2005 Prius intermittent cruise control problems

sounds like a loose connection, but it could just be a bad stalk. any codes?

 

Try to pressing the cruse on button while turning the steering wheel to different positions. Do this stationary of course. If it works in some position but not others it probably faulty spiral cable that goes to steering wheel. Other vice it is probably bad stalk.

 

As previously suggested, either the cruise control switch is getting flaky or the wiring to the switch has a problem, in particular the spiral cable in the steering wheel.

Are any warning lights on? If not, then there won't be any diagnostic trouble codes to retrieve.

 

Yes

 

be very careful of the airbag. there are some clock spring threads here.

 

One of the Toyota dealers that sell parts at a discount over the web, for example:
Toyota Parts - Genuine Accessories | AutoNation Toyota Gulf Freeway Parts

 

First go to this site with your VIN and get the right part number. There are at least two different options for my model year, I found out. (On that link, look at part no 84306-xxxxx.) If your car has VSC, you'll have to move the VSC switch from the old housing to the new, a few minutes dealing with plastic snaps. It's an easy job if you can follow proper SRS precautions. I didn't even need a puller for the wheel. You'll need a Torx driver to remove the air bag.

Have you noticed the air recirc switch on the wheel doesn't work any more? That was my first indication the cable was failing. The cruise was second to go.

It's commonly called the clockspring. That'll help you find the threads that I used to changed mine out.

 

Clock spring?

 

yes, clock spring. i know, right? lots of threads though. the first time i saw it, i thought it was a joke.

 

Yep, that's it and that's all you'll need. You may have noticed cheap knock-offs are available on eBay for around $25, shipped from China. I went that route and it's worked fine for me. Others have reported high failure rates and recommend getting the part from the dealer. It's hard to argue with that since the worst case failure mode could leave the DS airbag out of service for as long as you have to ignore the warning light.

I noticed poor pin quality (on the accessory connector) on the one I bought, and had to straighten one out to make contact. But the SRS pins and terminals looked identical to the original, and there are redundant SRS cables in there, so I feel pretty confident about the life safety aspect and it's been working fine for nearly 25K miles.