Clutch switch input for cruise control

[Skonnie Speed Shop]

I have a gen 3 LS with a manual trans. Its DBW LQ9. I am trying to get the cruise control working. I see the "cruise on" and "set/coast" inputs change correctly in the log. I have confirmed 12v to pin 33 of the blue connector of the ECM that goes to 0v when the brake pedal is pressed. I also have 12v to pin 6 of the TAC module when then brakes are pressed and 0v when the pedal is released. This is through a changeover relay that grounds the line when the brake pedal is not pressed. I have read a lot about the issues with the brake inputs to the ECM and TAC module. I have not found any info on vehicle with manual transmissions. I am assuming the "torque converter clutch off" signal does not need to be seen when the vehicle has a manual transmission and is replaced by the clutch position switch signal. From what I can tell they are the same signal (12v present, 0V when pedal is pressed). I connected that signal to the blue connector pin 33 and tested and I cannot get the cruise control lockout to read "no". I have tried it multiple times over 45 mph.

Any help you can provide will be greatly appreciated.

Thank You

[Skonnie Speed Shop]

I have also confirmed both the brake switch inputs to the PCM and the TAC using a scanner. Both inputs are recognized simultaneously.

[relicdew]

BlueGreen_Cruise_DBW_Schematic.pdf

See attached cruise schematic. Position 35 on the Blue PCM connector is your clutch switch input.

It looks like you'll need to provide the clutch wire +12V for it to say released. When you push the clutch position 35 will see 0V and go to apply status.

[Skonnie Speed Shop]

Thank you for the response. I have connected pin 35 on the blue PCM connector to the switch the sends 12V when the pedal is released and 0V when the pedal is pressed. The cruise lockout will not release.

The PCM is from an automatic vehicle. Is there something that needs to be done in the tune? The PRNDL is set to none and the transmission is set to manual.

I might try setting the transmission to the "non electrical automatic" setting and connecting the pedal switch to the TCC signal of the PCM (pin 35)

Thank You

[relicdew]

If you're OS and tune is from an automatic, that's the issue. You must start with a proper manual tune in the PCM before these functions will exist. In my experience, these drop downs on some things don't have any affect on anything.

[Skonnie Speed Shop]

Thank you. Can I segment swap just the transmission and transmission diag from manual vehicle with the same OS as mine? Or do I need to swap the engine stuff too?

Thank You

[Alvin]

Thank you. Can I segment swap just the transmission and transmission diag from manual vehicle with the same OS as mine? Or do I need to swap the engine stuff too?

Thank You

No one will know that until they or you try it.

Personally I'd start with a manual file.


I did do what you are doing now. It was a 87 C10 with a T56. FBW. I used a manual vette file as a base. I got many of the ideas from Mike Noonans EFI LS swap book. This was 15 years ago at this point.