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Jake Brake questions

When we had the coach out for the inspection I tried using the Jake brake. Nothing. The switch moves from off to middle to high easily enough, but no red light comes on. I've been told that the Jake brake only works with the foot brake, so I put the switch in the middle position (I assume that is using three cylinders) and put my foot on the foot brake. No light, and no obvious engine braking. Got back up to 60, moved switch to the high position and put my foot on the brake again. Still so light or obvious engine braking. I spend some time tonight searching all three notebooks but didn't find anything on the Jake brake. Lots of other interesting reading, though. Service brakes work well, but I'd like the Jake brake to work, too.

Possibly related to his is that the cruise doesn't work. Switch moves, but the speed doesn't hold. The whole turn signal lever/cruise control looks like what we had in an old Oldsmobile years ago.

Questions: Is there a fuse/breaker somewhere? If so, where might it be? Would there be some common failure point that would knock out both the Jake Brake and the cruise control?

I'm assuming that there actually is a Jake brake installed on this coach. Where might it be located, and what does it look like? Tomorrow I'm going to spend some time outside on various projects, and the coach is part of that effort.

Re: Jake Brake questions

Reply #1 –
David,

Not sure if your cruise control is the same as mine since you are a year newer but on mine you move the slider switch on the stalk of the turn signal towards the end of stalk. This turns on the cruise. To set the speed you need to turn the knob at the end of the stalk clockwise and let go. (looking at the end of the turn signal) This will set the speed to whatever speed you are traveling at the moment. To adjust speed turn knob CCW to speed up and CW to slow down. You can call also fine tune the speed up or down by 1 mile an hour by quickly twisting the knob and letting go.

The above is dependent on the cruise being in working condition. :)

see ya
ken
The selected media item is not currently available.ken & dori hathaway & Big Agnes
🍺1992 U300 GrandVilla WTBI #4150 FOT FBP 2011
✨6V-92TA DDEC Parlor Coach 350HP Series 92
🏁2011 Nissan XTerra Pro-4X

Re: Jake Brake questions

Reply #2 –
The Jake on a 6V92 is a solenoid operated device to alter the exh valve train geometry which provides substantial auxiliary braking. It is internal to your engine. Lo/Hi means 3 or 6 cylinders actuated. Any DDA facility should be able to troubleshoot it in short order.

The Operation of the Jake Brake Engine Brake - YouTube
The selected media item is not currently available. Dave Head & Megan Westbrook
Titusville, FL - The Great Outdoors
'98 270 buying this month
Toad is a 2018 F150 XLT

Re: Jake Brake questions

Reply #3 –
We are between sets tonight but the Jake works independent of the brakes. Just take your foot off the fuel and it comes on. leave window open and you can hear
 it. Check fuses.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Jake Brake questions

Reply #4 –
And what it sounds like when it is working:
jake brake
1994 U225
build #4514

Re: Jake Brake questions

Reply #5 –
David,

Here are Foretravel schematics A3375 and A3376. Let me know if this covers it or if you need any others.

Do you have any of the factory schematics?

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Jake Brake questions

Reply #6 –
The second schematic shows a 10 Amp fuse powering the retarder circuit. Looks like a good place to start.
Tom Lang K6PG (originally  KC6UEC)
and Diane Lang
2003 38 U295 build 6209
2016 Jeep Grand Cherokee Summit Ecodiesel
still have tow-ready 2006 Acura MDX 
Temple City, California
Motorcade 16681 California Chapter President
SKP 16663 member of SKP Park of the Sierra, Coarsegold California
FMCA F071251
Retired electrical and electronic engineer

Re: Jake Brake questions

Reply #7 –
Quote from: kb0zke –
When we had the coach out for the inspection I tried using the Jake brake. Nothing. The switch moves from off to middle to high easily enough, but no red light comes on. I've been told that the Jake brake only works with the foot brake, so I put the switch in the middle position (I assume that is using three cylinders) and put my foot on the foot brake. No light, and no obvious engine braking. Got back up to 60, moved switch to the high position and put my foot on the brake again. Still so light or obvious engine braking. I spend some time tonight searching all three notebooks but didn't find anything on the Jake brake. Lots of other interesting reading, though. Service brakes work well, but I'd like the Jake brake to work, too.

Possibly related to his is that the cruise doesn't work. Switch moves, but the speed doesn't hold. The whole turn signal lever/cruise control looks like what we had in an old Oldsmobile years ago.

Questions: Is there a fuse/breaker somewhere? If so, where might it be? Would there be some common failure point that would knock out both the Jake Brake and the cruise control?

