Cummins ISL & Jake brake operation on cruise control?

[John_Canfield]

Those of you with the Cummins ISL and Jake brake - do you remember if the Jake operates going downhill with the cruise control set?

I think ours did but doesn't now, but that could have been another hallucination .

Pretty sure I have read that some chassis manufacturers have the Jake operate while on cruise but I'm not sure about Freightliner.

Thanks!

[John_Canfield]

Those of you with the Cummins ISL and Jake brake - do you remember if the Jake operates going downhill with the cruise control set?

I think ours did but doesn't now, but that could have been another hallucination .

Pretty sure I have read that some chassis manufacturers have the Jake operate while on cruise but I'm not sure about Freightliner.

Thanks!

[Toterman (David)]

Hi, I do not have a cummins in a MH but in my Volvo it is a choice you can make as to weather it works or not. I had mine turned on the last time I took it to the shop and they hooked thier puter to it. When I get 5 mph over it comes on and slows me down. Pretty neat

David

[SargeW]

Hi John,

In the MH version of the Cummins, the cruise is inhibited while the cruise is on. This is specifically designed to prevent the brake from coming on when the MH picks up 2 or 3 MPH on slight downgrades. The Cummins I had in 3 past trucks all came on if the veh picked up speed.

However, the brake on our vehs is the Variable Vane Turbo (VVT) providing the back pressure. On the pre 07' Dodge trucks the brake was a butterfly valve in the exhaust after the turbo. I do believe that changes in the 07' Dodges though.

The VVT brake is much more responsive than the other version of the exhaust brakes. It would be a huge waste if the VVT kicked in on every small speed increase. The answer is to keep a thumb on the "cancel" button on the cruise. If you start picking up too much speed on a downhill, canceling the cruise will immediately throw on the VVT. I have purposely allowed the speed of the MH to increase 10-15 MPH on a downgrade if another big incline is coming. As long as the cruise is set, it will inhibt the VVT.

Sarge

[Harry B]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Cummins ISL and Jake brake - do you remember if the Jake operates going downhill with the cruise control set </div></BLOCKQUOTE>

John,

I have the 2005 Horizon as well and my engine brake did not engage going down hill while in cruise control mode.

It may operate different now that I have had the Jake brake reprogrammed. It now comes on when the brake pedal is depressed vs just releasing the trottle.

I'll ahve to check that operation when I get back out again. Should be getting back on the road to Florida in about a week since the rains will start soon in Seattle.

[Mike Lutz]

I have a Freightliner/Cat 330. The jake break definitely works with the cruise on. I shut the jake off while on the highway-or you get the surprise of your life when taking you foot off throttle or going down a grade

[John_Canfield]

Thanks for the responses fellows! Like Sarge suggests, I found that just hitting the cancel button going downhill will cause the Jake to engage. I like to pick up 5-10 mph going downhill assuming it is a straightaway going up the other side.

Sarge - we have the high/low compression brake with the ISL engine. In the low setting it uses three cylinders, high is all six. It has to be a pretty good grade or a very long grade to need the high position.

[rnabors]

Hello John,

On mine the Jake is not operative when the cruise is on. A tap of the brake or pushing the cruise cancel button will make the Jake brake operational.
Hope you are doing well.

[GreyDog]

I have an 05 Vectra. The Jake definitely engages while the cruise control is engaged. In fact, the operation is smoother than normal operation. I like the notion of reprogramming the Jake to operate when then service brake is applied versus release of the throttle.
John, you are absolutely correct in your understanding of the Jake operation in the HI/LO modes. I live in the Western US and have travelled every major mountain grade in the Sierras, Cascades, and Rockies. I have only needed to use the HIGH setting one time. The compression braking capacity is so effective in the LOW setting.

[Joe-K]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by GreyDog:
I like the notion of reprogramming the Jake to operate when then service brake is applied versus release of the throttle. </div></BLOCKQUOTE>

Greydog,

I'm not sure if you noticed This BrakeSwitch Thread yet, but this past weekend a couple of us installed the BrakeSwitch product into our motorhomes. It changes the operation of the exhuast brake to function the way you are describing. It turns on with application of the service brake rather than by releasing the throttle.

[Techie]

ours kicks in when it gets to about 8-10 mph above the cruise setting

[rnabors]

Ops---I was wrong in my response. On the way home today I tried the Jake brake with the cruise on. Indeed the Jake will come on very very smoothly when going downhill helping maintain the cruise speed.
I usually turn the Jake off after use and miss spoke in my first response.

[John_Canfield]

Do you have the Spartan or Freightliner chassis?

[rnabors]

I have the Spartan chassis.