Community Forums

steined · 10-06-2015, 12:06 PM

I've been tracking down why my PACbrake isn't engaging for about two weeks now. I have one or two more leads (no pun intended) to check, but am about to set out on our first trip into some mountains.

It will also be my first trip towing a car for a long distance.

I am going from Northern Ohio to Outer Banks NC. It is suggested I go 76 to 70 around DC to 95 the on south.

Is this something that can be done safely without an exhaust brake? If I can't figure it out before the trip, I'm wondering if I should leave the TOAD behind.

I do have an RVi2 brake installed in the TOAD, however those brakes can overheat just as much as the MH brakes I'm sure.

Will engine braking be enough should I not be able to figure it out?

Thanks!

Pigman1 · 10-06-2015, 12:22 PM

Quote:

Originally Posted by steined

I've been tracking down why my PACbrake isn't engaging for about two weeks now. I have one or two more leads (no pun intended) to check, but am about to set out on our first trip into some mountains.

It will also be my first trip towing a car for a long distance.

I am going from Northern Ohio to Outer Banks NC. It is suggested I go 76 to 70 around DC to 95 the on south.

Is this something that can be done safely without an exhaust brake? If I can't figure it out before the trip, I'm wondering if I should leave the TOAD behind.

I do have an RVi2 brake installed in the TOAD, however those brakes can overheat just as much as the MH brakes I'm sure.

Will engine braking be enough should I not be able to figure it out?

Thanks!

Have you had any experience driving mountains, with or without the PAC brake? Your coach will be fine in the mountains as long as you are using the engine/trans to give you the speeds you need. By manually downshifting the engine can easily handle whatever hills you encounter, but not at the speeds you might want to travel at. When you start down, go slow, and keep the engine speed in the 2000 to 2200 rpm range. If you repeatedly have to use your service brakes to keep engine speed there you are in too high a gear. Slow down further and downshift and watch it carefully. Again if engine speed starts up or the trans shifts to a higher gear you need to go to even a lower gear. By constantly playing the trans and your engine speed, you can get to the point where the engine is maintaining a set rpm speed and you will not have to touch the gas or brakes. Of course when the slope changes, you need to adjust. It's a continuing process.

FIRE UP · 10-06-2015, 12:22 PM

Quote:

Originally Posted by steined

I've been tracking down why my PACbrake isn't engaging for about two weeks now. I have one or two more leads (no pun intended) to check, but am about to set out on our first trip into some mountains.

It will also be my first trip towing a car for a long distance.

I am going from Northern Ohio to Outer Banks NC. It is suggested I go 76 to 70 around DC to 95 the on south.

Is this something that can be done safely without an exhaust brake? If I can't figure it out before the trip, I'm wondering if I should leave the TOAD behind.

I do have an RVi2 brake installed in the TOAD, however those brakes can overheat just as much as the MH brakes I'm sure.

Will engine braking be enough should I not be able to figure it out?

Thanks!

Steined,
GET IT FIXED! At whatever cost, time frame or constraints, GET IT FIXED! I don't mean to be chastising here to you, just really emphasizing the importance of that secondary braking mechanism. They are invaluable in just about every mountain/long grade/steep decent operation. You already know that those service brakes can heat up rather rapidly if over used in certain conditions. Why chance it?

As for leaving the toad behind. Well, that's certainly up to you. I wouldn't drive our coach an inch without a toad. The main reason is, we've been stranded, way more than once. I will NEVER put me or the wife in that predicament again. A motor home, and it's drive train, is made up of a zillion parts. Any one of which can fail at any given time, and leave you stranded, in the middle of nowhere. Of, even in a county/city/rural environment. YOU'RE STILL STRANDED!

And, calling road side service may or may not provide somewhat prudent and immediate service. Many times it's hours before they arrive. Even if they do arrive, YOU'RE STILL STANDED.

Anyway, If I were you, I'd enlist any and all mechanically inclined friends, co-workers (if you still work), a local mechanic, ANYONE who might be able to lend a hand in locating and repairing that Pac/brake.

