Cruise control will not turn on - 2005 Kia Optima

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 .

Cruise Control Inoperative
Did you perform the Cruise Control System Check?
--
Go to Step 2
Go to Cruise Control System Check

2

1. Disconnect the cruise control module connector.
2. Turn the ignition switch to the RUN position.
3. Measure the voltage between terminal F of the cruise control module harness connector and ground.

Does the voltage equal the specified value?
B+
Go to Step 3 yes
Go to Step 4 no

3

Measure the voltage between terminal E and terminal F of the cruise control module harness connector.
Does the voltage equal the specified value?
B+
Go to Step 5
Go to Step 6

4

Repair the open in CKT 339 between the fuse block and the cruise control module. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
--
Go to Cruise Control System Check
--

5

1. Turn the cruise switch to the ON position.
2. Measure the voltage between terminal A of the cruise control module harness and ground.

Does the voltage equal the specified value?
B+
Go to Step 7 yes
Go to Step 8 no

check switch

Once you have turned your cruise control on accelerate to desired speed press SET button on right hand side of steering wheel before lifting foot from accelerator, then remove foot from accelerator. pushing RESUME button will deactivate cruise control without turning it off. Then when clear of traffic push resume again to activate cruise control. It will automatically resume to previous set speed.

by cruise control being PCM control have dealership code scan see what causing cruise control turn itself on.

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.

I had a similar problem and it turned out to be the brake fluid level. This may be an answer. Also have you had the brakes checked. The cruise control is integrated with the brakes. Any little thing wrong with them effects the cruise.

You have a short somewhere dude

look in your owner's manual for the location of the cruse control fuse it is different from other fuses usually much larger