Flat Towing, unexpected brake lockup.

[grtharris]

I have heard of this happening to a couple of user and I have had it happen to me a couple of times. Just a couple of weeks ago whilst I was in Colorado a fellow Bronco puller called me asking if I had it happen to me. Up until that time it had only happen one time. Well on the way out of Colorado coming into Monte Vista I was slowing down from 55 to 65 with some braking and it felt like had dropped an anchor. My aux brake system was originally designed to be used with active brake boost so I normal do not get a lot of braking from the Bronco so it was quite obvious the boost went active. A little way down the road I was stopping at a red light and got a little chirp from the bronco tires. By the time I was able to pull over, I checked everything and all looked normal and no miles had been added to the odometer. Didn't happen again the rest of the way home.

Just wondering how many others have had this happen and It anyone was able to make it happen.

Sponsored

 

[BigMeatsBronco]

tons of threads on this subject. YES others have had the SAME issue.

 

[SuperDave150]

Yes, and Blue Ox recommends pulling the fuses to the brake booster to prevent this.

 

[Bsenecal]

Yes, and Blue Ox recommends pulling the fuses to the brake booster to prevent this.

That’s for the 2.7 V-6 correct? Not the 2.3.
Brian

 

[Beach_Bum]

That’s for the 2.7 V-6 correct? Not the 2.3.
Brian

Yes. MY'24 and earlier 2.3L have vacuum assist brakes. For MY'25, the 2.3L will be getting electronic brake boost.

 

[Bsenecal]

Yes. MY'24 and earlier 2.3L have vacuum assist brakes. For MY'25, the 2.3L will be getting electronic brake boost.

Interesting, that’s why we changed our engine after we initially ordered a 2.7, I was reading all the issues people were having flat towing and wasn’t going to get something that I had to pull fuses each time.
Glad we bought a 22.
Brian

 

[SuperDave150]

I have heard of this happening to a couple of user and I have had it happen to me a couple of times. Just a couple of weeks ago whilst I was in Colorado a fellow Bronco puller called me asking if I had it happen to me. Up until that time it had only happen one time. Well on the way out of Colorado coming into Monte Vista I was slowing down from 55 to 65 with some braking and it felt like had dropped an anchor. My aux brake system was originally designed to be used with active brake boost so I normal do not get a lot of braking from the Bronco so it was quite obvious the boost went active. A little way down the road I was stopping at a red light and got a little chirp from the bronco tires. By the time I was able to pull over, I checked everything and all looked normal and no miles had been added to the odometer. Didn't happen again the rest of the way home.

Just wondering how many others have had this happen and It anyone was able to make it happen.

Just for clarification, when you say “brake lockup“ do you mean that the tires actually stopped turning at all & said “not another inch without leaving skid marks”, or, that it was unexpected how much of a sudden effect they had in comparison to how little they had done before?

 

[dgorsett]

I have heard of this happening to a couple of user and I have had it happen to me a couple of times. Just a couple of weeks ago whilst I was in Colorado a fellow Bronco puller called me asking if I had it happen to me. Up until that time it had only happen one time. Well on the way out of Colorado coming into Monte Vista I was slowing down from 55 to 65 with some braking and it felt like had dropped an anchor. My aux brake system was originally designed to be used with active brake boost so I normal do not get a lot of braking from the Bronco so it was quite obvious the boost went active. A little way down the road I was stopping at a red light and got a little chirp from the bronco tires. By the time I was able to pull over, I checked everything and all looked normal and no miles had been added to the odometer. Didn't happen again the rest of the way home.

Just wondering how many others have had this happen and It anyone was able to make it happen.

Well Grant if this happened to you it can happen to anybody. I assume you are using the software fix and not pulling a fuse, correct? And some have claimed the parking brake had engaged while towing, but yours was definitely the service brake?

