I just picked up my 100s ( 156k miles ) runs great, and the two problems ive found is the cruise control isnt working and the emission light stays on.

I know very little about audi's but wanna learn, can someone give some advice on where to start on these two problems. I did a search but didnt find much info at all....

 

I think the 93 used VAGcom diagnostics - but in any case you'll need to pull the codes to figure out why the CEL is on --

 

The cruise not working is a very common problem. It doesn't work on mine or anyone else I've talked with. I've heard of some people buying their cars, finding it works, and then 5 minutes later it stops working. I've not looked into it yet, but when I do I'll let you know.

 

My cruise control did not work for almost a year until I replaced the Cruise Control Switch/Pedal Vacuum Valve Switch. I drove home today and thought I would give it a try and almost jump for joy at 60 MPH on the interstate. You'll find it after removing the covers on the driver side just above the brake pedal. Check it, it might be bad or loose. Mine was both. I found one in a junk yard but you can get one at www.autohausaz.com for about $35. I'm not promoting the site but they have a nice picture to compare it to.

 

The cruise switch contacts in the turn signal stalk get dirty. Spray the switch with electronics cleaner. Really soak it. Do that a couple of times and go for a drive. Did that fix it? If not, next likely candidate is the cruise control module. Located behind the glove box (silver module). The relay inside that module should click when the cruise engages/disengages. If it's not clicking, remove the module and replace from a junk yard. Or, you can open up the module (carefully) and resolder the joints around the relay. That usually makes it work again. Reinstall the module and go for a ride. How's it working now?

Detailed diagnostic info here: http://forums.audiworld.com/a6100/msgs/93827.phtml
and module repair info here: http://forums.audiworld.com/a6100/msgs/93989.phtml

 

thank you !! for all the info ill try and work on the cruise and let you guys know how it turns out.

 

My cruise control is extremely touchy.. you might have to try a couple times to set it, but it works.. while your driving down the road.. try to set it a couple times.. it'll kick on eventually.. you just have to work with it.