[urq] A4 content

[Reggie Forster]

I've experienced similar problems with a 2001 Tip S4.  Only once did I 
have a complete failure, as you described; in that case, turning off 
cruise and the ignition the restarting cleared it.  I've never seen a 
related DTC error and have had the cruise switch/stalk replaced.  It 
seems to be more prevalent when I have the APR ECU/chip installed - I 
thought that was the root cause, since APR controls the ECU program 
mode via the cruise control.

         reggie


On Jan 16, 2004, at 3:26 PM, W. Bremer wrote:

> Forgive the A4 content, my urq is resting is a heated garage for the 
> winter, so I get to play with my daily drivers....
>
> For you A4/A6 owners out there, any thoughts, comments, opinions???
>
> Over the past 5 months, my 1998 1.8T A4 with Tiptronic (now with 68K 
> miles), has suffered from erratic cruise control behavior:  It would 
> not engage, or if it did, it would self-disengage without warning 
> after 5 or 10 minutes.  When it would engage (from pressing the "set" 
> button), I could hear the faint "click" sound from the control module 
> above the glove box.  With the help of Bill Bennett and the Bentley A4 
> CD, I checked out the various systems as best I could (without pulling 
> the air-bag steering wheel to check the switch in detail) to see if I 
> could find an obvious problem.  I checked all the connections for 
> contact and cleanliness, and also circuit continuity for those I could 
> access, and sprayed some electrical contact cleaner stuff into the 
> cruise switch on the stalk, etc., etc., to no avail.  I even opened up 
> the control module looking for bad solder or a burnt component).  
> Sometimes it would work briefly, but most often I could press the 
> "set" button on the stalk but the control module would not engage the 
> system.  The two brake slight switches were firmly mounted and held 
> vacuum or controlled the electrical circuit correctly.  Following 
> Bentley, I confirmed that the hose and actuator vacuum system held a 
> vacuum.  In a nutshell, I was unable to reliably get the system to 
> engage under all sorts of speed and button-pushing situations.
>
> Yesterday evening, in the -10F temp, the car's battery was too weak to 
> spin the starter fast enough to start the motor, so my wife got a 
> "battery boost" from the security folks where she works.  Whether from 
> a big drop in voltage (from then initial cranking effort) or a voltage 
> spike from the successful jump start, two things happened: (1) the 
> radio went into "SAFE" mode, easily corrected, and (B) today (in +4F 
> temps), over the course of 2.5 hours of highway and local driving, the 
> cruise control performed flawlessly, even as I deliberately mucked 
> with it to see if I could get it to fail under controlled 
> circumstances.  (In the past, such "mucking" (disengaging, 
> re-engaging, resetting with new speeds, etc.) guaranteed a 
> non-functioning cruise system.
>
> My suspicion is that the voltage drop or possible spike somehow 
> affected something (presumably the control module).  Has anybody else 
> experienced this sort of cruise control behavior?    Any thoughts as 
> to what might have been causing the recent system failure?
>
> Thanks,
> Bill
> '82 urq
> '85 4KQ
> '86 5KCSTQ
> 98 1.8T A4
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