Yep, turn signals

according to GM only 3 actions will terminate the cruise control function, (the power does pass through the inflatable restraint system so I'm guessing an impact will shut it down also)
brake switch,
cruise control on/off switch,
cruise control cancel switch

If you have access to a scanner that can see the stored data you can see what function terminated the cruise control function for the last 8 events

Neal,

 

Thanks Neal,
I Have the GM Version of the Tech 2 I havent use it in a long time. So I'll have to figure out how to get to that screen. Don't believe I have ever gone into looking for that kind of sequence of hunting. I am not Tech Two 100% savie. Any help in going thru the menu to get what I need to see would be helpful.

Thanks Again for your reply.

Mark R

 

The Stop Lamps are monitored by the EBCM which is possibly expecting to see an minimum resistance (current) to ground, that's why replacing them with straight LEDS can be problematic.

In the UK we use the term "Brake" rather than "Stop" in mitigation it's the "Electronic Brake Control Module"

past post

 

So a little more investigating leads to what GM calls "Cruise Control Inhibit" (controlled b the ECM) which looks to be a few items that will keep the cruise from engaging,

*ECM has not detected a brake pedal activation from the BCM
*A Cruise Control System DTC has been set
*Speed is less than 25 mph
*speed is to high ????
*truck is in Park, Neutral, Reverse or 1st gear
*engine RPM to low
*engine RPM to high
*system voltage not between 9-16 volts
*ABS or TCS active for more than 2 seconds

looking through the data the EBCM does not look to be part of the Cruise Control system

Neal

 

I'll take a look at mine to track down the process for the tech2 to look at the history

Neal

 

@legerwn
TBH not 100% on this, below highlighted in yellow is a possible clue, perhaps the "STOP LAMP SUPPLY VOLTAGE" is actually monitored by the EBCM which communicates to the BCM?




The simplified equivalent circuit below is pure guess work, but possibly how the stop lamp current is measured by the EBCM
Imagine the RESISTOR is 0.1 ohms then at 4.5A V1 would be approx 0.5V.

If only one STOP lamp is fitted would the cruise control still work?
(probably does as a 6 ohm resistor works)

 

Thanks Neal for the hard work doing that schematic. I notice all terminates at the rear ground point. Also:

I can rule out all except *system voltage not between 9-16 volts+* And as far as "*ABS or TCS active for more than 2 seconds* not seeing any ABS TCS warnings popping up and going away. I think your suggestion about looking at the last events which turned off the Cruise Control is viable. Except as stated I would need guidance in regards to step by step to page to the right place on the GM Tech 2.

What do you think about the rear Junction block at point "G401" An intermittent Ground causing a Slight voltage Fluctuation enough to trigger the cruise off. I would think it doesn't take much of a Voltage swing say .05 to 1 Volt to tell crusie to disengage or not set. Like I said..i can go out now with a cold 2 and the crusie will work maybe once or twice and then not work at all. It seems when the 2 is cold it works. Then sometimes it will continue to work when hot.

Sound like a Tech 2 Hunt???

Thanks again to all for helping..

​​​​​​​Mark R

 

K,
the tech2 steps are;
build truck, 2009 Hummer h2
then as follows,
1) Powertrain
2) Select engine if there are options, mine goes to L92
3) ECM
4) Cruise/PTO/Traction
5) Live data
within this data stream will be cruise history 1-8 showing the last 8 cruise terminations, my truck had 26 data points and the cruise data was at the end of the stream so I had to page down to get to it.

Neal

 

oceanbrave,
I don't know how the truck knows when a LED is installed other then a change in voltage are amperage when the brake is applied
these trucks have an amperage sensor at the battery but don't know if it uses this sensor other then to charge the battery, it is an integral part of the charging system.

You are more proficient with the electrical systems then me for sure

I'm working through a similar issue with my sons 99 silverado, we installed an LED 3rd brake light and it defeated the cruise control, validated by removing the LED and installing the OEM brake light and the cruise works. still working to understand this one.

Neal

 

Mark,
On my list of cruise history I had 3 things that shut the cruise down
Brake pedal
Pedal Initialization (pressing the throttle while the cruise is on)
Steering wheel switch to shut it off

Neal