I'm assuming that there actually is a Jake brake installed on this coach. Where might it be located, and what does it look like? Tomorrow I'm going to spend some time outside on various projects, and the coach is part of that effort.
You can do a lot of troubleshooting on your own. study the schematics. when I had similar problems I drew out a seperate diagram with only the jake and related circuits and worked from there. There are relays that also in the circuit. The jake on my coach is also tied into the antilock brake and the cruise. The jake is looking for a ground to complete the circuit. I posted some of my experiences, do an advanced search under "Jake brake" and "Rick" as the author.
You should be able to test the jake without movin the coach. Just rev the engine up to 1500 + rpm, get off the pedel, flip the switch and listen.
Good luck,
Rick

Good luck,
Rick

Re: Jake Brake questions

Reply #8 –
The Jake on our coaches is not near as loud as it is on the big trucks. Ours goes through the turbo then through a large muffler. Plus the exhaust is about 40 feet away from you pointing the other direction.

@Rick I'm not sure if the rev up to 1500+ then let off will work. When I have the Jake on and I pull up to a sotp sign I can hear the Jake kick out when the coach slows to about 10mph. I think the coach has to be moving before the Jake will kick in. Of course I could be wrong. :) I leave Monday morning so I'll test before I take off.

see ya
ken
The selected media item is not currently available.ken & dori hathaway & Big Agnes
🍺1992 U300 GrandVilla WTBI #4150 FOT FBP 2011
✨6V-92TA DDEC Parlor Coach 350HP Series 92
🏁2011 Nissan XTerra Pro-4X

Re: Jake Brake questions

Reply #9 –
David,

Should have mentioned but it was really late, that a couple of years earlier, U300s had transmission retarders and it looks like the name of the dash switch and terminology on the schematic did not change, but you do have a Jake brake if yours is a 1993 regardless what the dash switch says.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Jake Brake questions

Reply #10 –
Thanks for all of the help. I'm going to spend some time today in the coach seeing what I can find.

Pierce, I have very few schematics. I don't know if they were supposed to be in one of the three binders or whether they are things that owners have to get on their own.

Given all of the electrical problems this coach has (monitor out, speedometer out, Jake out, cruise out) I suspect that finding, cleaning, and tightening all of the grounds would probably go a long way toward solving the problems. I did see in one of the schematics that I do have that there is a fuse in the monitor. I wonder if that may solve the monitor problem.

Time to go to work.

Re: Jake Brake questions

Reply #11 –
David,

I was making PDFs of all the electrical schematics for Berry. Will send copies to you also. Have had a foul cold with bathroom remodel at the same time but will get them done and out to you early this next week. They are for U300 and U280 but some of the info should be good for other GVs.

Yes, one of the original big thick binders originally came OEM with all the schematics in it. Once you get the PDFs (or the two I posted), go to Kinko's and have them blown up. Then roll them up, put them in a mailing tube and store the tube in an overhead compartment. Really reduces the stress as they are MUCH easier to read, especially in low light. Bill Chaplin gets the credit here as he made me a large schematic for the 12V system when he came to visit. I just hate giving someone else the credit. :))

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Jake Brake questions

Reply #12 –
Thanks, Pierce.

Re: Jake Brake questions

Reply #13 –
David,

Here are the rest except for the two B2035 & B2126 schematics. They are too large to post and I didn't want to lose any resolution so all the wire codes/colors could be read so I will email them to you. Anyone else may PM me and I will be glad to email these also.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Jake Brake questions

Reply #14 –
David,

You need to check to see if the rocker switch bulb for the jake is burned out.  Several of my rocker switch bulbs had to be replaced when I got my coach and probably yours too.  The Jake switch will not light up until the ignition is on to check.  The bulb comes out easily and is inserted on top of the switch from behind.  You have to lift the dash cover (use a stick to hold it it up) to get behind it. Depress the top and bottom clips to push it out of the panel.  You may have to remove the one on top of it to get to the jake switch because of all the wiring and don't try to force it.  Barry Brideau has an excellent write up with pictures on how to remove one.  Rocker Switch Bulb Replacement

Just remember the light only tells you that the switch is in the on position and the road test will tell you if it is working. Open your driver side window and listen for it.  It works better at higher rpms on all six cylinders and you should really be able to hear and feel it when the coach has downshifted back to first gear.  It will feel like you are breaking with your foot off the break pedal.  It took me a couple of drives before I really became aware of it.  After that you will know the difference and will always want to have it on.

Good luck,

Jerry

The selected media item is not currently available.
Jerry and Cindy Maddux
1993 U300/36WTBI DD6v92TA
build 4271  "Miss Lou"
1995 suzuki sidekick 4x4 toad
Gulfport, Ms

"Pride of Ownership"

Re: Jake Brake questions

Reply #15 –
Quote from: kenhat –
The Jake on our coaches is not near as loud as it is on the big trucks. Ours goes through the turbo then through a large muffler. Plus the exhaust is about 40 feet away from you pointing the other direction.

@Rick I'm not sure if the rev up to 1500+ then let off will work. When I have the Jake on and I pull up to a sotp sign I can hear the Jake kick out when the coach slows to about 10mph. I think the coach has to be moving before the Jake will kick in. Of course I could be wrong. :) I leave Monday morning so I'll test before I take off.

see ya
ken
Ken,
The jake will activate on my CAT3176b with the coach stationary as long as the RPM is high enough and you are quick with the switch. Not sure about other engines. Maybe somebody can try it and let us know.
Rick