94 U280 Pac Brake Switch

Topic: 94 U280 Pac Brake Switch (Read 2521 times) previous topic - next topic

Re: 94 U280 Pac Brake Switch

Reply #25 – January 15, 2019, 07:26:11 pm

John's going to send them to me, as well. Still not sure how many of the members have them or when PB upgraded to the 'new generation'. More research is needed, on my part. Maybe you who have these will bookmark this thread and we can share questions/info?

Re: 94 U280 Pac Brake Switch

Reply #26 – January 16, 2019, 01:42:40 am

Thanks Chuck,

I was just too tired to think on my own to get it done, so thanks for the help. I hope this helps and gives some pointers on lubrication for those whom may not know. I bought the synthetic lube a while back on Amazon so it may be a good bet that is a good place to get it quickly.

Re: 94 U280 Pac Brake Switch

Reply #27 – January 16, 2019, 01:58:24 am

Toby's setup was what I had thought was originally done with mine on the rocker panel (in place of the retarder) but the wires have yet to be traced. Also, as Balcantrez mentioned about the foot switch, that was one of the options mentioned and too as Brett had mentioned about the transmission gear reduction as well could be added. It is all in how it was setup and purchased and with what options. I hope to find one of these options in my rocker switch that may have been bypassed but only time will tell. At least we now have some factory files to look at and go by and as I mentioned these can be upgraded as you wish and they give all the listings with the engine and transmission combos possible.

I know that the guys at Pac Brake will do everything possible to help in repairs to upgrades or new installs. A few days ago I felt out in left field someplace but now I have a whole library and plenty of people to help and draw info from when needed. Thanks to all and I will keep you up to date on my own outcome.

Thanks

John

Re: 94 U280 Pac Brake Switch

Reply #28 – January 16, 2019, 02:04:22 am

Here was another one that I missed. One of the must have files.

John

Re: 94 U280 Pac Brake Switch

Reply #29 – January 16, 2019, 09:37:30 am

John,

About the interface with the transmission. My exhaust brake was originally set up with this option. There is a sticker on my Allison ECU (brain box) indicating that the "automatic preselect" was adjusted to 2nd gear at request of the owner. I think the way this was supposed to work was when the exhaust brake was activated (in 6th gear) the transmission would start automatically downshifting as engine RPM/speed would allow, and work its way gradually down to 2nd gear as the coach slowed down. I say I "think" because this feature has never worked since we got the coach. That's fine with me! I would rather be in control of gear selection, and decide what gear I want when I want it.

As I mentioned in a earlier post, I have found our brake to most useful on the highway, and the best braking combo to be 4th gear at a maximum "comfortable" RPM (around 2000 to 2200). This equates to about 45-55 MPH, and is a good useful speed for descending long steep grades on the highway. I can't imagine ever needing the brake in 2nd gear, because in that gear the coach would be at crawling speed. I also never bother to use our brake in town, because it is ineffective at low engine RPMs.

My brake has a "exercise" feature that is handy. Each time we start our engine (assuming the system air pressure is 60psi or better) the exhaust brake cycles closed/open twice. This ensures that the mechanism gets operated regularly, and goes a long way toward keeping it freed up.

Re: 94 U280 Pac Brake Switch

Reply #30 – January 16, 2019, 10:03:50 am

Yes, if properly wired though the Allison ECU, the transmission will downshift as speed drops to/toward the "pre-select gear".

2nd and 4th are common options, but any gear can be programmed in. I had ours set to 5th.

At highway speeds, it does NOT downshift to 2nd, any more than at a stop light with selector in 6th it is in 6th gear. It is the "go to" gear.

I also have no problem in not wiring through the Allison and letting the driver use the down arrow to select the proper gear.

Be aware that the PacBrake PRXB is quite a lot stronger at lower RPM than the older design exhaust brakes.

Re: 94 U280 Pac Brake Switch

Reply #31 – January 16, 2019, 10:09:12 am

Quote from: wolfe10 – January 16, 2019, 10:03:50 am

Yes, if properly wired though the Allison ECU, the transmission will downshift as speed drops to/toward the "pre-select gear". 2nd and 4th are common options, but any gear can be programmed in. I had ours set to 5th.Be aware that the PacBrake PRXB is quite a lot stronger at lower RPM than the older design exhaust brakes.

