Cooling fans

[Norman57]

06 Jetta 1.9 BRM engine , installed new set of fans, power wire has power, ground is good, 1 small wire has power when key is on, other wire is the one that starts the fans, where does this wire get its power from?

 

[TurboABA]

You asking about the yellow\purple?

 

[325_Guy]

What is the issue?

 

[Norman57]

If the yellow purple is the one that turns the fan on, then yes

 

[Norman57]

325_Guy, fans won't turn on, power to the fans has power, Ground is good, One small wire has power when key is on, other small wire, no power. A/C is charged and working, but fans won't turn on, brand new fans installed.

 

[Rx7145]

I would do the output test in VCDS if that doesn’t work it’s gotta be the wire or the computer.

 

[TurboABA]

If the yellow purple is the one that turns the fan on, then yes

You said you've tested the other 3 wires... so I would assume that you know what color the one small wire you tested was no?
Or are you saying the wire is completely missing?

 

[Norman57]

Wire is there, no power on it.

 

[TurboABA]

Goes to ECU

 

[Rx7145]

It may provide a ground to turn the fans on. In any case, the ECU controls the fans or is supposed to.

 

[325_Guy]

It may provide a ground to turn the fans on. In any case, the ECU controls the fans or is supposed to.

100%. Which is why OP needs to run the fan output test in VCDS as you recommended earlier and go from there.

 

[TurboABA]

I'd suspect a controller issue if these are already in.... the typical failsafe mode is for the fan(s) to run full bore if they don't see PWM signal.