As for the reason they quit, there could be many. You do know the throttle pedal MUST be completely off, before they'll work don't you? And, in many cases, the cruise control must also be OFF, but not in all cases or motor homes, (mine for instance). I'm assuming there's a fuse or circuit breaker for that PAC brake too but, not sure. And, as far as I know, they won't work below a certain mph so, if you're trying to test it or, trouble shoot it, make sure you're above whatever mph that's required for it to operate. Good luck and, if you would, please report back when you've found the cause so that others may learn.
Scott

steined · 10-06-2015, 12:34 PM

Quote:

Originally Posted by FIRE UP

Steined,
GET IT FIXED! At whatever cost, time frame or constraints, GET IT FIXED! I don't mean to be chastising here to you, just really emphasizing the importance of that secondary braking mechanism. They are invaluable in just about every mountain/long grade/steep decent operation. You already know that those service brakes can heat up rather rapidly if over used in certain conditions. Why chance it?

As for leaving the toad behind. Well, that's certainly up to you. I wouldn't drive our coach an inch without a toad. The main reason is, we've been stranded, way more than once. I will NEVER put me or the wife in that predicament again. A motor home, and it's drive train, is made up of a zillion parts. Any one of which can fail at any given time, and leave you stranded, in the middle of nowhere. Of, even in a county/city/rural environment. YOU'RE STILL STRANDED!

And, calling road side service may or may not provide somewhat prudent and immediate service. Many times it's hours before they arrive. Even if they do arrive, YOU'RE STILL STANDED.

Anyway, If I were you, I'd enlist any and all mechanically inclined friends, co-workers (if you still work), a local mechanic, ANYONE who might be able to lend a hand in locating and repairing that Pac/brake.

As for the reason they quit, there could be many. You do know the throttle pedal MUST be completely off, before they'll work don't you? And, in many cases, the cruise control must also be OFF, but not in all cases or motor homes, (mine for instance). I'm assuming there's a fuse or circuit breaker for that PAC brake too but, not sure. And, as far as I know, they won't work below a certain mph so, if you're trying to test it or, trouble shoot it, make sure you're above whatever mph that's required for it to operate. Good luck and, if you would, please report back when you've found the cause so that others may learn.
Scott

I'm trying to fix it. I can actuate the solenoid and flapper itself by applying 12v to the air solenoid, however I am 99% sure it is NOT working while driving.

Symptoms: My Transmission doesn't downshift when depressing the foot switch, however I can hear some clacking of relays when I step on it above say 5-10MPH from the drivers side console. Upon investigation I see it is likely the Allison VIM, however I am unsure if the clacking or clicking is typical or not. It is a repeated click click click while I have the foot switch depressed.

I am going to try to find, what I assume has to exist, a relay near the air solenoid, and see if it is wired up ok. Of course I won't be able to test it with the coach in park or really at all, but hopefully I find a faulty ground or corroded terminal or something there. If not I may just disconnect the solenoid from the existing wiring and wire up a heavy duty 12V momentary switch or a relay setup to the pac brake for this trip. We'll see.

I wish I knew of a reputable shop around here! Its times like this where I wish I had a Freightliner chassis or something to take to a freightliner service center.

Thanks!

**Lt Dan** · 10-06-2015, 02:45 PM

Quote:

Originally Posted by steined

I do have an RVi2 brake installed in the TOAD, however those brakes can overheat just as much as the MH brakes I'm sure.

Will engine braking be enough should I not be able to figure it out?

Thanks!

Don't worry about your RVI2 brake. It normally does not engage when you are downshifting, only when you apply the motorhome brakes to make a stop. The sensitivity is adjustable, but on mine even on high sensitivity It takes a medium firm brake application before the toad brake activates. Unlike surge brakes, it does not apply just because you are going downhill in a lower gear. Just watch the monitor if you are concerned and if it's braking too much, go up to medium sensitivity.

