ballast

[burdar]

Is there a difference between the left and right sides of a 4 prong ballast resistor?  Does it need to be mounted in a specific possition so the wiring is connected to a certain side?  Right now I have mine mounted with the open slot in the lower possition and the hole in the upper possition.  Some pictures I've been looking at show the open slot in the upper possiton.    I'm ready to plug the wiring in and want to make sure I don't need to turn the ballast 180 degrees.  Thanks

[Bullitt-]

Just looked and my slot is on top, the one time I replaced it 4-yrs or so ago I would have oriented to be like OE
I don't think you can wire one wrong, but let me think about that. 

[Bullitt-]

Looking at it you can't plug it in wrong,  mine is brown & green on top blue & black bottom

[dodj]

Looking at it you can't plug it in wrong,  mine is brown & green on top blue & black bottom

The way the index tabs on the connectors work, you can't connect it wrong. Wire harness will fit better one way though.

[72rtchallenger]

being its just a resistor I dont think it matters which end goes up,,if it did they would have marked it as so,,as long as it is plugged in right you should have no problems

[Chryco Psycho]

Both sides of the ballast are different resistance , the hole at one end |& the slot at the other forces the plug to only go on one way IF the factory plugs are there & are not altered .
Typically most ECUs have only 4 pins , if so the one side of the ballast is never used so you can use a single ballast on the side that does NOT have the green / red wire , you need to connect to the blue /yellow trace wire

[burdar]

Thanks everyone.  I can see now that there's no way to hook it up wrong with the factory style connectors.  I'm going to flip it and see if the harness fits better that way.  My replacement ECU is a 5 pin.