1995 - 2002 GM OBS Truck Cruise Control Thermal Disengagement Repair (Chevy & GMC)

[@ED-ti5tc]

I went to the salvage yard to get another one. I kept my original one. Great video! Thanks

[@triptheroad]

Mine has about a 50/50 shot of working, will cut off randomly while driving too. I've already replaced the brake switch so I will try to reflow the board next, great idea! Can't seem to get conditions that it is consistently replicated but I've tried manipulating the brake pedal and multi function switch while it does work and that doesn't have an effect.

[@erichwise7734]

As always an excellent video. Would potting help sustain the board, or retain more heat?

[@DrShock]

Thanks. Due to the electro-mechanical aspect of the module resulting in an open space requirement, potting would not be possible. But the board was sprayed with a clear _conformal coating_ for protection from the elements originally by Delco.

[@creverett9]

@@DrShock Which coating did you use?

[@DrShock]

I did not need to re-apply any coating as the solder reflow did not sufficiently disturb the factory original one to be a concern.

[@creverett9]

Hi I have a question, say you weren't able to notice any physical disrepair to the board (for example cracked solder joints, bad capacitators, broken traces) how you you more forward in diagnosis to make a repair to the component? I am interested in trying to learn how to repair electronic modules and am curious what could be done to learn how to fix. I have the original Delco radio out of my 2006 Silverado (I've since replaced it with a more modern touchscreen pioneer head unit) but I've always wanted to fix it and maybe reuse it for like a shop radio but i cant find any damage to the board so there's likely a failed component somewhere (concern was no sound out put all other functions normal)

[@DrShock]

It's really not cost effective to do board level repair on a three decade old automotive module. Especially since many, if not all, of the ICs Delco (and later Delphi) used are going to be proprietary and _unobtainium_ commercially. For something _easy_ you could test for shorts to ground on the capacitors and resistors, and you could do a diode test on each of the diodes and transistors. You could test for continuity to voltage and ground at each of the ICs (presuming you could determine the pinout in the absence of a datasheet), each leg of the harness connector, and each of the bridge connector pins. But I'd say that's about it, and I wouldn't even go that far when you can just pop in a replacement from the salvage yard for $15 or so.

[@Milkmans_Son]

Would it make sense to put a small dab of Superlube Synthetic on those gears (Delrin or whatever they are)?

[@DrShock]

Something non-petroleum based, safe for nylon based materials could be ok. I chose to leave it be as there did not appear to be any applied originally as well as no cosmetic signs of wear present.

[@josh_a58]

How much do those cruise controls vary? Aside from 88-94 and 95-98? Is there a way to determine if the box is bad or if it’s the stalk switch?

[@DrShock]

The GM service manual has a fairly extensive diagnostic tree to determine the root cause of problems with this vintage cruise control used from 1995 and up GMT400 trucks. It's mostly going to involve electrical and signal diagnosis.

[@timhannon1959]

Do you suggest replacing the whole module if you have no cruise at all?

[@DrShock]

Not necessarily, you would need to do further diagnosis to identify the root cause of failure. It's _uncommon_ that these modules go completely bad on these years. They are very robust. Checking for wiring harness issues (no power, no ground, no signal, etc), fuses, or control switch issues on the steering column first would be the advice.

[@brettbarber7172]

so my 98 gmc is having the opposite problem, the cruise will not work if it's cold out or until the truck has been running for a few miles. Before I tear it apart, do you think it's possibly the same issue? Thank you for any reply.

[@DrShock]

If you're saying you have trouble free cruise controlled driving during the _entire_ Summer, but consistently interrupted cruise during the _entire_ Winter (the two extremes of hot and cold) that would not be the same root cause as I went over here. For that kind of behavior I would first inspect wiring harness plugs at the module and column switch and reseat them. If the problem persisted with the wiring checks completed, only then would I resort to replacing the module or it's internal circuit board.

[@brettbarber7172]

Thank you.

[@Tomcat71]

I have a 91 and the cruise interferes with the ignition .. causes the ignition cut out like you just turned the key off and just blew up the new muffler I installed.

[@triptheroad]

sounds like you could have a bad ground or connection somewhere in the engine bay and engaging the cruise control is causing the voltage potential to drop to zero

[@mitchc491]

I’ve got a 1994 GMC K2500 4x4 5.7L 4L80E. Cruise control issues. With the key turned on, I don’t have 12v to the gray wires going to the cruise control module. Where does the power come from?