Does brake light switch affect cruise control?

Take your Rainier out for a drive and see if the cruise control still works. If it does, the VSS is likely fine. If not, the VSS could be the culprit (Vehicle Speed Sensor). Cruise control also depends on throttle position. Ensure that the throttle body and related components are functioning properly. Examine the wiring going to and from the VSS. Look for any damaged or frayed wires.

The most common reasons for cruise control malfunction are failed control modules, faulty sensors, or switch issues. While you've already replaced the brake switch module, it's essential to verify that it's functioning correctly.

Additionally, check other control modules related to the cruise control system. While you've already replaced the brake switch module, there might be a separate cruise control module. Inspect this module for any signs of malfunction.

Powertrain Control Module (PCM): The PCM monitors the signal circuits of the cruise control switches to determine when to capture and maintain the selected vehicle speed. It uses the throttle actuator control (TAC) module motor to control the vehicle speed. That would be something to check. Visually check cable connections and for corrosion. A multimeter can check the battery which can affect the PCM.

Sometimes, disconnecting the battery to clear any fault codes can resolve cruise control issues. Possibly that might work even though you see no fault codes.

There are several possible reasons why your cruise control may have stopped working. Here are some steps you can take to diagnose the issue:

1. Check the cruise control fuse: The first thing to check is the fuse that controls the cruise control system. Refer to your vehicle's owner manual to locate the fuse box and find the specific fuse for the cruise control. If the fuse is blown, replace it with a new one.
2. Check the brake light switch: The cruise control system is designed to disengage when you step on the brake pedal. If the brake light switch is faulty, the cruise control system may not work. You can test the switch by pressing the brake pedal and checking if the brake lights come on. If the brake lights don't come on, you may need to replace the brake light switch.
3. Check the speed sensor: The speed sensor is responsible for detecting the vehicle's speed and communicating it to the cruise control system. If the speed sensor is faulty or dirty, the cruise control system may not work. You can test the speed sensor with a multimeter or take your vehicle to a mechanic to have it tested.
4. Check the cruise control module: If all the above steps check out, the problem may be with the cruise control module itself. The module may be faulty and may need to be replaced. You can take your vehicle to a mechanic to have the module tested and replaced if necessary.

It's always recommended to consult with a certified mechanic or technician to diagnose and fix issues related to the cruise control system in your vehicle. They will have the expertise and necessary tools to troubleshoot the problem and provide the appropriate solution.

cruise control module has failed. or if your brake lights are staying on, then brake light switch has failed and not allowing cruise to engage. Have someone stand behind truck and see if brakes are working properly, if not- replace brake light switch. if fine, then swap out cruise control module under hood.... prob find one at a junk yard.

not being informed if it is auto or manual, here are some of the items that control the cruise control
brake pedal sensor ,
clutch pedal sensor,
vehicle speed sensor
engine ignition control module , tacho ,
vehicle speed --will disconnect if the road speed is below setting minimum speed
ratio changing
bad cruise control switch
wiring and connections
ecm problems
problem cruise control module

Sounds like you need to replace the brake light switch. This also affects cruise control and, of course, brake lights. They probably come on late and the cruise might not disengage without a bit of pedal pressure.

the following items either individually or together stops the cruise control from working ( you didn't mention auto or manual box)
VSS, ( auto or drive shaft sensor in manual)
brake light switch / sensor/
clutch position sensor ( manual)
fuse
cruise control switch
,fuse
wire to the ignition control module /tacho
cruise control module
ECM

The brake light switch, located on the brake padal assembly, is and input to the cruise control module. When the switch fails keeping the lights on is makes the cruise control module think you are applying the brakes when infact you are not. Chek the switch wiring for damage and if ok replace the switch making sure you adjust it properly.

Cruise control deactivates once you press the brake pedal. The brake switch us an input to the cruise control module. So it is possible that your brake switch went bad keping the lights on and making the cruise control module think you are applying the brakes when in fact you are not. Replace the brake light switch and check operation.

Cruise controls can cease to engage if the clutch or brake light cruise switch are out of adjustment. If this happens, try placing you foot under the clutch pedal (if equipped) and lift up on it (toward you) and hold it while engaging the cruise. If it now works, it will likely cut out when you remove your foot from under the pedal. Check the brake pedal in an identical fashion. Adjusting the switch at the pedals can often solve he problem. Some vehicles (Honda, Acura, Ford, to name a few) have a plastic insert that mounts in the pedal arm which presses against the switch. These can become brittle and fracture into pieces. My Acura has little pieces of blue plastic on the floorboard around the brake pedal one afternoon and I noticed the cruise didn't work. It was the pieces of the insert that had come to pieces preventing the cruise from coming on. I replaced the insert and no more problem with the cruise.

If both the RED brake light and the ABS light are coming on while you are driving the car, you either have an hydraulic failure or there is a problem with your ABS module that can potentially affect your regular service brakes.

The first thing to do would be to check the fluid level in your brake master cylinder. If it is low, you need to find out WHY. There is always a reason for the fluid level to be low. It is NOT SAFE to just add fluid without correcting the problem that caused the fluid level to be low.

If the fluid level is OK, then you must scan your antilock brake module for fault codes. The antilock brake module controls the antilock light and can affect the RED brake light as well. There are many different possible failures that can cause this. There is NO OTHER WAY to know why the antilock module has turned the light on. You can spin your wheels for days, replace a BUNCH of parts and never find the problem if you do not scan the module first.