97 Tahoe cruise control unexpected disengaging - SOLVED

[Tahoe97]

Hello forum friends. Back here with another issue with my 97 Tahoe 4x4 5.7. This weekend while crusing along at around 65 mph with my cruise control engaged, the gas pedal suddenly released from its holding position and the cruise control was no longer holding my speed. I was unable to re-engage the cruise until about 20 or 30 minutes later on the trip when I was able to set my speed and the cruise would hold. This engage followed by unexpected disengaging continued through the weekend and seems to be a new issue. I am assuming my Electro Motor Cruise Control module is failing but I suspect a brake pedal cruise disengage switch malfunction could also be the cause. Any guidance here is greatly appreciated. Pictures of the cruise control module are attached. Thanks

 

[Eman85]

Brake light switch is a lot cheaper. I'd try and hook a test light of some sort to the brake light circuit and monitor it when driving. A scan tool will show you that also if you have one that reads live data. Turn signal switches are known to fail also.

 

[Tahoe14]

@OR VietVet may know

 

[OR VietVet]

@Eman85 is on the right track. Start with the simplest source first. Even though modules fail, they hardly ever do unless they are exposed to extreme heat or water or mounting problems or filth or or or....The brake switch is inexpensive and a known intermittent source of cruise control problems. I would also inspect the throttle body area for linkage and cable problems.

 

[Tahoe97]

Thanks, I'll swap out the brake light switch first and see if that resolves it.

 

[Eman85]

The switch is a pain to swap, hooking a test light up is simple. On my K2500 I found a terminal by the fuse block that had brake lamp power, easy to access.

 

[Tahoe97]

My brake lights work fine so I suspect some component in that switch that turns off the cruise may be malfunctioning. We'll see.

 

[YukonGTmaster]

The Multifunction switch/Turn Signal stalk can cause a myriad of problems. Cruise control, turn signals stuck on, brake switch issues. Ask me how I know.

 

[exp500]

Cruise boxes also known failure items. But it's best to eliminate other possibilities first. They are a pretty much junkyard only item.

 

[Tahoe97]

I ordered Brake Light Switch ACD#1565E/GM#93801734 from Summit Racing with a new identical retainer clip from the Dorman GM Brake Light Switch Retainers 6 pack #13808 (Advanced Auto). It was a royal pain in the you know what to navigate tools, hand, switch, and retainer up above the steering column and remove the existing retainer clip and swap out the switches and install a new retainer clip. I managed to get it done, tested the brake lights and then took it on the highway to set the cruise which worked as designed. The test now comes over time to see if the cruise stays engaged on an extended drive. With 27 years and 238,000 miles on the original switch, the switch replacement may have been the solution. Thanks for the input!

 

[Eman85]

Replacing those switches are a true test of patience and can enhance your vocabulary.

 

[Tahoe97]

Replacing those switches are a true test of patience and can enhance your vocabulary.

Yes, my vocab was fully utilized as I tried over and over and over to get the existing retainer clip to release and then again over and over and over to get the new retainer clip on, without having any space to put my fingers on the retainer clip at all. I must have dropped the retainer clip at least a half dozen times before getting it to stay in place, and then had to press it in, which took several attempts at a minimum. On top of this was the issue with the wiring harness being too short to allow me to put my eyes on the switch while I attempted to attach the connection. I had to attach the connection virtually blind. Persistance won out.

 

[Tahoe97]

I ordered Brake Light Switch ACD#1565E/GM#93801734 from Summit Racing with a new identical retainer clip from the Dorman GM Brake Light Switch Retainers 6 pack #13808 (Advanced Auto). It was a royal pain in the you know what to navigate tools, hand, switch, and retainer up above the steering column and remove the existing retainer clip and swap out the switches and install a new retainer clip. I managed to get it done, tested the brake lights and then took it on the highway to set the cruise which worked as designed. The test now comes over time to see if the cruise stays engaged on an extended drive. With 27 years and 238,000 miles on the original switch, the switch replacement may have been the solution. Thanks for the input!

Well the celebration was short. Took the Tahoe out this morning and the cruise wouldn't engage. So that rules out the brake light switch as the cause. I understand there can be mechanical failure inside the Electro Motor-Cruise Control unit that is attached to the firewall directly in front of the driver. After almost 28 years and 240,000 miles, and lots of use of cruise control, maybe that is what is going on. The search continues to rectify this.

 

[Tahoe97]

SOLVED: Replaced the cover/control board inside the Electro Motor Cruise Control module with a used cover/control board of the exact same Electro Motor Cruise Control model # purchased off E-Bay and the cruise now works properly. So it appears that the issue was a failed control board.

 

[exp500]

Replaced the cover/control board inside the Electro Motor Cruise Control module with a used cover/control board of the exact same Electro Motor Cruise Control model # purchased off E-Bay and the cruise now works properly. So it appears that the issue was a failed control board.

Please EDIT the title line, add "solved". Thanks.

 

[Tahoe97]

Please EDIT the title line, add "solved". Thanks.

Not sure how to get to the original title line.

 

[Fless]

Go to the top of the page, and above the first post there should be a 3-dot menu with a dropdown arrow. Click on that arrow and select "Edit thread" and change the text. Save.

Since I'm a moderator your menu might be slightly different, but since you are the OP you should be able to edit it.

 

[Tahoe97]

Go to the top of the page, and above the first post there should be a 3-dot menu with a dropdown arrow. Click on that arrow and select "Edit thread" and change the text. Save.

View attachment 439053

Since I'm a moderator your menu might be slightly different, but since you are the OP you should be able to edit it.

Can't find that option

 

[OR VietVet]

Can't find that option

Not there on your first post on July 21, post #1?