Giving this a bump, as that worked well for me last time. I'm loathe to believe nobody has any ideas or experience on this, and my lack of cruise control is really annoying.

 

Are you sure the CEL is the cause for nonfunctional cruise control? The systems are notoriously fickle and have issues with the pump, the vacuum lines, the vacuum capsule, the brake pedal switch, and the ECU

I hadn't heard of the CEL being cause for disabling cruise before this

 

TBH I'm not sure, but I've pulled my pump and it is working just fine. The vacuum hoses are fine, I just replaced the actuator diaphragm (and made sure it holds vacuum). I just read somewhere that if your CEL is illuminated, cruise control is disabled by default, so I figured if that's a known issue it's the first thing to tackle. Can anyone confirm that a CEL will disable cruise control? Does anyone's cruise work with their CEL on?

 

from etc manual page 80

CEL disable of cruise control only applies on 300 Tdi's.

 

I'd put money on a bad ecu. I don't even bother reselling the DI ECU anymore. Too many failures. Remove the ECU, it's a silver box about the size of a cigarette pack, behind the glove box. Open it up and inspect the circuit board for bad solder joints and other issues. People have been swapping in the DII cruise control ECU as a mod to get their system working again.

 

Listen to Paul. He knows about these things. FWIW I did exactly what he describes (IIRC I purchased the new cruise ECU from him) and it now works perfectly.

It is worth replacing the vacuum hoses as well. They are cheap.