'76 C30 Cruise Control Help...
 

Hi. I am in need of some assistance diagnosing the cruise control on my '76 C30. It has worked perfectly ... three times...in the short time I have owned it. That tells me that the issue is likely something simple???

It has the single button actuator on the turn signal post. Simple on / off only. No resume, accelerate, etc.

There is a switch down by the brake pedal that I believe is part of the cruise. It has a vacuum line to the switch. The switch makes a hissing sound when the brake is engaged and no hissing sound when the brake is not engaged. (that makes sense to me)

The vacuum hissing sound at the switch by the brake pedal does not happen all the time when the brake is applied, but I feel like it should...??

The vacuum lines show no signs of leaking.

If anyone can provide some insight on what they think and how to test, I would really appreciate it. The cruise is the only thing on this truck that doesn't work properly and I want to get it dialed in.

Thanks in advance!

Re: '76 C30 Cruise Control Help...
 

Not an expert but that vacuum switch is designed to dump the vacuum in the pot holding the throttle open when the brake is applied. Very likely that if the cruise isn't engaged, there is no vacuum to dump, thus no hiss.

I think some cruise systems also had a 2nd electrical brake switch that cut power to the cruise unit to turn it off. If you have one and it is not adjusted correctly, might not let the cruise turn on.

Re: '76 C30 Cruise Control Help...
 

Download the Cruisemaster manual in the manuals post.

Re: '76 C30 Cruise Control Help...
 

Thank you, I will look into that. That would be very helpful!