BLK-9 · 10-06-2015, 05:27 PM

I agree with FIRE UP - 76S from OHIO has lots of construction ongoing and some of those hills are fairly steep - especially going through the tunnel. Be safe.

steined · 10-07-2015, 03:29 PM

Thanks everyone, your words of "encoragement'/Admonishing? It Pushed me to track down the issue.

I had just called 2 diesel shops who couldn't get me in and I decided to call Monaco Tech support. They mentioned that the foot switches were" crap" and to try to use another switch. That solved the problem. The switch was reading high resistance and not giving enough voltage to trigger the relay, which was clacking open and closed, when depressing the old switch.

If I'm ever in the market for a new mh, Monaco gets my business, the fact that they helped me out as 3rd owner of a 15yr old coach says a lot!

Gary RVRoamer · 10-07-2015, 03:32 PM

Downshifting doesn't have much effect on a diesel without and engine or an exhaust brake. Little or no back-pressure in the engine (it is designed to free-wheel when coasting).

That said, drive carefully and keep the speed way down at the top of a grade, to minimize braking needs on the way down. Start out slow and keep it that way. Believe it or not, folks drove big trucks down hills long before there were Jake brakes or PAC brakes. It just requires more driver skill.

Here is one article that may be helpful:
Mountain Driving Without Engine Brake | TruckingTruth Forum

Nana25K · 10-07-2015, 05:00 PM

Quote:

Originally Posted by steined

Thanks everyone, your words of "encoragement'/Admonishing? It Pushed me to track down the issue.

I had just called 2 diesel shops who couldn't get me in and I decided to call Monaco Tech support. They mentioned that the foot switches were" crap" and to try to use another switch. That solved the problem. The switch was reading high resistance and not giving enough voltage to trigger the relay, which was clacking open and closed, when depressing the old switch.

If I'm ever in the market for a new mh, Monaco gets my business, the fact that they helped me out as 3rd owner of a 15yr old coach says a lot!

Can you expound on what you did?? Did you disconnect the foot switch and put in a hand switch???? Ours was mounted up on the angled floor and was a real pain for me to activate. My brother the trucker moved it down into the floor to the left and slightly forward of the seat. I can now just stomp on it with my heal and its engages great

steined · 10-07-2015, 07:03 PM

Quote:

Originally Posted by Nana25K

Can you expound on what you did?? Did you disconnect the foot switch and put in a hand switch???? Ours was mounted up on the angled floor and was a real pain for me to activate. My brother the trucker moved it down into the floor to the left and slightly forward of the seat. I can now just stomp on it with my heal and its engages great

Yep. I just removed the foot pedal and put in a 15A switch in its place. It's not mounted as this is a temporary solution until I get a replacement switch. My foot switch was on the angled piece as well as on top of a block of wood. No issues engaging it, but I may go to a momentary foot switch and spst dash switch after I make the trip and see how much I'd have to have my foot on that switch.

stuhly · 10-07-2015, 08:19 PM

It's not rocket science people. Without a jake brake or exhaust brake you simply decend the hill in the same gear you would climb it in. Jesus, we drove trucks for years with neither.

Rider99 · 12-04-2015, 09:03 PM

There is no better engine retarder than an engine or exhaust brake. If you climb a hill in 4th does not equate to descending in 4th. You either apply the brakes or use a retarder. I was over come with joy the first time I descended the Calif grape vine using a Jake Brake. No more glowing red smoking brakes. Not to mention decending out of the eastern Sierras with 16,000# of horse trailer behind a Dodge or Ford with an exhaust brake and only tapping the brakes a few times as opposed to without and riding them all the way and excited to reach the bottom with some brakes left. Using low gears with a diesel is not a substitute.

timeforus · 12-13-2015, 07:03 AM

Not sure how long you've owned your rig? A few months after I purchased my MH, while getting ready to winterize I attempted to lubricate my PACBRAKE per manufactures recommendations. The movable arm won't move. After numerous attempts to break it free with PB BLASTER and muscle power, it won't budge. Brought to the shop and had it replaced and WOW what a difference. Held the coach back on 8% grades with no problem. Glad I replaced the PAC BRAKE really safes the brakes.