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Flying Finn

Engine brake

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We have a 2001 Volvo 770 with a Cummins ISX equipped with a 3 stage engine brake.  It doesn't always work when I flip the switch.  I have had the ECM programed so that the brake should work with or without the cruise control being turned on.  Sometimes it works going down hill or slowing for an exit ramp.  Never know until I try it.

Before I take in for repair was wondering what you guys think could be the problem.

Thanks

Brad

 

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Sometimes the brake or clutch engage/disengage switch(s) will get old.....or the pedals are not returning to the right position.  Try putting your foot under the clutch pedal and lift up to engage the switch and see if cruise will engage.  Try the same on the brake pedal. You may have to hold both pedals to engage the switches.  Some folks have used a small bungee cord to "lift up" on the pedal(s). 

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I actually implemented the "bungee" trick on my 2007 VNL670 brake pedal to keep the cruise-control on.  I know that there is a procedure for adjusting the brake pedal on the foot valve.  Below is what I found online,.  If anyone can verify this procedure, I would be thrilled to get rid of my bungee!

There is a procedure for brake pedal height adjustment. The adjustment screw is at the top of the foot valve. it is an allen head screw with a 13mm locknut. Screw it in till you have .16 to .32 inch of free play.. That should fix it. Make sure your air pressure is up when you do it.. I had to do mine cause the guys in our shop were gonna go the spring/ bungee cord route.. There is a right way to do most things and a wrong way to do everything.

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Jake's are usually set to disengage at 1100. Are the revs below 1100 when you let off the throttle? Throttle  must be at no fuel. Engine temp above 110. Brake and clutch full up position.

Just my 2 cents

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Engine brake should still work with brake applied but clutch pedal has to be up rpm above 1100+- engine temp up to operating temp

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Time to get out your voltage tester and do some backtracking. On my older Pete with a Cat. (doesn't matter) there's a switch on throttle and clutch.

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19 hours ago, DesertMiner said:

Sometimes the brake or clutch engage/disengage switch(s) will get old.....or the pedals are not returning to the right position.  Try putting your foot under the clutch pedal and lift up to engage the switch and see if cruise will engage.  Try the same on the brake pedal. You may have to hold both pedals to engage the switches.  Some folks have used a small bungee cord to "lift up" on the pedal(s). 

Sometimes you have to do that with new trucks too.

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Seen one fixed 2 weeks ago. His was doing that same deal. It was the on/off switch. It had gotten where it would be on. But not making contact. Tim put a new switch in for the guy. And told me they had 12 in last year. 9 of them were the switch, rest of the Clutch switch. But on those curse was acting up also.

 

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Is the ECM set so that the Jakes only come on with the service brakes? Only have to tap the brakes enough to activate the jakes then let them do the braking...you may not realize that you are doing that when they work..or it could be some of the stuff above.

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13 hours ago, porky69 said:

Is the ECM set so that the Jakes only come on with the service brakes? Only have to tap the brakes enough to activate the jakes then let them do the braking...you may not realize that you are doing that when they work..or it could be some of the stuff above.

Get a non computor truck (mechanical) and some straight pipes. You'll know if there working.

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Turns out it was the on/off switch.  I ordered the on/off and 3 stage switch from Volvo. Total cost $100.00.  Would have cost me $150 to have Volvo diagnose the problem and then add parts/labor on top of that for the repair. 

Many thanks to Pete Kildow.  Saved me a bunch of money and aggravation. 

 

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7 hours ago, Flying Finn said:

Turns out it was the on/off switch.  I ordered the on/off and 3 stage switch from Volvo. Total cost $100.00.  Would have cost me $150 to have Volvo diagnose the problem and then add parts/labor on top of that for the repair. 

Many thanks to Pete Kildow.  Saved me a bunch of money and aggravation. 

 

Glad It helped out. So often shops charge hours and hours. To track down something, when it turns out to be the simple things.

 

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