Cruise control will not turn on

When you are saying the cruise will not turn on, does the indicator in the dash come on when you turn the system on, and it will just not set on the speed selected? Or does the indicator not come on either?

This is going to cause the issue to be different, so we need to start with this.

The way I read the issue is the indicator comes on but it does not set the speed.

If this is the case, then this is most likely one of two issues. First and foremost, it is the brake switch or deactivation switch.

The brake pedal switch is on the brake pedal arm, and it tells the vehicle if you are pressing the brakes. Sometimes these stick on slightly and if it thinks you are pressing the brakes then it will not turn the cruise on.

You can test this by checking the voltage coming out of the switch. It should be an open circuit unless the brakes are pressed.

The same thing with the deactivation switch. When this fails, it thinks the system needs to be turned off and so it won't allow you to activate it. This can be tested by just unplugging the sensor and jumping the switch terminals in the connector to see if the cruise comes on.

The other common failure when the light comes on in the dash is the servo. Basically, it just doesn't engage the cruise.

Please see the info attached for this including the wiring diagram so we can start testing if needed.

https://www.2carpros.com/articles/how-to-check-wiring

Please see the attached below and let us know what you find with this.

Okay. That is great info. Normally this is a switch issue but if you replaced them and you can press these buttons and get the light to come on then that shows the buttons are working and at least getting power to the servo.

However, we need to just jump to the servo and check the power on the highlighted wires below. The complete wiring diagram is above but we need to check the voltage and make sure we are getting proper voltage on each one.

Test the switch circuits when you are pressing those buttons on the steering wheel. Then tell me what the voltage is on the other circuits, and we can go from there.

https://www.2carpros.com/articles/how-to-check-wiring

Thanks

I assume when you said ohms when pressing the resume, on/set, coast buttons, you meant you have 4, 6, and 7 volts? Basically, the way this works is when you press these buttons the voltage signal runs through different resistors that changes the voltage that actually makes it to the servo and based on this voltage it knows what button you are pressing.

If this is the case, then yes you have a servo issue. Just to be sure, I would check the last three wires.

Number 7 should have battery voltage which appears you do. I would just check this using pin 10 as your ground for your meter just to make sure the module has a good ground. Basically, checking the voltage on pin 7 to pin 10 you should have the same 12 volts.

Lastly check voltage at pin 9. If you are not pressing the brake, then you should have an open circuit. However, this is not going to prevent the light from coming on.

If the cruise is engaged and you hit the brakes, then the light should stay on, but it just disengages. So, I assume the brake input is fine, but it is nice to make sure.

Correct. I think the servo is the issue.

What happens is, you press the buttons, and the servo sees those button presses. Then the servo engages the throttle and holds it in place, and it turns the light on by grounding that circuit.

The fact that you have 10 volts on pin 1 shows it is not grounding the circuit. If the lamp was on, then you would have very little voltage at the servo because the bulb is using it to illuminate.

So basically, we know the servo is getting the commands from the buttons to turn on the cruise, but it is not doing anything. So everything going into the servo appears to be correct, but the servo is not doing anything.

This is one of the most common failures that causes this issue so if it were me, based on this info, I have seen enough to replace it.

Sounds good. Thanks for the update.

We will wait to hear back with some good news.

Okay. Just reading through this again. I just want to confirm exactly what is happening.

When you are driving the vehicle, you are trying to set the cruise and the light will not even come on? Or when you are sitting still trying to turn it on the light in the dash will not turn on?

Clearly a servo makes sense with all these voltage readings but that is highly unlikely that you got another that has the same issue.

Basically, when you are driving this vehicle above 40 MPH does the light come on and set the speed control?

There is a speed input so if we are not testing this at speed then let's start with that before we go much further.

Okay. I didn't notice this before because you said that the buttons all made the light come on when you did this test of turning the vehicle off while holding the off button.

However, you said that at the servo on pin 5 when you pressed the on button you had 5.7 volts. Is that correct?

If so, follow this testing through because what I see is you get to step E5 and the answer is no. Then you go to E6 where you are checking the circuit through the clock spring.

This would make sense because you have voltage so the test where the lights all respond "passes" because you are getting voltage. However, the servo is not going to turn this on because it needs to be over 10 volts. This appears to be what mislead us.

Run through this and make sure you are getting the same thing. Thanks