Cruise control not working, when turning ignition

step 1
Remove the left sound insulator
step 2
the stop switch is here, way way up top
use flash light to see it.
it is there.
top of pedal it is there. SM books step1.

buy the service manual.?
if the switch ever sticks on , cruise ENDS
it is a NO, switch normally open contarts
no calibration is stated so its PnP

Do you know how it works ? What controls it ?

Did you hook up a scan tool an check for DTC'S - diagnostic trouble codes ?

Cruise Control Description and Operation
Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions. However, steep grades may cause variations in the selected speeds. The electronic cruise control system has the capability to CRUISE, COAST, RESUME SPEED, ACCELERATE, TAP-UP or TAP-DOWN.
The main parts of the cruise control system are:
• The powertrain control module (PCM)
• The function control switches
• The stop lamp switch assembly
The cruise control system uses the powertrain control module (PCM) to maintain the desired vehicle cruise speed . The PCM assembly contains a low speed limit which will prevent system engagement below a minimum speed of 40 km/h (25 mph). The PCM assembly is not serviceable.
Cruise control operation is controlled through the function control switches located on the multifunction turn signal lever. The cruise control function control switches includes the ON/OFF, SET/COAST, R/A (resume/accelerate). The switch assembly provides driver control of the cruise control system.
The stop lamp switch is used to disengage the cruise control. A cruise control release switch circuit and a stop lamp switch circuit are used. The stop lamp switch is mounted to the brake pedal bracket . To disengage the system the driver presses the brake pedal. The speed of the vehicle at brake actuation will be stored in the memory of the PCM.
With cruise control, the vehicle can maintain a speed of about 40 km/h (25 mph) or more without keeping your foot on the accelerator. When the driver turns off the cruise control ON/OFF switch or ignition switch, the cruise control turns off. The vehicle speed stored in the memory of the PCM will be lost.
Ignition positive voltage is supplied from the HVAC fuse, to the cruise control switch. When the cruise control ON/OFF switch is on, ignition positive voltage is applied to the cruise on switch signal circuit terminal of the PCM. If the driver has not pressed the brake pedal, ignition positive voltage is supplied through the stop lamp switch, TCC/Brake signal contacts to the cruise control brake pedal switch signal circuit terminals of the PCM. Cruise control is canceled when the driver presses the brake pedal. The stop lamp switch contacts close, applying battery positive voltage to the stop lamp signal circuit of the PCM. At the same time, the TCC/Brake contacts of the stop lamp switch open and voltage is removed from the brake pedal signal circuit at the PCM. When pressing the SET/COAST button on the multifunction turn signal lever, ignition positive voltage is applied to the set/coast switch signal terminal of the PCM. When pressing the R/A (resume/accelerate) on the control switch, ignition positive voltage is applied to the resume/accelerate switch signal terminal of the PCM.
When the cruise switch is in the ON position, and the driver presses the SET/COAST button, the PCM then checks to see that the cruise control enable criteria is met. If the cruise control criteria has been met the PCM sends a class 2 message to the instrument panel cluster (IPC) to illuminate the cruise light.
The PCM will inhibit cruise control:
• When the PCM detects that the center high mounted stop lamp (CHMSL) in not operating properly.
• When vehicle speed is less than 40 km/h (25 mph).
• When in PARK, REVERSE, NEUTRAL, or 1st gear.
• With low engine RPM
• With high engine RPM (fuel cut-off)
• When vehicle speed is to high
• When an over or under charged battery voltage condition exists
• Antilock brake system/traction control system is active for more than 2 seconds
If the PCM determines that any of the cruise control inhibit conditions are present, the PCM will disengage the cruise control. If the PCM disables the cruise control for an inhibiting event it will record the reason for disengagement in the Disengage Definition data file.

Do you know how to test electrical circuits with a DVOM - digital volt ohmmeter, looking at a wiring diagram for the CC so you know what wires to test , if not your best bet might be to take it to a qualified repair shop .

The cruise control system on this vehicle uses mechanical, electrical and vacuum operated components to maintain vehicle speeds over 25 MPH. The cruise control unit receives command signals from the cruise control main switch and the set/resume switch. It also receives operating signals form the brake light switch, ignition coil, speed sensor, clutch switch (manual transmission) or shift position switch (automatic transmission). If the main switch's indicator light illuminates when turned on, it's likely working properly. Likewise, if the cruise control light on the instrument cluster illuminates when the set/resume switch is pressed, it is likely OK. At this point the problem would likely be mechanical or vacuum-related rather than electrical and the actuator/servo would be the prime suspect. On the other hand if the cluster indicator light is not illuminating, it could be an electrical issue such as the set switch not registering or one of the safety switches (brake switch, clutch switch or shift position switch) registering inappropriately which effectively cancels the cruise request. You can read more here: https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-cruise-control-switch

Which engine ?
Cruise Control Description and Operation (3.6L)
Cruise Control Description and Operation (3.4L)

Do you know what all is involved in C.C. operation ?


Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions at speeds above 40km/h (25 mph). However, steep grades may cause variations in the selected speeds. The main components of the cruise control system are:
• The cruise control module assembly
• The cruise control switches
• The cruise control release switch
• The powertrain control module (PCM)
• The stoplamp switch assembly
• The vehicle speed sensor


The cruise control module controls the operation of the cruise control system. The cruise control module monitors the signal circuits of the cruise control switches. When the normally open cruise On/Off switch closes with a switch activation, the cruise control modules detects a high voltage on the signal circuit. The cruise control module activates the cruise control system.The set/coast switch and the resume/accel switch will not operate the system when the cruise control module has not activated the system based on the cruise control on/off switch signal circuit .
The cruise control module monitors the cruise control set/coast switch in order to determine when to capture and maintain the vehicle speed. The cruise control module monitors the vehicle speed signal circuit in order to determine the desired speed. The PCM pulses the vehicle speed signal circuit at 4000 pulses per minute. After an initial set speed has been established, the cruise control module also uses the cruise control set/coast switch signal circuit in order to tap down the set speed when the cruise control module detects a switch activation.
The cruise control module monitors the cruise control resume/accel switch signal circuit in order to determine when to resume the previous set speed. This feature only works within the same ignition cycle and as long as the cruise wasn't turned off using the cruise control On/Off switch since the last cruise engagement. After the set speed has been resumed, the cruise control module also uses the cruise control resume/accel switch signal circuit in order to tap up the set speed when the cruise control module detects a switch activation.
The cruise control module assembly has a controller and an electric stepper motor to vary the throttle in each different cruise control mode. Two components in the module assembly help to do this. The electronic controller and the electric stepper motor. The controller monitors vehicle speed and operates the stepper motor. The stepper motor operates in response to the controller, to maintain the desired cruise speed. The electric stepper motor moves a strap that is attached to the cruise control cable which moves the throttle

Which engine does your trailblazer have 5.3 or 4.2 L
Cruise Control Description and Operation (5.3L)
Cruise Control Description and Operation (4.2L)
makes a difference ! The best way to start diagnostic's is with a scan tool . May have DTC'S diagnostic trouble codes .
DTC P1574 Stop Lamp Switch Circuit
DTC P0568 Cruise Control Set Switch Circuit
DTC P0567 Cruise Control Resume Switch Circuit
Plus with a scan tool you can see if the cruise control switch is inputing to PCM. Data list .
The cruise control resume/accel switch is an input to the powertrain control module (PCM). The PCM uses the cruise control resume/accel switch signal circuit in order to detect when the driver has requested to accelerate the set vehicle speed or to resume the cruise control system. The PCM detects a voltage signal on the cruise control resume/accel switch signal circuit when the switch is applied. This DTC sets if the PCM senses voltage on the cruise control resume/accel switch signal circuit for longer than 90 seconds.
Cruise Control Indicator Inoperative (4.2L)
Turn OFF the ignition.
Install a scan tool.
Turn ON the ignition, with the engine OFF.
With the scan tool, Command the Cruise Control Lamp Test parameter ON, in the instrument panel cluster (IPC) Output Controls.
Does the Cruise indicator illuminate in the IPC?
YES - Go to Step 3
no - Go to Step 4
3
Inspect for poor connections at the harness connector of the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?
YES - Go to Step 7
NO - Go to Step 6
4
Inspect for poor connections at the harness connector of the IPC. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?
YES - Go to Step 7
NO - Go to Step 5
5
Replace the IPC. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?
YES - Go to Step 7
--
6
Replace the PCM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?
Go to Step 7
--
7
Operate the system in order to verify the repair.
Does the system operate properly?
System OK
Go to Step 2

Cruise Control Inoperative/Malfunctioning (4.2L)

Install a scan tool.
Turn ON the ignition, with the engine OFF.
Press the cruise ON/OFF switch OFF.
With the scan tool, observe the Cruise ON/OFF switch parameter in the powertrain control module (PCM) Cruise Control Data list.
Does the Cruise ON/OFF switch parameter display OFF?

Your best bet mite be to take your vehicle to the dealer .

If cruise control main light comes on but you cannot set a speed (no set), you could have a bad brake pedal switch.
(If the cruise control light comes on, chances are that it is NOT a fuse issue).
Some vehicles have two switches (one for brake lights and one for cruise control cancel) and others have a multifunctional, single switch.
The function to cancel cruise control is very sensitive so it only takes a small movement of the pedal to cancel cruise control.
You can try lifting on the brake pedal while trying to set the cruise, but this does not alway work. Replace switches are pretty cheap (less than $30) and pretty easy and quick to replace.

I would check the turn signal switch. The cruise and turn signal are on the same switch. The brake lights go through the switch before going to the brake lights. And the turn signals don't work with the ignition off.

Hi, there are two brake switches on this system, one is for a Brake Light circuit while the other powers up the Cruise Control and Brake Transmission Shift Interlock Solenoid. This switch is a normally closed switch that opens when the pedal is depressed. Power from this switch is feed to the PCM which then powers up the Cruise Control Servo. The contacts of this brake switch can make poor contact which reduces the current flow to the Cruise Control Servo. To test for this problem, find the brake switch with the Gray wire and Brown wire. Back probe and jumper the Gray wire to the Brown wire. Test drive the vehicle. If the cruise control now works, replace the Cruise/Shift/Interlock Brake Switch. The brake switch is located behind the brake pedal.

possible bad speed sensor, get computer codes

I had a problem with the interlock switch located on the brake pedal. There are too switches one for the brake lights and one dedicated to the cruise control. If either switch is acting up it will affect the cruise control. Then interlock switch is the same switch that is used on the clutch with cars that have a manual transmission. It has smaller electrical terminals in the connector than the brake light switch. You can jumper the connection and see if it solves the problem. You still have the other switch that will disengage the cruise control when you hit the brake. If that is the problem then that's the one you need to replace.