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Ultrapower Allison 1000 Grade Brake (UAGB) Installation 101

Posted 05-15-2011 at 12:18 PM by DriVer
Updated 07-23-2011 at 07:33 AM by DriVer

I wrote this piece in 2009 however I wanted to place a copy here since it's falling deep in the threads in it's original location. I hope it'll provide some value to you if you own a 2001 to 2004 Workhorse with an Allison transmission.

Ultrapower Allison 1000 Grade Brake (UAGB) Installation 101

A couple of days ago I was interrupted from my daily activity, posting here, as the door bell sounded. Roxy took off across the house barking as loudly and repetitively as possible at the person that had the Gaul to make that type of noise in her environment. You would have thought that someone stole her favorite toy but that was not the case. As I approached the front of the house I saw that ol’ familiar Workhorse powered big brown truck sitting by the curb and when I opened the door I was greeted by a square box which was placed off to the side and under our front porch mat.

Original Allison TCM with the air dam fabric removed. The ECM is underneath.

Completing the jumping up and down phase after having received the package, I scurried away into the “inner sanctum” to gently open the box as if disarming a bomb or something and once opened there it was. I pulled out from the box 3 items, silver painted TCM, an unpackaged wiring harness and a zip lock type plastic bag with a wire loop and a short length of plastic loom. Of course instructions but we’ll get to those later.

Facing & marked; Gray on the L (C1- CLR), Red on the R (C2-Red) 32 Way F Micro-Pack W connectors.

The instructions started out with “Greetings”! At this point I’m thinking, “Hey they got the wrong guy” (Kidding!) however the document started out, “Well here it is! This will be the first“in the field” installation that has been done. I think that statement alone took me a few moments to recover from the initial shock, but I then remembered to breathe again and continued reading. So everything I’m looking at is brand new technology with the accompanying documentation which was in its initial release. I’m thinking man oh man I’m in it up to my ears BUT I have a lot of confidence in my ability to make stuff happen.

Replacement TCM, UAGB Harness, Wireloom and Resistor (in bag upper right).

Just to give you a brief overview of what’s involved here’s the “Cliff Notes” summary of what was about to happen. The TCM (transmission control module) needs to be re-flashed with new ROM so that it knows that grade brake circuitry is present. The connectors, Gray & Red that connect to the TCM need to be re-pinned which means you have to open up the connector – pull out some wire connections and move them to new locations and add new wires. Completing the project, a wiring harness consisting of relays, power points, ground connections, T-taps, butt splice connectors and a Grade Brake switch need to be installed and integrated with the vehicle’s systems.

Quality Control Inspection performed by: Miss Roxy "Da nose knows!"

Can you believe this??? Step number one … locate the TCM mounted on top of the radiator. Now if you are at all challenged by that statement … stop here. J

Continuing, the TCM needs to be removed one way or another for reprogramming on the bench by Brazel’s RV Performance. The TCM is removed from outside the RV off of a short ladder through your hood opening. A 10mm socket is required for 3 sheet metal screws. In order to make this job a lot easier, remove the screws that are holding the air dam fabric off of the firewall and lay it down in front of the radiator. You may also need to cut some tie wraps. I had 3 screws & fender washers that held the top of the fabric.

Looking through the forest of wires I found daylight, bright circle. I drilled a second hole adjacent for the blue wire.

I choose to drill a 3/16” hole through the firewall to run the blue wire from the UAGB harness. A piece of ¼” wire loom is provided to cover the wire inside the engine compartment. I could have drilled a much smaller hole however I thought it best to give the wire a little wiggle room. Once drilled, you have to make sure to de-burr the hole. The clue for me as to location for the hole was when I rolled up my dash; I saw daylight from one of the screws I removed that were holding the fabric. I positioned the drill 2 inches to the left, at the same height and drilled into the coach and the hole came out in the perfect position. Your individual coach needs may differ.

Blue wire from the harness comes into engine room. This wire will run to the Gray connector.

Going inside the RV I opened up the doghouse about a foot from the fire wall and left it in place on the floor. There are 2 connectors that go into the TCM a gray one and a red one. The connectors need to be disengaged from the case and pulled off. The connectors themselves need to be opened up. There’s a clear cover over the gray plug’s pins that needs to be removed. There’s a red tab which needs to be slid to the rear and dislodged from its slide on the clamshell. The clamshell’s sides need to be forced open using a small screw driver. Once the clamshell is open you have to locate the individual wires that need to be worked with. The wire is unlocked from its retainer and then with gentle pressure pushed from front to rear while guiding the wire from the rear with a slight pull. This wire needs to be moved over to the neighboring position and a new blue wire from the harness needs to be plugged into the connector to take its place.

