86 yr old shadetree knuckle buster.

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Old MXer

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Found you guys while Google searching for "94 Silverado Cruise Problem " or something similar to that...
memory is the second thing to go!
In 2007 I accidently bought a 94 K2500 HD, 5.7, L80, 4x4, extended 2 dr & long wide. Nice clean truck in every way. Ran & drove great. But, I bought it off of the dealers "BackLot" with a "BackLot" price, so I figured it would have a surprise or two waiting for discovery. It did, but still worth the money. It's done every thing I've asked of it & I've returned likewise. I plan to keep this partnership until one of us dies. So far we're running neck & neck.
Anyway, I've searched the site for awhile & can't find what I'm looking for even though I'm sure it's on here.
The cruise control intermittently fails in about every way I can think of. The only failure that is consistent, every time, solid failure, is while going downhill steep enough that the cruise decides to back off the throttle. After the hill, back on level ground again, it forgets to resume. Pressing the resume slide or the set button gets nothing. Switching it off & back on restores normal operation until the next downhill or one of the other failures occurs.
Can someone get me to a thread that addresses troubleshooting this problem?
 

thinger2

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Found you guys while Google searching for "94 Silverado Cruise Problem " or something similar to that...
memory is the second thing to go!
In 2007 I accidently bought a 94 K2500 HD, 5.7, L80, 4x4, extended 2 dr & long wide. Nice clean truck in every way. Ran & drove great. But, I bought it off of the dealers "BackLot" with a "BackLot" price, so I figured it would have a surprise or two waiting for discovery. It did, but still worth the money. It's done every thing I've asked of it & I've returned likewise. I plan to keep this partnership until one of us dies. So far we're running neck & neck.
Anyway, I've searched the site for awhile & can't find what I'm looking for even though I'm sure it's on here.
The cruise control intermittently fails in about every way I can think of. The only failure that is consistent, every time, solid failure, is while going downhill steep enough that the cruise decides to back off the throttle. After the hill, back on level ground again, it forgets to resume. Pressing the resume slide or the set button gets nothing. Switching it off & back on restores normal operation until the next downhill or one of the other failures occurs.
Can someone get me to a thread that addresses troubleshooting this problem?
Welcome to the forum. I was just out in the garage in front of the heater whining about working on my truck and I just turned 58.
I am am happy as hell to see that I can maybe still turn a wrench at 84.
I really cant imagine not being able to and that is my biggest fear.
I do not know much of anything about the cruise control.
My 94 K2500 has never worked but I dont care.
Do you have any issues with your headlights or turn signals or 4 ways?
Are the dim or do they flicker at all?
That entire multi function turn signal switch and the headlight switch are grounded at the same place.
If so, there is a ground wire underneath the dash right behind the OBD1 port that bolts to a bracket that always rusts.
You can pretty much look for the rusted bracket first and then find the wire that bolts to it.
I would start with cleaning that ground .
It is worth a shot.
Good luck and if that doesnt work everybody here will help to figure out what it is
 

Old MXer

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thinger2 Thanks for the welcome & for the ground tip.​

With the intermittent CC problems going on, I have considered bad grounds & have been meaning to give all the grounds some attention. I'd have never found that one.
Relating only to the one solid failure I have, leads me to think that it's maybe not ground related. (I've learned the hard way to always fix the solid or obvious problem first, even if it seems unrelated, if it's electronic in nature.)
Some things I've done: I replaced the turn indicator arm containing the CC controls. I could see some slight voltage variation when abusing it so I shot a little contact cleaner into the CC contacts. The label on the can of contact cleaner mentions in small print that it's possibly harmful to some plastics. I proved their point. Anyway that's one thing that isn't causing the problem. The brake switch meters out ok plus I've beat it up pretty good while driving & can't make the CC drop out. I'm leaning towards the CC module at this point. I've touched up the solder joints (twice) to no effect. Anyway I'm hoping it's the only thing that's smart enough to forget what it's doing when going downhill...
 

