Envoy 2005 XL Cruise control not working

You do not have a cruze module like the old days. The throttle body is an electric motor and is controlled by the ECU

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

Here is the fuse box diagrams for the 2 different engine options...and the 2 different box locations
Buick Rainer 2003 2006 fuse box diagram Auto Genius
HOWEVER ... I do not think there is an associated fuse for cruise control. That function is totally run from your on board computer (ECM). What can make the cruise not work is if any fault codes have occurred... Has your check engine light come on?
Some people with the same problem (that do not have an OBDll scanner to read or clear codes) disconnected their battery to reset the ECM. The cruise control then worked .... but if the root cause of the fault is not fixed ... then the same thing will likely happen again
Helpful?
Good luck with your troubleshooting

Cruise Control on your vehicle is computer controlled , having the vehicle checked for DTC'S - diagnostic trouble codes should be the first step in diagnosing this problem . Not a code reader or autozone etc... Would need a factory Tech 2 scanner or someother professional type , one that can read BCM - body control module codes .
Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions at speeds above 40 km/h (25 mph). Steep grades may cause variations in the selected vehicle speeds.
The following are the main components of the Cruise Control System:
• The accelerator pedal
• The brake pedal position (BPP) sensor
• The body control module (BCM)
• The cruise control on/off switch
• The powertrain control module (PCM)
• The + RES switch
The + RES switch is the equivalent to an accel/resume switch.
• The - SET switch
The - SET switch is the equivalent to a set/coast switch.
• The throttle actuator control (TAC) module
• The TAC motor
• The vehicle speed sensor (VSS)

Check the linkage at the advance to se if it is broken. Some are by mechanical connection and others are by vacuum. If vacuum you have developed a leak and must replace the controler to make it work again.

Could be a bad instrument cluster (bad stepper motor) or the vehicle speed sensor is bad. Does cruise control work, if it does then it is the cluster.

Going up hill's an loses power , plugged catalytic converter . No relay for the cruise control . Your best bet , take your vehicle to a qualified repair shop.

Why not save a lot of money and aggravation,
and just go down the street to a local repair shop?

2002 ENVOY BRAKE LIGHTS WONT WORK

I would guess it is the electronic fan clutch. It will cause the fan to run too fast (very loud) and the light will come on sometimes.