Close up of C1 Gray connector. Note the lock (red) slides to the back and is to be removed.

The red connector needs to be disassembled in the same manner. It has a red sleeve around the pin connections. Once the clamshell is open, one wire needs to be removed, taped with “33” ET and secured back on the harness and a “U” shaped jumper wire actually a resistor is inserted in the connector. Once the wire is pushed into place one needs to make sure that all the pins extend out in front of the connector to the same distance. You may need to adjust the positions slightly. Close the clamshell – it’ll click somewhat if you catch it just right, restore the red locking tab to the top of the connector, and slide the red pin cover over the pins. Look for an index mark on the plastic pin cover. It looks like a small key. On both connectors the tab goes up. (Same process for the gray connector)

Once both clamshells have been restored, it's time to reinstall the TCM. I left the blue wire loose for the moment since I needed to fit the provided wireloom.

Observing the blue wire from the doghouse opening, I took the wireloom, opened it and worked it onto the wire and pushed the loom up from inside the coach. It went all the way up to the firewall entry point. I went around to the front to check where the loom stopped and it was right on the money. Going back inside, I stretched the loom out and approximated a distance, cut and laid the rest of the wire loom on the wire.

Clam shell connector is pried open revealing the conductors. Note the lock (red) removed.

Continuing I placed a piece of ET about every 8 or so inches to keep the loom closed. I secured and tie wrapped the wireloom just behind the clamshell on the main wire bundle. Going back around the front of the motorhome, I tied off the wireloom onto the TCM frame and checked to see if it was clear of any other equipment. Completed, the wire loom is going to lie under and behind the air dam.

The next step is to restore the air dam fabric. In my case, the top of the fabric covers the hole I drilled in the firewall. I secured the fabric using the old screws however I fitted new fender washers. Completed, secure the hood opening.

OK - Next step push the doghouse back in place and secure it down. I have a 5/16” Allen type bolt head that I twist clockwise on the back of the doghouse. At this point you’re about 50% complete.

The main wire harness should be laying on your dash or close by. I continued not so much in the same manner as detailed in the instructions but approached my end game from the blue wire toward the final location of the Grade Brake switch. Next up I made the ground connection, there’s a ring connector provided on the harness.

Pin end of connector. The flat tabs (white) on the top of the sockets hold the pins. Lift the tab and push the pin out.

After that I tackled the brake switch attachment point. This connection used a T-tap that featured a female spade attachment point. Find the blue wire on the brake switch, for me it was on the right side looking from the top down. I was able to work through the top opening and the bottom to hold and secure the T-tap. I broke the one that came with the kit so I had to go to my NAPA and pick up another box full. What a pain those things are.

Once the T-tap was in place all that is needed is to plug in the insulated male spade into the T-tap. I also use a high intensity mini-mag light to check all the connections. Once the T-tap is secured you should see a little tab locked in place. Make sure this connection is correct because the GB does not function without it. To confirm the connection use a test light and probe the metal connector inside the T-tap and step on the brake pedal. The test lamp should light up.

Completing the wire modifications to the connector, note the orientation of the pins. All even and equal length shown.

Note to self buy a smaller mini-mag with a duck bill holder. That would have worked a lot better.

Continuing, it’s now time to attach the power wires to the coach’s fuse panel. 2 specified fuse locations are required in the instructions. A flat blade type connector with a rectangular opening provides a means to attach each wire to the leg of the fuse. Once clipped on, the fuses can be restored into their sockets. What is important here is that the cold side needs to be identified in both cases using an automotive test lamp. Turning the key “ON”, test both wires for power. One feeds the relays I expect and the other feeds a dim light inside the switch (nice). The light in the switch does not toggle on and off.

This is the C2 connector (Red). Note the resistor installed. "Hand" supplied by: Depchief

Now comes the fun part – can I see a show of hands as to how many folks want to cut a rectangular 7/8” by 1.5” hole in their dashboard? I approached this task very carefully and considered a number of locations however in the end – I had to blast!

The first thing that needs to be done here is to disconnect the GB switch from the modular connector on the harness. A small screw driver is used to make a purchase on the sides and while working both sides a little bit at a time, the modular connector eventually comes off. You cannot pull the thing off so don’t try.

Completed and closed shells with pin collars restored. Note C1 blue wire. C2 wire taped back on harness.

I used the enclosed template to transfer the lines onto a piece of Avery label. Once I applied it to the dash I rolled the dash down and used a level to check the template lines. Close enough for government work I said and then I began the process of cutting a hole. Now some techs will use a saber saw but I chose to drill four 3/16” holes inside the rectangle corners and then I used about a 1/8” inch drill bit and drilled about 25 or more holes around the diameter of the rectangle. Once all the holes were in place, I got my sheetrock knife, changed the blade and began cutting in between the circles. I do both verticals first, the bottom and then the top. I broke out the piece and what a horrible looking mess.