Old MXer

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Hey Tayto,
I did replace the lever that you suggested. Unfortunately it didn't fix my most obvious problem. It could have fixed some of the intermittent problems though. Time will tell.
I'm looking for a cruise control module plus the box it sits in. The box lid screws were corroded in, & Blaster didn't help. I twisted three of them off. I'm hoping to find a good box & unlikely, but maybe, a good module in it.
If you or anyone else has info on which trucks, & maybe cars, used the same module as my 94 Silverado please let me know. I'll be hitting the junk yards on monday.
 

movietvet

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Welcome to the forum from Oregon.
If the module box is that corroded then the connector(s) may be too. Pay close attention to that.

Try this place for used parts: https://www.car-part.com/index.htm

After close to 40 years in shops as a tech and then manager and before that time and after in my driveway, I hope I can still turn a wrench when in my 80's. At 71, I still do for a little extra money and sure as hell miss a lift at times.
 

thinger2

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@thinger2

Sorry, I forgot to answer your question about the headlights. They have no issues. I've recently replaced the old headlight enclosures & changed to LEDS. Also modified wiring so dims stay on when brights are on. What a difference! All is good there.
If the LEDS are working good I would think that that means your grounds are good.
I would still a good look at all of your ground wires.
Even the battery cables.
They are well known for looking perfect on the outside but being rotted underneath that plastic end.
These TBI systems are very basic and very voltage and ground sensitive.
I also seem to recall that the circuit for your transmission may run through your brake light switch.
And that could affect the cruise control.
Do your brakes lights flash or shut off when you hit the pedal?
Try it when it is off and try it again with it running.
I dont want to lead you down a path but I am really thinking you have a bad brake light switch.
Hopefully some other folks will get in to this but that switch is a pretty commen failure
 

Old MXer

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If the LEDS are working good I would think that that means your grounds are good.
I would still a good look at all of your ground wires.
Even the battery cables.
They are well known for looking perfect on the outside but being rotted underneath that plastic end.
These TBI systems are very basic and very voltage and ground sensitive.
I also seem to recall that the circuit for your transmission may run through your brake light switch.
And that could affect the cruise control.
Do your brakes lights flash or shut off when you hit the pedal?
Try it when it is off and try it again with it running.
I dont want to lead you down a path but I am really thinking you have a bad brake light switch.
Hopefully some other folks will get in to this but that switch is a pretty commen failure

Thanks for the suggestions. Using them here's the plan:

All ground wires are on my punch list. I'm not overly concerned right now, but that could change depending upon the outcome of the "Downhill" problem after replacing the CC module. (It would be great to hear from someone who has had this problem.)
Battery cables are accessible so I'll check them tomorrow.
I'll hang a meter on the cruise control circuit of the brake switch output & look for any voltage variation while driving with cruise on.
No indication of TBI problems by seat of the pants diagnostic procedure.
What would the tranny symptoms be that I could watch for?
I'm pretty sure that the brake light circuit is solid but I'll check it using your suggestions. The story is: A while back I was blowing brake fuses. Sometimes they'd last a day or two. At other time they'd blow before I'd get out of the driveway. Drove me nuts until I finally found an intermittent short in a major cable assembly that runs across the firewall directly behind the intake manifold. It hadn't been routed correctly & was brushing against the manifold. Heat & vibration had worn through the insulation of both the cable & the brake circuit wire. When conditions were just right, it would short.
The reason that I'm centering on the cruise module at this point is the 'downhill' failure. This fails 100% of the time. It just takes enough of a slope to cause the cruise to back off the throttle. Then it fails to automatically resume. Both the resume & the set switches get no response until I switch the cruise off & back on. (Good 'ol POR) Then all cruise switches work & cruise is good until the next downhill or until one of the intermittents shows up. I think if I can fix this problem it may (or not) fix other intermittent cruise problems. The module could be responsible (or not) for all of it.
 
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