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Old March 4th, 2018, 10:17   #1
Jeffcee
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Join Date: Feb 2011
Location: Vancouver Island Canada
Fuel Economy: 5.7l/100km
Default Cruise Control Not Working

This is a report of my findings regarding a non-op Cruise Control on my car, as I could not find the correct answer on this forum.

2006 Jetta Wagon TDI, A4 body, BEW engine, 5 speed manual. This is essentially a 2005 model.

SYMPTOMS:
Cruise Control was non-op.
Cruise dash light came on when switched on (switch on the left hand stalk).
Cruise would not engage.
Brake lights all good and working normally.
No ECU faults (used an OBD2 with "Torque" application, simple scanner, no VAGCOM)
Cleared all faults anyway, no help.

ROOT CAUSE:
Lower clutch switch was physically broken. The metal contact inside was fatigued and broke loose.

VW has a new revision for this switch, looks much like the brake light switch.


A longer explanation:

Reading through many posts in this and other forums I was not able to find this fix. I did see several users rule out the clutch switch because the engine would start when the clutch pedal was depressed, therefore the clutch switch was declared OK. I found this to be incorrect.

However I initially bought into this logic and focused on the brake switch (which does have a cruise-disengage function). I was able to determine that switch was fine.

While looking around under dash I noticed there were TWO clutch switches. The lower actuated at the start of travel, and the upper actuated at end of travel. Clearly the upper switch was for the starter function. I pulled the lower switch and found the problem.

BE AWARE:
Both the clutch and brake switches have this clever self alignment feature where, when installing, you leave the pedals up and untouched, insert the switch and twist-lock it in place. The act of twisting engages little teeth inside the switch which engages the contact slider.

What this means is when you "un-twist" and pull out the switch the plunger disengages from the contacts. It will then appear non-op because you cannot make it change state. You can plunge the plunger all you want and it ohms out the same. So if you try to ohm it out (like I did) you may think the switch is stuck in one state.

Thinking it was stuck in one state I totally disassembled the brake switch, unaware of how it worked. I spent perhaps 30 minutes contemplating this silly thing before getting an understanding of what was happening. I was able to get it all back together. I then "test twisted" the switch on the bench and was able to verify it worked normally.

ALSO NOTE: The VW dealer told me the brake switches needed to be "reset" after removal. If you remove one, it's done regardless of it's working condition and needs to be replaced or reset. I'm not sure I buy into this, but perhaps I unintentionally "reset" mine when I had it apart.

I hope someone finds this useful. Regards to all.
Jeff C.
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