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Volunteer · 10-24-2014, 11:14 AM

I still have my "well-experienced" 1996 Discovery with a Cummins B5.9 pushing me down the road every month. This particular Fleetwood product came with a Jacobs Extarder Compression Brake Cummins B5.9 Series. It is switched on and off by a toggle switch on the dash. Problem is, the toggle switch still opens and closes the circuit (checked with a meter) but the Extarder is stuck in the "On" position. Does anyone know how to make it stick in the "Off" position? I would rather have it off than on all the time due to my personal driving habits.

wowlites · 10-24-2014, 11:23 AM

Volunteer
If it's an exhaust brake that is mounted in the exhaust downstream of the turbo it sounds like the pivot shaft for the butterfly valve is stuck or seized. Try disconnecting the actuator from the pivot lever and see if the valve moves freely for starters.
hope this might help.
Cheers
Rick T.

dennis45 · 10-24-2014, 12:21 PM

Quote:

Originally Posted by wowlites

Volunteer
If it's an exhaust brake that is mounted in the exhaust downstream of the turbo it sounds like the pivot shaft for the butterfly valve is stuck or seized. Try disconnecting the actuator from the pivot lever and see if the valve moves freely for starters.
hope this might help.
Cheers
Rick T.

Bang on Rick.

DonL · 10-24-2014, 09:37 PM

By "stuck in the on position" do you mean that the extarder butterfly is stuck closed, or do you mean that the circuit remains energized causing the extarder butterfly to close each time you let off the throttle?

Volunteer · 10-25-2014, 07:29 AM

It's acting like the switch is always on, meaning it downshifts every time I let off the accelerator. Since I've never had a seizing problem before, I just presumed the circuit was "stuck" in a way that caused the extarder to always be on. Guess I was looking for a known fuse or wiring problem for this model. I'll be sure to get someone to look at the butterfly for me. A sticking valve sounds logical to me.

DonL · 10-25-2014, 09:02 AM

Your problem is electrical, not mechanical. If the extarder valve is seized shut, you would experience a serious loss of power. What chassis is your coach on? Do you have wiring diagrams for it? I would look first for a relay that has failed in the energized position.

mel s · 10-25-2014, 09:29 AM

Quote:

Originally Posted by Volunteer

I still have my "well-experienced" 1996 Discovery with a Cummins B5.9 pushing me down the road every month. This particular Fleetwood product came with a Jacobs Extarder Compression Brake Cummins B5.9 Series. It is switched on and off by a toggle switch on the dash. Problem is, the toggle switch still opens and closes the circuit (checked with a meter) but the Extarder is stuck in the "On" position. Does anyone know how to make it stick in the "Off" position? I would rather have it off than on all the time due to my personal driving habits.

Volunteer
The Jacobs Extarder is a Jacob's brand "exhaust brake", (not a "compression brake").
Follow the excellent advice given thus far for exhust brakes.
Mel
'96 Safari

Ray,IN · 10-25-2014, 08:27 PM

You may have to disassemble the E-brake to free-up working parts. When you get it moving, lubricate with special high-temperature stuff from Pacbrake.

rag_ftw · 10-25-2014, 09:34 PM

I agree with DonL that it sounds like an electrical problem not mechanical. If your brake comes on every time you let off the accelerator it is working correctly and the butterfly is NOT stuck. "You are just not able to tell the extarder you don't need its services at this time!" If it were me I would pull the toggle switch on the dash. If the switch is good and all wires are connected I would check for a relay close to the extarder that may have failed. When you find the relay excite it with a separate source of 12 VDC power to see if the actuator will operate. If you can get your hands on a wiring diagram or electrical print it would make the treasure hunt a lot easier! Some of the smarter guys on this forum will be able to tell you if the extarder needs elec power to operate or if its failure mode is on.
Let us know how you solve the problem as we might have the same thing happen to us in the future.

Volunteer · 10-26-2014, 06:50 AM

I have the wiring diagram and will try to get my feeble mind to understand it. My original hope was that someone else may have had this same problem with an old mechanical Cummins and might know a few hiding places for a relay ... other than the usual suspects.

Mel S, I don't doubt you know what you're talking about but I copied the printing from the label attached to my Discovery's dash and it said exactly what I put in my original post, word for word.

mel s · 10-26-2014, 07:40 AM

Quote:

Originally Posted by Volunteer

Mel S, I don't doubt you know what you're talking about but I copied the printing from the label attached to my Discovery's dash and it said exactly what I put in my original post, word for word.

Volunteer
Not always

...(but I'm always willing to learn).
Thanks for the lesson.
Mel

Ray,IN · 10-26-2014, 09:54 AM

Friends, he said in his original post He's already tested the electrical circuit and it works.That, IMO means the problem is mechanical..

1mainiac · 10-26-2014, 10:08 AM

There is a switch in the throttle as well which activates the system when your driving it. The dash switch arms it but as you say it is remaining armed and comes on every time you let off the throttle. The throttle switch would be my next place to find as you could dis able it there or splice into it and add a over ride to it. My bet is that will be located on the engine which is where I would of put it. That way it would not be affected by poor linkage or a bad throttle cable.

ShapeShifter · 10-26-2014, 10:16 AM

Quote:

Originally Posted by Ray,IN

Friends, he said in his original post He's already tested the electrical circuit and it works.That, IMO means the problem is mechanical..

Actually, it sounds like he's tested the SWITCH and it works, but he hasn't necessarily tested the whole circuit. What does the switch control? Is there a relay in there somewhere that may have failed? Is there a control board? Is there a problem in the wiring going to the relay or control board? What triggers the brake when the accelerator is released, is that working? And so on?

Until the entire circuit is traced all the way to the final actuator, one can't say that the electrical circuit is fully tested.