cruise control problems

[6 and 1/2 liters]

Hi I was wondering if any of you have ever had any problems with your cruise controls. Sometimes on my 97 s code I will start it up and head out to the highway and try and set it and will get no response at all from it. If i keep trying to set it, it may work for me a few miles down the road. And sometimes i can jump in and set it right away and then out of the blue 60 miles later will kick off. It then will not reset for a couple miles again. Are these entirely controlled through the ecm? if anybody has any ideas i would love to hear them. thanks

[BILLYDIESEL]

your brake switch is probbably out of adjustment or loose

[Cowracer]

also, some codes that wont set the SES will disable the cruise.

I'd pull codes to see whats in there.

Tim

[Robyn]

This sounds like very good advice to me.
Check the brake switch first.
" A twinky little trick here" Hook one of those funky cheap Bungy cords on the brake pedal arm and hook it up around the column to keep the pedal back against the switch hard. This is quick and requires little time. If this works you know the trouble is in the neighborhood and you can then wiggle under the dash and either replace the switch or adjust it. If this proves futile an examination of a codes would definately be in order.
The older Gas rigs had vacuum switches on the brake switch assembly too and they would sometimes get stuck open. The diesel is all fly by wire and only has a safety switch on the pedal to cancel cruise upon application of the brakes.
I remember a trip to So Cal a few years back in my dually. We stopped for fuel and the brake lights would not go out. The switch was messed up and could not be adjusted, if I held the brake pedal back slightly the light would stay off. A trip into the next truck stop a a couple $$$ had a package of those funky little bungy cords and one hooked to the pedal. That thing was there for about 6 months before I finally took the time to get a new switch and fix it.
Typical mechanics attitude, if its working "Leave it alone"

[MTTwister]

It would randomly drop out, and not re-set. The GM dealer had it for a few days, and it finally did it for one of the techs, as he was crusing down the road and hooking up his scanner. I told them to be sure there weren't any big rigs behind them 'cause if they weren't paying attention, the outfit would be a hood ornament.

They replaced the IP( warranty) , and "problem" solved. ( of course, they had to replace the lift pump, too, naturally.)

Anyhooo - don't know why, but it could be another possible source. I like the above options better, tho'. Hope one of those cures it for you.

[6 and 1/2 liters]

I tried keeping the pedal back but still had a failure. I havn't pulled codes yet but hopefully will this weekend. Also are you sure it was the pmd and not a failure in the pump itself. I have heard if the optical sensor detects a miss it will kick the cruise off. Will post back with code results. thanks for the tips so far.

[MTTwister]

Well, no. Naturally they replaced the whole package, but at @36,000 mi I've been under the assumption ( self delusion) that the PMD had pooped out.

[6 and 1/2 liters]

well the only codes I had were 2 for the egr system. Those codes are always present because of my f code plenum on my s code. So I guess if its not the brake switch its likely the pmd or the pump itself.