97 LSC Cruise Control

[SteveB]

My cruise control stopped cooperating, so I got a used multi switch that is supposed to be good, put it in, and still don't have cruise control. All other functions on the column work. Is there any other relay or something that would control the cruise control that I should check before I try another clock spring?

Thanks!

SteveB
97 Black on Black LSC

 

[Neil]

Multi switch? Do you mean the cruise control steering wheel buttons?

Did you get the cruise control recall work done? If so is the fuse that was installed at the brake pressure switch still good? Do the brake lights work properly?

Are I/P fuses 32 and 34 good?

 

[SteveB]

Multi switch? Do you mean the cruise control steering wheel buttons?

Did you get the cruise control recall work done? If so is the fuse that was installed at the brake pressure switch still good? Do the brake lights work properly?

Are I/P fuses 32 and 34 good?

No, I think the buttons are fine. I put in a new/used clock spring, turn signal indicator, the whole thing behind the wheel. I did not have any cruise recall work done, and the last time I checked all the fuses, they were good.

 

[Neil]

The recall work involved installing a fuse in the circuit feeding the Deactivation Switch located at the front RH frame rail to the rear of the air suspension compressor.

It could leak brake fluid, short out and start a fire.

It is a normally closed switch that opens with brake fluid pressure and deactivates the cruise control. If it is faulty and open you won't be able to set the speed control.
It would be worth testing that switch.

Your trouble could be any of the following...

Deactivator Switch

Speed Control Actuator Switch

Vehicle Speed Sensor

Brake Pedal Position (BPP) Switch

Speed Control Servo

Here is a self test procedure...

WARNING: THIS TEST IS A KEY ON ENGINE OFF (KOEO) TEST ONLY THAT IS CONDUCTED IN PARK ONLY WITH EMERGENCY BRAKE FULLY ENGAGED.

Enter Self-Test Diagnostics by depressing the speed control OFF switch while turning the ignition key ON, ensuring engine does not start and is not running. The speed control indicator lamp on the instrument panel will flash once to indicate that the speed control module entered the diagnostic mode. Five additional flashes at this point indicate a defective speed control servo. Release the OFF switch.
NOTE: If the ON switch is not pressed within 5 seconds after entering the diagnostic mode, the module times out and the procedure must be started over.

Press the remaining switches in this sequence: ON, RESUME (RSM), COAST (CST), and SET/ACCEL.
The speed control indicator lamp will flash as each switch is pressed. Press each switch in the sequence immediately after the light goes out for the previous switch.
After all five speed control switches have been pressed, the indicator lamp will flash to indicate a Pass or Fail:
1 Flash - (With dynamic throttle pull).
2 Flashes - BPP switch defective, circuit defective, or brake pedal applied.
3 Flashes - Deactivator switch is open or circuit defective.
4 Flashes - Vehicle speed signal is out of range or not connected.
Immediately after the passed STATIC test, the speed control module then performs a DYNAMIC test automatically by actuating the throttle lever from 1mm to 10 mm of travel from the idle position. During the DYNAMIC throttle pull, observe the throttle movement to witness any binding or sticking of the actuator cable, proper connection of the actuator cable to the throttle lever, and ensure the THROTTLE RETURNS BACK TO IDLE POSITION.
Return ignition switch to the OFF position and proceed to the following Symptom Chart, if necessary.

Good luck

Neil

 

[SteveB]

Well, thank you very much, Neil! That's an impressive bit of knowledge you have there! I'm looking forward to trying your test. Thanks again!