Ready to begin installing UAGB harness, coiled on dash above TPMS. Prop rod courtesy of Sherwin Williams. Note doghouse position.

I fit the GB switch to the hole and checked for clearances – none “perfect” I said. So now being careful from this point forward and checking frequently I used my knife to whittle away at the plastic a sliver at a time. Once the body of the switch fit the hole I put it down and reached around for the modular connector and pushed it through the opening. There is a round post on the back of the switch so you can’t mess this up. I pushed the switch into the modular connector being careful not to apply any pressure on the face of the switch as to damage the switch mechanism. Once the mod connector was all the way on the switch I pushed the switch into the face of the dash and it fit perfectly. The grip on the switch is a stepped type of an affair that once pushed into its recess adapts to almost any thickness of material. I toggled the switch just for fun and it felt solid. Nice! and .... Whew!

Replacement Allison TCM installed. C1 & C2 connectors restored to their original positions.

The next task on the list although not complicated was one of the most invasive which requires that the OD switch wires be cut. Man talk about cut once and once cut, it's cut. So there is a gray wire that needs to be cut “in the middle” and it’s only exposed out of its harness by about 4 inches. I stripped the insulation off the wire about 3/4s of an inch twisted the strands together and folded the wire back on itself so that it would make for a greater diameter conductor in the provided blue butt splice connector. You have to do 2 connections and the polarity is important. The last connection to the OD switch is made to the purple wire using again a T-tap connector like was used on the brake light switch. I secured the OD wires that go to the switch using a tie wrap on a hard point under the dash to finish the installation of the harness.

Wire loom fitted over blue wire to the C1 connector. ET is applied every 8 inches and tied to fixed hard points clear of the fabric air dam.

I lowered the dash pod down observing that everything was clear. I turned the ignition on and fired up the engine! So far so good. We have ignition start and no DTCs. I reached up and toggled the OD switch On & Off and the lamp on the IP responded. I scanned for codes using my SGII and none were found. I turned the headlights on and the UAGB switch is illuminated through the lettering "Grade Brake" but very dimly and I expect it will not be obtrusive at night. I shut the engine down and took a big sigh of relief and smiled!

Fabric air dam restored. Note 3 attachment positions with new fender washers.

At this point the installation and initial test was complete and it was time for me to go and have a seat on the couch!

Technology Demonstration - Test Drive:

Next day, Beau came over, “Depchief” (I actually drafted him to ride right seat for the test drive) and we fired up the engine and went for a ride. The TCM at this point was totally blank since it’s adaptive and it needs to relearn how you drive. I came up to my first left hand turn and slowed down and the tranny clunked down into 1st. Beau and I looked at each other and said, “Oh?” but we soldiered on. Running up the road, I happened to look over my shoulder and saw a lot of loose gear on the counters. "Not my job", but I had pull over and stop, go clear the decks and jump back in the seat. Off again down the road in a WOT profile and accelerated quickly having no toad on my six. So far the shift patterns upward were nice and smooth, no problems, but I didn’t get up to 50+ MPH yet.

The UAGB harness ground attached. It’s a serrated ring connector.

Once I turned onto a 55 MPH state road I accelerated, shifting normally and smoothly all the way to 4th gear. Once I hit 4th gear at about 45MPH, I backed off of the throttle a bit and continued accelerating upward toward 50 MPH. Once I hit close to 51 MPH the tranny up shifted into 5th gear (OD). Beau and I commented; “That’s workin!” and we kept on trucking. Having now easily surpassed 55 MPH, I stepped on the brake and the tranny down shifted to 4th as it was supposed to do. Point #2 verified.

UAGB harness requires 2 power point attachments to the coach panel.

We continued down the highway and I toggled the OD switch on and off no problems and I "select shifted" down and then up through the gears with no problems as well.

A T-connection is required to the blue wire on the brake light switch.

Now in case you don’t know where we live … there ain’t no hills on the beach so I wasn’t able to test the “grade brake” feature as of right now but that will come next month on the way up to Virginia. I am confident that with the core technologies demonstrated that there shouldn’t be any reason why the UAGB won’t perform as designed and we’re waiting to get that final part of the test in the books. I expect that it will work just fine.

I used an Avery label, penciled in the template (fabricated). I leveled the label. 4 pilot holes were drilled in corners, smaller holes drilled vertically and horizontally. Cut with razor knife and trimmed out.

While we were on the road we came to several more slow turns and stops and there wasn’t any downshift clunk observed. The TCM had already began to learn new tricks. Anybody thinking about retiring this “Ol’ Paint” better come again because at 81,900 miles this thing just keeps getting better every day!

