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Automobilist · 03-06-2011, 08:30 PM

Our 2002 Winnebago Journey has a really nice Cat 330, with Allison 3000. My question concerns the exhaust brake operation. When activated, it's very abrupt in operation. really aggressive. So much so that it makes the ride jerky. consequently, I rarely use it, except in steep mountains, and then usually only for short periods of time, it's just not comfortable. Anything that can be done to make it a bit smoother?

Ed

azloafer · 03-06-2011, 08:49 PM

Quote:

Originally Posted by Automobilist

Our 2002 Winnebago Journey has a really nice Cat 330, with Allison 3000. My question concerns the exhaust brake operation. When activated, it's very abrupt in operation. really aggressive. So much so that it makes the ride jerky. consequently, I rarely use it, except in steep mountains, and then usually only for short periods of time, it's just not comfortable. Anything that can be done to make it a bit smoother?

Ed

We have a cummins with an Allison 2500 and the same exhaust brake that you have. I would agree that it is a little harsh and when using it in town it causes the coach to be jerky as it cuts in and out. Even so, I think that it will save on heavy braking. I don't have to use the brakes as hard with the exhaust brake on. It stays on until the speed of the coach drops below 15 MPH. So if I am driving at 45 MPH and see that the light is changing to red a short distance ahead, I just tap the brake and the exhaust brake comes on to slow the coach until the speed drops below 15 MPH and then I have to actually brake. I guess I can live with some of the mild jerking. I have experimented with using it on for an hour trip and then not using it for an hour. I prefer to use it and live with the small jerks. I doubt if there is any way to make it smoother.
Happy Trails, Joe

BobGed · 03-06-2011, 09:26 PM

Might want to talk to your Cat dealer about to see if the following might give you a smoother operation:
The ECM can be programmed by your Caterpillar Dealer to operate in three modes;
Coast Mode, Latch Mode and Manual Mode. With the cruise control turned on, you
are able to select A or B.
A Coast Mode: engages the Pacbrake when the service brake pedal is applied and
disengages when the pedal is released.
B Latch Mode: engages the Pacbrake when the service brake pedal is applied and
remains on after the pedal is released. The Pacbrake disengages upon activation of
another input such as depressing the throttle or clutch, or when engine speed
drops below 800 RPM or when the Pacbrake switch is turned off.
C Manual Mode: Does not require the cruise switch to be on and operates the
Pacbrake manually at the driver’s discretion.

HarleyWJones · 03-09-2011, 10:48 PM

I use a device called the "Brake Switch". My exhaust brake used to come on when braking and while coasting. (as long as the dash switch is on). The "Brake Switch changed that to a much more pleasurable experience.

Now with the switch on, the exhaust brake doesn't apply until the brake pedal is tapped or depressed, and stays on until my speed drops below 15 mph or the throttle is tapped or depressed. Depressing the throttle and then releasing it allows me to coast. This is pretty much the "Latch" mode that Cat can flash. I compared the expense of having the ECM flashed vs the "Brake Switch" and the add-on was the clear winner. Now I can leave the exhaust brake on in town and the constant jerking is gone. It coasts when it should. Just tapping the brake pedal at the top of a hill applies the exhaust brake and it stays on unless you tap the throttle.

Basically you have to supply the control box with the brake light power and a ground. All the wires I needed were right under the dash. There are two pairs of wires that you use to interrupt the line to the dash switch. Some installations require both pair, but mine used only one. Of course the device only works with the dash switch on.

I installed it myself in about 30 minutes. The control box is about 2 by 3 inches. (Picture below) Also if you don't like the way it operates, all you have to do is remove it and you're back to the old system. No need to pay Cat again for a re-flash, and only the purchase price is wasted. I can't imagine wanting to go back to the old way.

Seems like it was about $80 and $5 shipping. It was a good investment for me. I have no affiliation with the product, just a happy user.

BobGed · 03-09-2011, 10:58 PM

I installed the Brake Switch on my Cummins and love it, however my understanding is that if you have a Cat engine you can accomplish pretty much the same thing with a dealer reprograming of the ECM as I previously posted.

HarleyWJones · 03-10-2011, 12:03 AM

Quote:

Originally Posted by BobGed

I installed the Brake Switch on my Cummins and love it, however my understanding is that if you have a Cat engine you can accomplish pretty much the same thing with a dealer reprogramming of the ECM as I previously posted.

BobGed, thanks for your input.

You are correct, but the price they gave me for the flash was $150 and possibly more, depending on my current firmware version. It is also irreversible unless you pay them to flash it back to the way it was.

That's why the add-on worked better for me.

BobGed · 03-10-2011, 12:37 AM

Yikes...$150, I don't blame you for going with the Brake Switch. I thought it was free, but maybe only if you were having other work done.

Homer was offering a 25% discount to FCOC members if you ordered directly from him, but I don't know if that is still in effect.