To 'pre-select' (which I've never done), how is that done? BTW, I use the toggle all the time driving in town, work's great!

Re: 94 U280 Pac Brake Switch

Reply #32 – January 16, 2019, 10:21:29 am

Mike,

An Allison dealer has to reprogram the ECU using an Allison proprietary device. Not something an owner can do. Takes about 10 minutes.

Re: 94 U280 Pac Brake Switch

Reply #33 – January 16, 2019, 10:23:19 am

Quote from: wolfe10 – January 16, 2019, 10:21:29 am

An Allison dealer has to reprogram the ECU using an Allison proprietary device. Not something an owner can do. Takes about 10 minutes.

So, (unless the PO changed it) we are going to assume it's still set for 5th gear?

Re: 94 U280 Pac Brake Switch

Reply #34 – January 16, 2019, 10:32:59 am

Mike,

Correct. But, easy to confirm. Next time you drive it, turn on the exhaust brake switch and look at the LEFT shift pad window. That will indicate the pre-select gear.

If it as I had it programmed, that window will go from "6" to "5". Remember, left window is the pre-select gear (gear toward which the transmission will go), the right window the actual gear the transmission is in.

Yes, there are some years with only a single window (thanks, bean-counters). That window indicates the pre-select gear, NOT the gear you are in.

Re: 94 U280 Pac Brake Switch

Reply #35 – January 16, 2019, 10:44:04 am

Thanks, I have seen different numbers left & right, but never understood what was what. As I said, I drive in town with my hand (ergonomically placed, thank you) on the toggle switch. Only use the mains for a full stop. Are you sailing or sitting in a salior's bar?

Re: 94 U280 Pac Brake Switch

Reply #36 – January 16, 2019, 11:23:39 am

Quote from: mike leary – January 16, 2019, 10:44:04 am

Are you sailing or sitting in a salior's bar?

Update on the sailing trip: Not on the boat-- sailing a "small craft" on a time schedule is an oxymoron.

Thanksgiving to Christmas the boat was stored at Port LaBelle FL on the Okeechobee waterway-- staged to cross the Okeechobee, down to West Palm Beach and across to West End, Grand Bahamas. Arrived at the boat 12/28, ready for the 3 day trip to West Palm to await the first good weather window to cross the Gulf Stream. Neal Pillsbury was kind enough to ferry us from return of the rent car at the Ft Myers airport back to the boat. Weather looked good for a 1/2/2019 crossing.

So, 12/29 ready to head east. BUT (HUGE BUT) taking the boat across the Okeechobee requires the services of "Billy the boat tipper" to tip the 53' mast to go under the 49' Mayaka RR bridge. 26 degrees of heel and we are good to go! Billy has tipped this boat 3 times so far-- so, no big deal (we ASSUMED). Billy cancelled at the last minute-- his outboard is "broke".

This forced us to backtrack to the Gulf of Mexico and sail down through the Keys. That extra 300 miles (at 6 MPH) we had to do going through the Keys instead of across the Okeechobee Waterway ate up an extra 9 days. But, we had a great time, visiting some of our old haunts: Ft Myers, Ft Myers Beach, Marco Island, Indian Key Passage anchorage, anchorage off Little Shark River, anchorage off Matacumbe Key and in Biscayne Bay.

When we came north from the Keys and arrived at Biscayne Bay, we started looking for a weather window to safely cross the Gulf Stream to West End, Grand Bahama and on east to the Abacos. As is common this time of year, there are limited "weather windows" to safely cross both the Gulf Stream and then the 125 miles from West End, Grand Bahama to the Abacos. If we crossed on the next weather window, we would be stuck in West End at an expensive marina for at least 7 more days due to a strong cold front with 25+ MPH winds.

Our flight from Marsh Harbor was set. Unlikely we would even get to the Abacos/the island from which we had our reservation before our flight.

SO, Dianne and I got off the boat in Miami and got a rent car to drive back home. Visiting friends here before hitting the road. My brother and his wife who are not on a schedule will continue east as weather permits.

Yes, he is all set to do damage to the Lobster population.

Re: 94 U280 Pac Brake Switch

Reply #37 – January 16, 2019, 02:24:11 pm

Thanks again everyone as this is great food for thought and now know what I'm looking at when digging and tracing. I checked my photos of my ECU that I had rebuilt and it has no reprogrammed features as in Chucks marked on it so I know that was not included. It is great how much we learn from one another on these items. I really appreciate Brett jumping in when he has got so much on his plate, his words to many of us are like Yoda's. Have fun Brett!

