:

Front Left:

Woofer + = Green
Woofer - = Blue/White
Tweeter + = Pink
Tweeter - = Violet

Front Right:

Woofer + = Black/Yellow
Woofer - = White/Blue
Tweeter + = Lt. Green
Tweeter - = Blue

Back:

Left + = Black
Left - = Yellow
Right + = Red
Right - = White