Cruise control not working 1.9tdi 130 tiptronic

[jwalman]

Hi, I have got a Passat 1.9 tdi 130pd se tiptronic on an 02 plate here with a cruise control problem. When you flick the switch on the stalk the green light on the dash comes on, but when you press the buttons on the stalk it will not engage the cruise control at any speed. I have vag commed it and there are no codes. Any ideas? Regards

[Crasher]

You need to check the inputs of the switch in measuring blocks but I suspect the brake light switch.

[jwalman]

Thanks, I will replace the brake light switch today and see if it fixes, theyre not expensive so Ill give it a go. One other problem with the car, Im getting a loud squeak coming from the belt area, from cold startup only, last for about 3-5 minutes. It goes away immediately if I 1)drive away immediately or 2) spray a small amount of WD40 on the alternator belt. Any ideas on this one? Thanks in advance.

[martin1810]

Don't ignore the squeak on these engines. It is usually a sign of the belt tensioner failing or the alternator one way pulley failing. When either fails, they can snap the belt and do more damage than you would imagine.

[Crasher]

Alternator one way clutch.

[jwalman]

Thanks for all the advice so far. Re cruise control, interesting one this : It wasnt working at all, then today the car went into limp mode for the 1st time ever. Whilst it was limping along at its max speed of 67mph, i decided to try the cruise control and it worked!! Upon further investigation, a vac hose had popped off, so I fixed it back on, drove it again and thankfully I got my 130bhp back, and tried the cruise again, it didnt work to start with, then it worked after a couple of presses, but then cancelled itself automatically whilst doing 75mph - twice. My technically knowledge is not the best, I was wondering, Is the cruise control linked up with the turbo vacuum pipes in some way? Why is my cruise now working, but only intermittently? I havent changed the brake light switch at all yet.

With regards to the alternator belt squeak, a bolt at the bottom which holds the tensioner on was very loose, and has now been tightened, hopefully this may solve the problem, I havent started the car in the cold yet to see if the squeak has gone.

[jwalman]

Also, its now brought up 17571 which is "Fuel Temp Sensor (G81): Open or Short to Plus" - would this affect the cruise control? Where is its location and is it cheap to replace? I understand it may increase the fuel consumption, which looks likely as Im only getting about 35mpg average. Anything else this sensor would affect? Thanks guys.