This has given me a much better understanding of what is what and how things interact as in all the interlocks (relays) in the Pac Brake wiring, Cruise control, Air brakes, and the optional ECU settings. As mentioned I'll stick with the current install until I get it sorted and then look to maybe an upgrade. I would rather get things running properly first and to understand it and go from there. Chris at Pac Brake mentioned to "test the Pac Brake by disconnecting the power side of the Pac Brake solenoid on the engine firewall and putting power to it", only with the engine off after you have built up air in the system to see if it is closing the Pac Brake when actuated. Also, to make up a small powered test wire with a sealed illuminated switch for the test purposes from the battery and I'd probably throw in a fuse just in case and alligator clips on both ends. Then you can toggle back and forth to see if it works and you have a nice test lead afterwards. All good things to know and I feel much more knowledgeable now of what I'm looking at. I think a lot of the people that buy there coach have little understanding of this and usually don't want to admit that until they run into problems, myself included there. At least it is still fun to learn at 72 but then I may have to learn it again a few days later, memory, whats that! That on my hard drive!

Thanks,
John

Re: 94 U280 Pac Brake Switch

Reply #38 – January 16, 2019, 03:17:07 pm

Does your shifter look like this?

Re: 94 U280 Pac Brake Switch

Reply #39 – January 16, 2019, 03:28:47 pm

Yes Mike, it is the same unit there and just been serviced with the ECU last year. Still works great!

Re: 94 U280 Pac Brake Switch

Reply #40 – January 16, 2019, 03:28:58 pm

John,

Lots of "always hot" and "hot with ignition on" sources in the engine room. Be sure you disconnect the harness back to the dash/switch before applying 12 VDC positive to the PacBrake solenoid. You do not want to back-feed that circuit. You may want to cut the positive wire and install insulated male/female connectors to make testing and activating for lubing (IMPORTANT) even easier.

Re: 94 U280 Pac Brake Switch

Reply #41 – January 16, 2019, 05:44:14 pm

Great point Brett, that is what I had in mind but I did not know if it was plugged in or hard wired as you suggest. I know better than to back feed a circuit, it brings out the nasty surprises you don't want. I will take your comments as sage advice and a good reminder, thanks. After my last response I had given it some thought too in that manner as I was not sure of how the connection to the solenoid was made as I did not see any connectors in the photos of the solenoid and wiring.

Here are photos of the switches I have been mentioning. Current toggle sw. to right of ignition sw. & lighter. Also the rocker switches with the one between the Ether and Parking Brake.

John

Re: 94 U280 Pac Brake Switch

Reply #42 – January 16, 2019, 07:10:02 pm

Yours is all different than mine; any clue when it was installed?

Re: 94 U280 Pac Brake Switch

Reply #43 – January 16, 2019, 10:04:27 pm

Well--- different engine (Cummins C vs Caterpillar 3116), different cruise (his is the OE Bendix cruise, yours has been upgraded to the King Control electronic cruise) and different exhaust brake (his is the original PacBrake vs PRXB on yours).

So, yes, DIFFERENT.

Re: 94 U280 Pac Brake Switch

Reply #44 – January 16, 2019, 10:46:53 pm

I'm not sure Mike on when it was done as nobody has any paperwork or receipts for it now and nothing came with the coach from the previous owner who kept all his receipts. I believe it was done by the original owner as the second owner did not take delivery of it until 2003 which would have made it the late model Pac Brake. I know that it was based in or around San Antonio, TX until the second owner got it and then it made it's way to the Seattle area. I just assume that it was done a short while after originally sold in '94.

Re: 94 U280 Pac Brake Switch

Reply #45 – May 31, 2019, 01:24:46 am

Hi Everyone,

Here is the update on my PacBrake malfunctioning.

