aftermarket cruise control - Rostra

[iterate]

Hi, my 2003 Corolla CE has an aftermarket cruise control installed, Rostra model 250 1223. This model year is *not* drive-by-wire so the cruise module actually has some cords that physically control the throttle under the hood.

It was installed in 2002 shortly after I bought the car new, worked for a few months, then quit. I went back to the installer to have it fixed a couple times but it kept quitting, eventually I gave up.

I'm preparing for a cross country road trip now and it would be great to get it working again.

The symptoms are that it simply doesn't respond to any controls. On, off, set, resume, accelerate, nothing works, it might as well not be installed at all. To me this sounds like some sort of wiring problem.

I'm not an electrician or mechanic so I was trying to find a shop that might repair it. The shop that originally installed it is a couple thousand miles away and has gone through two buyouts and management changes since, so they're no help.

The audio install shops refer me to mechanical shops as they are iffy on cruise control; but I don't think it's a mechanical problem. I don't want to pay them a $120 diagnostic fee just to have them say they don't know how to fix it.

I downloaded the manual for the cruise module and troubleshooting seems to require some serious electrical knowhow and diagnostic tools.

Any advice? How can I find a shop in the SF bay area or LA metro area (I go between both) that might be able to help?

Thanks in advance...

[iterate]

Update.

I suspected it was a simple wiring/electrical problem since the cruise didn't respond at all. If it responded but some features didn't work correctly, or something, I might think it was mechanical, but that wasn't the case. Electrical digital stuff is usually all or nothing; it's the analog stuff that has varying degrees of operation.

So I skipped the mechanical shop that wanted $120 just to 'diagnose' it (along with the rest of the car) and went to a privately owned audio install shop (i.e. the electrical guys) who said he'd take a look.

Turns out it was a blown fuse. So simple! But being a noob I wouldn't even have known where to look for that. He showed me the fuse location under the dash and only charged me $50 for his time.

Just tested it on the way home and seems to be working fine now -- after five years of being dormant! Crossing fingers it holds up this time.