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Hey guys. First a little backstory. Truck was auto, put in the nv5600 2 years ago. Bob Wagner sent me a smarty flash to change up the ECU. Cruise worked awesome after for many months. After that the light would come on the dash and it would be working than the light on the dash would turn off and cruise would kick out, almost like the brake was pushed.

It kept doing this for months, sometimes it would take pressing the cruise on button 20 times before the words showed up on the dash, but once the words showed up it worked awesome until it cuts out. I am assuming maybe electrical because when the dash light works it works and vice versa. It has got to the point where cruise never works.

After doing some reading i found that the vacuum lines are known to leak. I tested with a vacuum pump and everything held vacuum so no leak. I found what i think is the vacuum pump on the passenger fender well in front of where the PCM is on an auto. The pump is not plugged in. I searched both wiring harnesses (current and the old one) for the matching plug and found nothing. I find it odd that the cruise intermittently worked and that the,pump us unplugged? I found another 03 auto and his pump is plugged into this conector that i do not have visible. As far as i know the plug comes from the across firewall harness but cannot find this plug anywhere.

Open to all suggestions and advice. Thanks
 

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yes thats your vac pump. And yes the plug comes out of the wire loom directly above the pump as it runs across the firewall. Check for it tucked up inside that wire loom? otherwise I have no clue why yours is missin unless someone cut it off for some reason? Are you the only owner of the vehicle?

I can tell you that my pump isnt working or I have a leak because I too can engage it and it will hold for several seconds and then cut off. Been like that for years but I never use cruise so never bothered to trace down the problem. SO it may be engaged initially by the ECM then vac pump takes over, I dont know. But thats prob why yours works initially then cuts off. because its unplugged
 

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Mr. Vehicle Destroyer
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sounds like your switch or clock spring are NFG. if it worked after the swap, then something either wore out or came unplugged.
 
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