problem getting DBW cruise to work

[68basket]

I have read through the cruise thread and have the wiring from PSI.

It originally did not have wires in pins 4 5 and 14 at the tac module but psi sent them to me.

I checked pin 6 and it was getting power whenever the brake was not pushed and 0v when pedal was pushed this seemed backwards so i changed the main wire from the psi harness to the white wire at the original brake light switch. I now have 12v when brake is pressed and 0v when not pressed at pin 6 on TAc.

I am just using momentary pushbuttons to get cruise to work. i wired this so that with key on i have 12v at pin 14 on tac, then when i press my coast/activate pushbutton i do get 12v at pin 4 but the cruise will not set.

Unsure what i am doing wrong, i do have standard brake light bulbs.
ANy help would be very appreciated as i am driving this truck to atlanta on friday and cruise would be very nice to have!!

[ls1nova71]

Are you using the brake switch with the two sets of contacts? So that C1-33 on the PCM connector is getting 12v without the pedal depressed?

[68basket]

i am using a brake switch with 2 sets of contacts. From the psi harness there is a purple wire noted tcc and yes it gets 12v without the pedal depressed. i am unsure what pin on the pcm this wire goes to.

[ls1nova71]

Ok, that's correct. How is your brake light switch adjusted? So that the brake lights come on with very little movement of the pedal? If so, try adjusting it in a little more so that it takes a little more travel of the pedal before they come on. Not so much that the brakes are actually applying though.

Also, just to be sure, you are driving this when you're testing it correct? I had a guy try in vain to get his to work once, and then found out he had the car on jackstands in his garage.

[68basket]

i was thinking along the same lines with the brake switch adjustment, i did adjust it some so that the pedal has to be pressed an inch or 2 before the brake lights come on.

and yes i am doing 40-60mph trying to activate.

i know i am missing something simple and just need to find what it is.

I have been emailing jon at psi and while nice he has not been much help, suggesting that i need to wire an actual cruise switch instead of wiring 12v from key on to pin 14 and using momentary buttons to apply 12v to pin 4 to acivate. I see no reason my setup is not working.

[ls1nova71]

It probably is something simple, it usually turns out that way. It appears you have everything wired up correctly, so that shouldn't be it. Do you know if the truck your PCM came out of originally had cruise? I'm not a tuner, but I have a buddy who is, and I recall him saying something once about the cruise being enabled in the tune. Do you have any kind of scanner that shows live data?

[68basket]

i am unsure if the original truck had cruise,

i do have a couple of scanners at work that will show live data. We just got a snapon modis. WIll i be able to see cruise activation and such in there?

[ls1nova71]

Not sure with a MODIS, but a TechII would. You should probably be able to see brake switch on/off, and if the cruise is on or off. I would check into it and see what it's showing. Might be something obvious.

[68basket]

i will play around with it tomorrow at work and see if i can get it figured out. thanks for your help!!

[68basket]

just to update, i fixed it!!

hooked up the modis and looked in the TAC module. it saw cruise on, then it saw the activation button pressed, but it said the stop lamp was always activated. Well i found i had knocked the harness loose next to the gas pedal that goes to the harness for all the rear lights. plugged it and and now the values show the stop lamp switch not activated. Now cruise works!!

[ls1nova71]

Glad to hear you got it going. I figured a scanner would show something fairly obvious, and a lot of the time it's in the brake switch and/or it's adjustment. Have a safe trip to Atlanta and enjoy the drive.