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This is my cruise control using a GM control module #25169208 . GM trucks about 1995-2000.  I modified the original wiring diagram  to incorporate the Universal Speedometer Signal Interface (SGI-5) from Dakota Digital. I am using it to both correct my inaccurate speedometer and send a signal tothe cruise control.

Master wiring schematic.pdf cruise module plug wiring.pdf

Click on wiring images to get the full size PDF file

Dakota Digital Universal Speedometer Signal Interface

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Master wiring schematic

switch panel wiring.pdf under dash terminal block.pdf

Switch Panel Wiring

Under Dash Wiring

These diagrams are how I did my wiring using the switches in the picture that have their own built in light.

Pin out detail

Note on SGI-5: This is “Application #2” on the Dakota Digital instruction sheet. I used the speed signal from the speed sensor on the transmission. I originally used output #3 but cruise would not engage below 55 MPH, I changed to output #5 and it now works above about 30 MPH.

Brake light–already on vehicle

Cruise on–on/off

Cruise set–normally open momentary contact

Cruise resume–normally open momentary contact

Cruise set–normally open momentary contact

Brake pedal–normally closed

Clutch pedal if used–normally closed

Disengage–normally closed


I used a normally open switch held closed for my brake pedal switch. The switch marked “Coast” on  my control panel is a disengage switch. Brake,clutch and disengage are wired in series.

When cruise is engaged, “Set” button reduces set speed and “Resume” button increases speed.

 I got these plans from a friend, and various web sources. It is my understanding but, not verified, that other GM cruise modules will not work. Some have hacked and mounted the original GM turn signal lever, not all are wired with normally open switches and required relays to make them work. I like my dash mounted controls with the pretty lights.

My bus is rear engine which is why I attached the cable to the accelerator pedal. I was told the module isn’t strong enough to pull against the governor if mounted on the engine.

It has occurred to me that you could make a steering wheel mounted button control using a 4 relay RC module.

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