1999 fld 120 cruise control not working?

Discussion in 'Freightliner Forum' started by 1985mudflap, Oct 5, 2021.

  1. 1985mudflap

    1985mudflap Bobtail Member

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    I can't get the cruise to working going down the road. I can idle the truck when the parking bakes are set. I have Jake's they cut out when the clutch is in gaged so I'm guessing it's not the clutch switch. I don't have a switch on my brake pedal. My speedo and tach also work. So I thought I would try the air switch, but I do not know which air switch is for the cruise control. I've found the air manifold behind the steer column just don't know which to change.
     
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  3. Old Man

    Old Man Road Train Member

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  4. 1985mudflap

    1985mudflap Bobtail Member

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    12.7 60 series detroit
     
  5. Old Man

    Old Man Road Train Member

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    Could be plug into ecm. The big one facing the fire wall, remove, clean and make sure it is in tight.
     
    1985mudflap Thanks this.
  6. 1985mudflap

    1985mudflap Bobtail Member

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    Thanks I'll look into that. Would you happen to have any info on air switches?
     
  7. Old Man

    Old Man Road Train Member

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  8. Rideandrepair

    Rideandrepair Road Train Member

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    I had same problem, till I found a second speed sensor on trans tail shaft. One on top, controls cruise. Bottom one controls speedo. Changed top one. Fixed. I don’t know if any air switches for cruise. One low air switch, and one brake light switch, usually plumbed in near parking brake, on FLD. Some Centuries and ? have them near steering column on right side.
     
  9. 1985mudflap

    1985mudflap Bobtail Member

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    I have one speed sensor on top of the transmission it have two plugs one for the road speed and I thought the other was for the cruise but I'll double check it. Thanks.
     
    Rideandrepair Thanks this.
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