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ghall7876 · 07-29-2021, 04:22 PM

Quote:

Originally Posted by Notn2bars

Fortunately we haven't been in a situation where the pacbrake has been needed. Unfortunately it doesn't work. While at home I discovered the pacbrake was frozen and the valve was stuck. Took everything apart, cleaned and lubed. Worked well on the bench. Reinstalled in the MH. Checked the air valve that operates the pacbrake and it was functioning as it should. While on the road Sunday tried to operate the pacbrake with the foot switch on the floor to the left of the steering column, nothing. My foot was off the throttle, cruise control off, and engine at idle. Any ideas as to what might be the issue? Is there a way to check the operation of the pacbrake while not moving? At a lose as to what to do, and very concerned about not having an operational pacbrake. Your help is greatly valued and appreciated.

it's more then likely it is the foot switch

JVH · 07-29-2021, 05:19 PM

My 1995 Eagle is very old school. My pacbrake does not have a foot switch.
It has a dash toggle switch. When on it engages when I take my foot off the throttle.
It closes my pacbrake and downshifts the transmission to 2nd gear.
If I touch the throttle it opens and goes back to D for drive.
I can sit in the driveway, open the bed and flip the control switch off and on. I can hear the pacbrake close and open. To test the trans functions I must be rolling.

Notn2bars · 07-29-2021, 08:18 PM

ghall7876, the foot switch has tested good. It reads 14 volts on one side of the switch and 14 volts on the other side when the switch is activated. I wish it was the switch, that would be an easy fix. Harry, I called Pacbrake today and talked to a technician. Told him that the the piston was slow to return to to the deactivated state. He indicated that there is a small weep hole on the bottom of the air solenoid that allows the air to escape when voltage to the cylinder is cut. Sometimes it gets filled with dirt, oil and etc. and doesn't allow the air to escape. Didn't get a chance to pull the solenoid off and check it today. Working on the Liberty instead. The swivel works well, it is under the item part that could be a filter. Will post the results.

wolfe10 · 07-29-2021, 08:23 PM

Quote:

Originally Posted by JVH

It closes my pacbrake and downshifts the transmission to 2nd gear.

Correction. Your Allison does not downshift to 2nd at road speed. What it does is downshift TOWARD 2nd gear as soon as it will not over-speed the engine in the next lower gear.

Pretty similar to your Allison shift pad showing "6" at a stop light. You are not in 6th gear-- that is just the gear it will shift toward as conditions allow.

Happycarz · 07-29-2021, 11:24 PM

My stem of the three way solenoid is up and I can see if it is plugged. Sounds like PacBrake is on same page as me.

Notn2bars · 07-30-2021, 12:14 PM

God is awesome! The pacbrake is working mechanically. Now I just have to be able to energize it. Should be fairly simple. Here a some pics. In the first pic I disconnected the air line from the solenoid and tested the piston using air from the compressor in the garage. It worked perfectly. Closed and opened the butterfly as it should. So, the problem was in the solenoid. In the second pic used a 3/16 Allen head socked and 2 long extensions to disconnect the solenoid from its mount. In the third pic the solenoid is on the bench. The only hole I could find was the one on the top of the solenoid. Used a small drill bit to clean it out. Then sprayed carb cleaner into the fitting that attaches to the air line to the cylinder, thus in the same direction of the air when solenoid is deactivated. Hooked it all back up and it worked perfectly. Next will be wiring it to a switch on the console.

Hope this helps any others experiencing the same type of issues.

wolfe10 · 07-30-2021, 12:21 PM

In terms of signal from the driver's area, does the Allison shift pad go from "6" to some lower gear (often 2nd or 4th) when you engage the exhaust brake? That is the first step in the process.

If not, first suspect is that the throttle position switch is not showing "closed throttle".

Notn2bars · 07-30-2021, 01:02 PM

Brett, it is not being activated by the foot switch near the column. At this point I haven't seen anything on the shift console. Do you happen to know where the throttle position switch is located? Also, is the relay labeled (engine retarder) the relay for the pacbrake? Thank you soooo much for keeping up with my thread. You have been such a big help. God Bless,
Ed

r3meyer · 07-31-2021, 09:24 AM

Quote:

Originally Posted by Notn2bars

Brett, it is not being activated by the foot switch near the column. At this point I haven't seen anything on the shift console. Do you happen to know where the throttle position switch is located? Also, is the relay labeled (engine retarder) the relay for the pacbrake? Thank you soooo much for keeping up with my thread. You have been such a big help. God Bless,
Ed

Have you removed the foot switch out of the equation yet? Both of my foot switchs showed just fine. 12v in and 12v out but they would not pass current. It was not until I removed it and wired in a simple on and off switch for testing that my pac brake and trans started working correctly.

There are a million threads about the foot switch failing.

Notn2bars · 07-31-2021, 09:52 AM

Thanks to all of you for your input on this thread. Today, was able to get back to work on the MH. Tried changing out the engine retarder relay. Put in a new relay put ignition switch on acc and hit the foot switch. Nothing happened. Put the old relay back in. Took the MH out on the access road to see if the shift pad would indicate anything. Lo and behold when I hit the foot switch it showed that it was going to shift toward 2nd gear. I've never seen any change on the shift pad before. There was a definite change in the feeling of the coach. Couldn't tell if the pacbrake was activating. Went home and asked DW to go back out with me so she could watch the pacbrake. Took her up to 60 mph hit the foot switch. Shift pad showed 2nd. But no word from the DW. Hit foot switch again and she yells, "it's working." Tried it several more times. The shift pad always goes to 2nd and the MH starts downshifting, but a few times the pacbrake didn't activate. Will try again tomorrw. See if things become more consistent. Any ideas on the inconsistency?

wolfe10 · 07-31-2021, 10:02 AM

If the exhaust brake has not been used in awhile, it may be mechanically sticking. Be aware that they can stick OPEN or CLOSED.

If PacBrake, have you lubed it? https://pacbrake.com/product/c18037-superlube/

Easy to tell if it is working:

Down arrow transmission to, say, 4th gear and accelerate to higher end of RPM range. Take your foot off the throttle (coast). Apply exhaust brake, turn off exhaust brake, repeat. You would feel a real difference, particularly at higher engine RPM.

Notn2bars · 07-31-2021, 10:10 AM

r3meyer, appreciate your input. I am thinking of doing exactly that and take the foot switch entirely out of the equation. Did you you use the 2 wires that went to the foot switch originally or did you run new wiring? Probably put a rocker switch on the left side console. It has one space left with a dummy cover. God Bless and have a great day.

Mile Marker 42 · 07-31-2021, 10:26 AM

Quote:

Originally Posted by TRH299

How did you free up the butterfly mechanism? Mine has never worked, but trans downshifts when switch is on and foot is off throttle. I tried moving valve by hand, but it is seized. Was hoping I could unstick it some how by tapping with hammer or twisting with pipe wrench or something working through bedroom hatch above and without removing it.

They stick open all the time from non use. Much better an easier to take it off and work on it on a bench. Easy to get off for a guy like you. If you get it unstuck and don't plan on much mountain driving, chances are you'll be fine. If you plan on lots of mountain driving, id highly recommend you replace it with their newer upgraded version. I replaced all my brakes including rotors and calipers and my rotors were badly cracked. I'd never seen that and i was an auto mechanic for many years. First trip out after brake job going down a 10% grade with my tow car on back, I couldn't stop. Luckily, I got it stopped and all 4 brakes were smoking. Finished our trip, got home and found pacbrkae stuck open. I bought their newer version and installed it. Works great And i use it all the time.