Detroit 60 cruise control

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Trugo, Mar 10, 2019.

  1. Trugo

    Trugo Light Load Member

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    im trying to get the cruise control working. It’s a Detroit ddec 3 engine in a 1995 freightliner fld. The high idle works with the parking brake on.

    When driving cruise does not work. I checked the clutch switch, it was broken so I looped the wires but still no cruise.

    Then I noticed the brake lights are not working. Hmm maybe these problems are related.

    I looked behind the brake pedal at the air manifold. It has 4 air switches. One of them is working with the brake pedal engaged, putting out a positive signal.

    I could the rewire the brake lights off that. But I don’t know what to do for the cruise. Rewire to ecm? I do have the ddec pin out but I don’t know if it would get positive or ground.

    Does anyone know if there’s a stop light relay? Half my relay labels are unreadable. This could be a relay problem. I’m thinking about starting by redoing the cab ground cable.

    Advice appreciated.
     
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  3. benjamin260_6

    benjamin260_6 Medium Load Member

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    Ontario, Canada
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    You have to ground the pins from the ecm to activate
     
  4. Rideandrepair

    Rideandrepair Road Train Member

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    You may have a second speed sensor on top of trans. If so change it out
     
  5. McMahons Trucking

    McMahons Trucking Light Load Member

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    I have a 94 Pete and it has a sensor under the dash taht senses air pressure before the cruise will work.
     
  6. Trugo

    Trugo Light Load Member

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    ok I’ll have to check at the ecm connector that both the brake and clutch pedal switches are sending grounds. If I understand correctly.

    haven’t checked that yet. On the to do list...

    got some air switches. One may be for brake pedal switch which is Separate from the brake light switch. Haven’t verified that, yet.
     
  7. Trugo

    Trugo Light Load Member

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    Fixed the brake light problem, seems unrelated. Still no cruise.
     
  8. jameslawton

    jameslawton Light Load Member

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    i would check the park brake switch if works when park brake set but dont work going down road i would start with park brake switch and speed sensors
     
  9. Trugo

    Trugo Light Load Member

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    Dec 8, 2015
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    Yes the park brake switch works. High idle works. But not going down road. I’m going to check this morning that the ecm is receiving ground for clutch & brake pedal switches. If ok I’ll move onto the speed sensor. The speedometer is working.
     
  10. Rideandrepair

    Rideandrepair Road Train Member

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    My speedo was working also, I had already replaced sensor, fixed speedo, but cruise still didn’t work. After quite a while, I learned of 2nd sensor.odometer still doesn’t worked though.Srange, after I responded to this thread, my cruise is intermittent. I think it’s just my set/coast switch. I keep xtras as they’re always breaking.
     
    Trugo Thanks this.
  11. Trugo

    Trugo Light Load Member

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    Dec 8, 2015
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    I looked at the speed sensor. This Eaton 10 speed has only one sensor. It’s a 4 wire speed sensor which branches off into 2 plugs.

    But I didn’t need to look into that. I checked the ecm connector, which was getting a ground from the clutch switch but not from the service brake switch. These are pins j2 and g2. So I jumped the brake switch wires behind the steering column on the air switch manifold. This gave me a ground at both j2 and g2. Testing, cruise works as expected. It’s fair to say my brake switch is bad.

    I think I might hook up the brake switch wire to the brake lights which run off a separate switch using a relay.

    For now, problem solved. Thanks for help.
     
    Rideandrepair Thanks this.
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