Cruise Control should not be an oxymoron

[MrEdd]

Is it normal for my cruise control to be finnicky? I think that the older diesels just have that tendency to baulk the cruise control. What my truck will do, however, is drop out of cruise completely, generally at highway speeds between 70+mph. Is it because the computer sees the engine speed increase as too great? The truck is the '98 in my sig for information.

[Cowracer]

Is it normal for my cruise control to be finnicky? I think that the older diesels just have that tendency to baulk the cruise control. What my truck will do, however, is drop out of cruise completely, generally at highway speeds between 70+mph. Is it because the computer sees the engine speed increase as too great? The truck is the '98 in my sig for information.

there are a few codes that will not light up the SES light, but will cause the cruise to drop out. Pull your codes and see what you got.

Tim

[JohnC]

It will drop out of cruise if the PCM sees anything unexpected with fuel solenoid closure time. Often this is a precursor to stalling related problems and fuel solenoid or FSD problems.

[gmctd]

The brake switch will cause that, also - if not adjustable, will need replacing.

If that doesn't cure it, then JohnC's prognosis is high on the list of probabilities

[JohnC]

The brake switch will cause that, also -

Oh, yeah, right. Forgot the easy stuff.... :o

[restoguy]

Here's another idea. Check out the control stick. My '94 was having cruise problems and I was convinced that it was the computer that was causing it. But the guy at the local parts store said it was probably the stick.(The guy at our parts store isn't the typical 19yr old drop out that can barely read the computer screen down at the 'big chain' parts store. He's run this family owned store for 25+ years!) I got a new stick and plugged it in(under the dash at the bottom of the steering column), set the stick in my lap and took off down the highway. After trying everything I could think of to make the cruise screw up, I decided he was right. Then I took the old stick out and replaced it. If it hadn't worked, I would have just retruned the 'expensive test euipment'(new stick) and not been out anything. Some parts stores are nicer about taking parts back than others. I'm lucky.

P.S. If you do decide to change the control stick(blinker arm), tie a piece of decent string to the end of the cord when you pull it out of the steering column. Then, when you put the new one in, you just tie the end to the string and CAREFULLY pull it through. No fishing or disassembly!

[rustyk]

Oh, yeah, right. Forgot the easy stuff.... :o

I had the same problem on my motorhome - the brake switch was a tiny bit sticky, and that cured it.