Thanks for asking the question and joining the site.
If the light comes on then that generally means the entire system from the switch all the way down to the module and then up to the cluster is working. This means the issue is in the actually operational side of the system.
So there is either something telling the cruise to not engage or the control module is trying to engage the system and it is not able to do it.
If you have the same vehicle above you should have electronic throttle control. This means you don't have an actual cable that is attached from the pedal to the throttle body.
If that is the case then I bet you have an issue with the stop lamp switch or speed sensor.
However, if you have no issue with the speedometer then we can assume the speed sensor is okay.
That leaves the stop lamp switch. We can check this by monitoring it with a scan tool to see if there is any input at all on the switch. If there is it will deactivate the cruise but may not be enough input to turn the brake lights on. So basically it just turns the system off but leaves the light on so that you can re-engage it if you want to. However, it never lets you because it thinks the brakes are still applied.
If this is not it then we are turning to the PCM, cruise module, or the throttle body itself.
However, before we do anything we need to check for codes. If you have any codes for the PCM or ABS it will prevent the system from engaging.
https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing
Due to the fact that it engages sometimes, I am putting my money on the switch.
Please run through this and let me know what questions you have on this. Thanks
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Wednesday, September 8th, 2021 AT 11:41 AM