Finally got it all sorted out and it is working again as it should as I had a place to work and enough time to dig into the wiring. I found out that the second switch installed to activate the PacBrake was not necessary work done for the previous owner. I traced the wires and found that they were perfectly intact and functioning to the illuminated rocker switch by the Parking Brake. All that was needed was a new switch as the original throttle switch by the fuel pump had come close to seizing buy still worked if you used pliers. The previous repair by the previous owner could have cost much less if they had done the switch replacement instead of freeing up the switch, but they installed a new multiconductor cable front to rear that was unnecessary plus the toggle switch on the dash. I can possibly find a use for the wiring but the switch will disappear and something else will go in that hole in the dash. I bought a new switch which is a different type from PacBrake to activate the air solenoid to the PacBrake at the rear. The actuator assembly is now on the accelerator pedal and engages the PacBrake when your foot is lifted off the accelerator and as soon as you press the accelerator pedal disengages. It was an easy thing to do once I gave it enough thought and found out the wiring was all there and just needed to be moved to accommodate the new switch on the accelerator. Now I feel that I can safely go into the mountains and know that the PacBrake is there when needed.

I also found hidden was a broken return spring on the throttle cable on the fuel pump and have a new pair coming from FOT to replace them both.

I want to thank all, Chuck & Jeannie, Mike & Pamela, Brett Wolfe, Mike Leary, and Old Phart Phred, who stepped forward to help with ideas and suggestions. The Forum is always a great help when help is requested. It gives us confidence and knowledge to get it done. It was all very simple once I got past the creative unnecessary creative wiring and removed all the old setup at the fuel pump.

John Smith

PS: I just gave my coach it's name today, Roamer, after the friendly neighbors cat stopped by to say hello and was killed shortly thereafter by a careless driver. Here's to Roamer, he will always be loved and remembered by us!

Re: 94 U280 Pac Brake Switch

Reply #46 – May 31, 2019, 05:08:37 am

John,

That looks a lot more proper than the other activation switch that you had. With this one in the clean/dry environment where it is mounted it should work for a long time. That is a very good idea for a mounting box also.

Mike

Re: 94 U280 Pac Brake Switch

Reply #47 – May 31, 2019, 08:36:06 am

Excellent photo report, and nice clean installation of the activation switch! Now you can check this item off your list, and move on to the next project. There is ALWAYS another project!

PS: Exhaust brakes like to be exercised. Even if you are not driving in the mountains, try to operate the brake several times on every drive. Doing so will keep the parts in good condition and ready for the times you really need them.

Re: 94 U280 Pac Brake Switch

Reply #48 – May 31, 2019, 08:59:34 am

Do you still have a way to turn off the exhaust brake (like a dash switch that then powers the switch on the accelerator)?

To me, that would be critical, as without it you miss my favorite "gear"= COASTING. Said another way, you don't want the exhaust brake to come on every time you close the throttle.

And, it the exhaust brake wired through the transmission so it automatically downshifts when the exhaust brake is activated?

Re: 94 U280 Pac Brake Switch

Reply #49 – May 31, 2019, 11:55:39 am

I agree that coasting is an important part of going downhill too. The way it was configured was the same way that I wired it until I can either find a way of wiring it the way you mentioned but for now I have a nice big red light that is come on on the dash that will not let me forget to shut it off as I had done in the past when not needed and I may put a flasher on the indicator light if needed. If I could get some info on the way it should be wired I could easily wire it to suit but there again I would have to check the ECM to make sure the unit is configured to operate that way. I have just been down shifting till this point as needed.

To this end, now it it is operational and a little safer and easier on the service brakes descending steep grades. As you very well pointed out Brett it would be better done the way you mentioned and it will get there. At least, until I can get further info I have something useful to use in a manual mode. Right now I'm just happy having the wires sorted to the point of knowing what I have is functional and a basis for any further mods. I found if modifying a non functioning item you are guessing at the outcome if it doesn't work the first time. That I found on the wiring I did this time after testing all the wires and hooking up the new switch and not looking at the contact point on the switch as it should have been NC contacts and the switch was wired with NO contacts. I knew right where to look and it took me about 10 minutes to rectify the problem but at least I understood what had happened. So if someone does buy that switch from PacBrake for the same use as I had then they will have to remove one contact screw and move it to the opposite side of the switch to function properly. If I had not checked things out to start with I would have been guessing again as to what happened. So as I found out years ago it is better to start clean with a good base and proceed from there. Now, I'm good to go again for any mods that I can add to make it better.

Thank you again Brett for pointing that out as it will keep me doing something in my spare time. I appreciate all the comments everyone have given. You never know where they may lead you and sometimes someone may discover a better way to get things done and that way we all can learn. If I can't learn I'm dead!

John

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