OD Gray wire cut and crimped. Purple wire is T crimped. I tie wrapped the UAGB harness to fixed points under dash.

The Ultrapower “Allison” 1000 Grade Brake is only intended for W Series with 5 speed transmissions. At this time, the majority of the owners of 5 speed transmission are out of warranty. So, I don’t expect that this installation is going to void any warranty.

Ultrapower Grade Brake Switch mounted. Text is very softly illuminated.

This aftermarket product brings you up on par with 2005 and better chassis technology that has an factory OE grade brake. By “your” request, the up-shift speed was reduced by 5 MPH to about 51. For those owners that have often complained about having to “exceed” 55 MPH to get their tranny to upshift in a 55 MPH speed zone, this feature should be of benefit. Those driver’s will I expect welcome the new programming change. I also hope that it may incrementally save fuel in the long run since you’re getting into OD a bit quicker.

Project finished, showing an excellent position for the switch and we’re ready to hit the road. Once turned “on” the GB switch does not need to be turned off. Note the "SSC" horn button.

I’ve enjoyed doing this install and bringing you this project as an product installation and photo shoot. I hope that you have enjoyed it and I am looking forward to answering questions.

Well that’s all I have for now … on to my next project. J

For more information call:

Steve or Jon Brazel
Brazel’s RV Performance Center

Mike Bronzini
Redlands Truck & RV Center
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Total Comments 7


  1. Old Comment
    Sky_Boss's Avatar
    WOW...That seems to have been a big project but it appears ya done good! My question is how did you get the dash to pop up like that? I'm thinking I may need that bit of knowledge for a radio project.
    Posted 04-26-2012 at 11:04 PM by Sky_Boss Sky_Boss is offline
  2. Old Comment
    DriVer's Avatar
    Originally Posted by athuddriver View Comment
    WOW...That seems to have been a big project but it appears ya done good! My question is how did you get the dash to pop up like that? I'm thinking I may need that bit of knowledge for a radio project.
    I didn't think that folks were still reading this piece but thanks for the review.

    In the piece I wrote that I was the first person in the field to install the kit and that it went very well.

    In regard to the dash, certain models of Winnebago motorhomes had their dash pods on hinges. Lifting the dash with this fitted is a breeze. In later production years, Winnebago only provided fixed dash pods and no longer provided easy access to the under dash wires and components.

    I have found that most RV manufacturers have fixed dash pods so I feel that my rig "type" is the exception rather than the norm.
    Posted 04-27-2012 at 07:37 AM by DriVer DriVer is offline
  3. Old Comment
    You did a great job on this description. If I was in better physical shape I would feel very comfortable following your lead and doing it. Will probably see Brazel's in Quartzsite this winter
    Posted 10-06-2012 at 07:54 PM by rvrovers rvrovers is offline
  4. Old Comment
    CJ7365's Avatar
    Driver, I just installed the grade brake on my W22, your pictures and attention to detail on your install were great.

    Although now, Jon has upgraded the kit, you do not have to splice the OD wires, the GB harness now comes with a female and male OEM plugs, so now you just unplug the OD connector and insert the GB connectors, a lot easier process.

    Hats off to the guys at Brazels, to upgrade this connection, its a lot easier now.

    So I only had to install 1 T tap, and yes those things are a pain.

    Everything works fine, I really like the overdrive engaging at 48mph instead of 55mph

    I live in the desert so no big hill to test the GB on yet, but heading out west this summer.

    Thanks again for posting this

    Posted 06-04-2016 at 10:04 PM by CJ7365 CJ7365 is offline
  5. Old Comment
    DriVer's Avatar
    Originally Posted by CJ7365 View Comment
    Driver, I just installed the grade brake on my W22, your pictures and attention to detail on your install were great. Thanks again for posting this
    Rob, It's good to know that folks like yourself are still reading my stuff! You are welcome!
    Posted 06-04-2016 at 10:42 PM by DriVer DriVer is offline
  6. Old Comment
    Hi DriVer, thanks for this post. I'll be getting a kit from Brazel later this year to install before we take off on any long trips later this year and next.

    Posted 07-25-2016 at 08:50 PM by YO_ YO_ is offline
  7. Old Comment
    DriVer's Avatar
    Originally Posted by YO_ View Comment
    Hi DriVer, thanks for this post. I'll be getting a kit from Brazel later this year to install before we take off on any long trips later this year and next.
    I was the guinea pig for the early model however I have come to understand that you no longer have to manually pin-out the TCM connectors. URVP now provides plug-in modular connectors to improve the reliability of the connections and make the integration process a breeze.
    Posted 07-26-2016 at 08:45 AM by DriVer DriVer is offline
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