sheepers

The cruise control on my 99 2.8 does not engage at all. From reading the archive, the problem can either be the vacuum system or electrical system.

If I don't hear the cruise control relay clicking from the glove box area, does it rule out the vacuum system?

Engage

2.7TnOKC

Interesting...mine never cicks.

nm3210

I've got the same car, so I know what you're talking about. The clicking appears to sound from the middle of the dash and that is fairly accurate, the module is behind the glove box on the left hand side (so from the drivers seat it sounds like it's almost coming from the hazard relay). I had cruise problems for an entire year before finding a fix that actually worked.

Does it occasionally work (like every 1/40 or even 1/100 times?) because that's how mine started - it basically got steadily worse since i've acquired the vehicle a year ago. It really got bad when my car started doing extreme hot/cold cycles, which happens when you live in a cold climate and drive the car until it's warm. What I would suggest is you try this fix first: https://www.audiworld.com/forums/sho....php?t=1728645 It has completely cured my cruise and it works 100% now, which has been really really nice (only the LCD screen and a cup holder to make it like new again!).

I am 95% sure that if you fix the cruise control module it will fix your problem. I will say that there is a chance that the cause is from something else, but this really is the simplest way of fixing it.

Here is a rough walk through:
• Remove glovebox
→ unscrew bottom two screws (8mm socket i think, could be 7 - NOT slotted, however)
→ open glove box and remove top three screws(same size)
→ slide glove box out (towards rear)
→ set gently down on mats/floor

• Remove cruise control module (has 5GA-004-397-16 on it):

→ remove the two 10mm bolts (could be 8mm for some)
→ remove the wiring harness and pull out module, should look like this:


Now with the module in-hand you can fix it:
• Remove aluminum housing
→ fold back the four aluminum 'tabs':


→ pry out black faceplate (it's separate)
• Find and label joints to resolder (if you want)
→ the cause is the three red capacitors:


→ resolder the joints from the back (mine are black from a Sharpie marker to help show you guys):


Reassemble and enjoy your working cruise! If it doesn't work, then....it's probably caused by something else.

edit: last updated July 5th, 2010

sheepers

Cruise control does not work at all.

I plan to being by investigating the electronic side of the system too.

Start with measuring the harness resistence to make sure the stalk is working, and then open up the module to check the solders.

Thanks.

sheepers

I'm happy to report that NM3210 nailed the problem.

I removed the glove box and confirmed my stalk switch was working with a multi-meter (be sure to put auto trans to D to feed power to the module).

By glancing at the circuit board, I didn't notice any defect; but under a bright light, I noticed a ring around one of the the red capacitor soldier joints.

I resoldier the all the red and blule capacitors,and the module "clicked".


Thanks guys.

a6hcw

If resoldering does not work on cruise control module 4D0907305, then you could have a bad power transistor T7 (ST #BD535), which is located next to a large electrolitic capacitor and is embedded in white mastic material. This transistor is available from www.digi-key.com where you may download a datasheet.
http://search.digikey.com/scripts/Dk...=497-8437-5-ND

Airbag

should the relay cleck as soon as you turn the cruise on or only after you try to set the speed ?

my cruise does not work and i took my moddule out and found it a lttle different with new style caps. i resoldered anyway to no avail . I also have a 2000 A6 ( currently working on my Audi 90 ) with mechanical cruise so i am going to se if i can find the same module and swap it. any one know how to get to it on the 2000 a6 ? i took the glove box and the drivers side tray out with no success

thejulex

That's a hardcore fix right there, I love this thread.

Airbag

Yeah but the problem is I can't find the stupid module on my 2000 A6 i took the glove compartment right out and it wasn't there .. just an airbag .. then i took the drivers side cover off .. nothing there either ... this is sooo frustrating ..

Airbag

Yeah but the problem is I can't find the stupid module on my 2000 A6 i took the glove compartment right out and it wasn't there .. just an airbag .. then i took the drivers side cover off .. nothing there either ... this is sooo frustrating ..