Cruise Control Repair - 80's & 90's Modules

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Cruise Control Repair - 80's & 90's Modules

Postby DieGTi on Jun Thu 24, 2010 5:16 pm

Thanks to a buddy of mine that works at http://www.Europrice.us for a dash diagram so I didn't break my interior to bits getting to my cruise control module. The cruise control had been functioning intermittently since I purchased the car and then it quit entirely about 3yrs ago. The modules are notorious for solder joints cracking and so today's project was to remove the module for servicing. Here's a quick how-to for any other b5 audi owners; this repair should also work for older modules such as 80's and 90's VW's. Took about an hour and a half start to finish taking my time and I have cruise control again for the first time in years. :)

Simple tools - 8mm socket, 1/4" drive ratchet, flat head screw driver, soldering iron
Step 1 - Remove passenger side dash plastic (the one you access when you open the door, there's a slot on the bottom for a flat head screw driver to get behind it to pry off. Be gentle, these crack easy if you don't apply pressure evenly)
Step 2 - Remove black 8mm bolts that now exposed and are parallel with the ground but perpendicular to the L/R center line of the vehicle. The glove box should now swing down as pictured below.
Step 3 - Remove the single mounting bolt for the cruise control unit. If you look into the area behind the glove box the aluminum box module is at the top of the open cavity with 1 x 8mm bolt holding it in place. The mounting bolt is vertically positioned between the module and the face of the dash; I was able to loosen it easily reaching over the top of the glovebox with a 1/4" ratchet and deep 8mm socket.
Step 4 - Unplug harness from module and remove from vehicle.
Step 5 - Open module case; a large flat head screw driver works here- you should be able to twist the screw driver rather than using it as a lever to lift the casing tabs.
Step 6 - Gently remove the circuit board from the case. The board may be jammed in the case and difficult to remove at first. Do not yank on the board in an attempt to dislodge it, simply squeeze the fat sides of the aluminum casing lightly and the board should slide right out.
Step 7 - Inspect the board for joint cracks; the components labeled C tend to be most prone to cracking. A crack is pictured below - some cracks may be more faint and difficult to spot. Check the entire board thoroughly as often more than one crack will be present.
Step 8 - Touch each cracked solder joint with a hot soldering iron; if the hole vacates after being touched then carefully add more solder. Radioshack sells fine solder spools that are easier to manage on tiny components.
Step 9 - Reinstall circuit board to case. Remember to squeeze the fat sides of the board does not slide in smoothly. Don't force it.
Step 10 - Plug cruise control module back into vehicle and leave dangling. I recommend a quick test drive to confirm the cruise control is again functioning. Do not have passengers in the vehicle with your passenger side dash apart.
Step 11 - After confirming cruise control function, remount module and reassemble dash/glove box assembly. Alternatively if the cruise control does not function then it may be worthwhile to check the board again for cracks and repair as necessary.
Step 12 - Enjoy cold beverage of choice, high-5 self.

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Re: Cruise Control Repair - 80's & 90's Modules

Postby kompressorgolf on Jun Fri 25, 2010 9:17 am

hnmmm i wonder if this would work for mk3's? dont see why not, ill check this out. Andrew, your DIY's are always great :thumbsup:
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Re: Cruise Control Repair - 80's & 90's Modules

Postby Mikewire on Jun Fri 25, 2010 9:49 am

Agreed, nice writeup - moved to the DIY section. :thumbsup: :beer:

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Re: Cruise Control Repair - 80's & 90's Modules

Postby DieGTi on Jun Fri 25, 2010 12:36 pm

Thanks - Yep, should work the same on mk2/mk3 vw modules. Much cheaper than a new one! :)
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Re: Cruise Control Repair - 80's & 90's Modules

Postby kompressorgolf on Jun Fri 25, 2010 12:38 pm

yeah and the new ones do the same damn thing, we put in 4 different ones at the dealer here for a guy and they all malfuntioned in a week finally, the guy said to hell with it! wish i knew about the re- soldering trick back when i was a tech :)
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Re: Cruise Control Repair - 80's & 90's Modules

Postby DieGTi on Jun Fri 25, 2010 12:44 pm

My understanding of the failure is thermal expansion of the joints due to natural environmental conditions. There are pretty wild temperature swings up here so you may see more of these units failing than areas where the temperatures are more moderate. 4 times, that's pretty tough luck.
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Re: Cruise Control Repair - 80's & 90's Modules

Postby MT-Getto on Jun Fri 25, 2010 3:04 pm

The relays fail in those too. I tried the re-solder on several MK3 units to no avail :(
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Re: Cruise Control Repair - 80's & 90's Modules

Postby Rennwagen1 on Jun Sun 27, 2010 10:02 pm

Mine also does not work. I may have to try this. That is the one thing that drives me nuts on the Jetta, foot cramping.
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