 

[lamokadave]

My situation with my 24 2.7 BL SAS. I'm using the RVI3 aux brake. Before I install it each time, I will pump the brakes several times just to release any braking energy in the system. I started doing that after speaking to the technical guys at rvi describing my problem to them. The EBB Re-Engagement is somewhat random. Typically I can drive and use the brakes for 45 minutes to an hour with no issue and then all the sudden even with light brake pressure, the Bronco Wheels will lock up. There have been occasions however that it happens very shortly after I start flat towing. While at a Ford dealership getting an oil change, I described the condition to the service writer. The tech checked out the vehicle and they said there was a code being thrown by the EBB and they actually ordered a new one and replaced it. That did not improve the situation at all. My workaround has been to select panic stop only mode on the rvi controller that requires a very hard braking force before the rvi will activate the brakes and then the Bronco locks up. The last time I flat towed I followed the fuse pulling procedure and everything worked perfectly doing that. I did that to see if I could eliminate the rvi device as the problem.

 

[beerme1986]

So my story about the wheels locking up while flat towing has been an issue from day one (three years). But let’s just talk about since the update from ford that turns off the power to the ABS and EEB systems as soon as you switch to flat tow was installed. Most times when the brakes lockup it is when I am driving slow like down an off ramp or getting ready to make a left hand turn and hours after the trip started. It requires a full stop before the RV3 will release the brakes. The last time was about an hour after the trip started going down a hill about 45, lightly applied the brakes on the motor home doing 45 mph and the brakes locked up and was able to pull off the road and reset the RV3. I did not check to see if the brake pedal was active or dead. Reset everything and made it home. So the tech folks at RVi tell me that the RV3 will not apply enough pressure to lockup the wheels on the bronco with a dead pedal so if the wheels do lockup, then the pedal has active assist turned on. So I am going to test this out. Will pull the fuses after I put the bronco in tow mode and take a ride behind my motorhome and see if depressing the brake pedal will lock up the wheels. Will post the results late next week.

 

[73Corvetteman]

So my story about the wheels locking up while flat towing has been an issue from day one (three years). But let’s just talk about since the update from ford that turns off the power to the ABS and EEB systems as soon as you switch to flat tow was installed. Most times when the brakes lockup it is when I am driving slow like down an off ramp or getting ready to make a left hand turn and hours after the trip started. It requires a full stop before the RV3 will release the brakes. The last time was about an hour after the trip started going down a hill about 45, lightly applied the brakes on the motor home doing 45 mph and the brakes locked up and was able to pull off the road and reset the RV3. I did not check to see if the brake pedal was active or dead. Reset everything and made it home. So the tech folks at RVi tell me that the RV3 will not apply enough pressure to lockup the wheels on the bronco with a dead pedal so if the wheels do lockup, then the pedal has active assist turned on. So I am going to test this out. Will pull the fuses after I put the bronco in tow mode and take a ride behind my motorhome and see if depressing the brake pedal will lock up the wheels. Will post the results late next week.

Mine started doing it about 2 weeks into 2 month trip. I could never pin point a common factor that causes it to happen. I did note that 2 times when it happened it stopped after running over rumble strips before stop light. Which makes me think bad connection somewhere. I started pulling fuses after the 5th time it did it. Never had it happen ever with fuses pulled.
I pulled over the last time it happened, checked everything, could not find anything wrong. When I started back out it was fine.
I'm going to dealer next week to see if they can figure it out but I am not going to hold my breath...

 

[Tilzbow]

This comment is only based off of my memory, which can be poor at times, but most of the brake locking situations I’ve read about on the forum have had the RVi3 auxiliary brake system installed. Could there be issue with the auxiliary brake rather than the Bronco?

 

[73Corvetteman]

This comment is only based off of my memory, which can be poor at times, but most of the brake locking situations I’ve read about on the forum have had the RVi3 auxiliary brake system installed. Could there be issue with the auxiliary brake rather than the Bronco?

I have an older roadmaster system. Since I started pulling fuses have not had it happen. One time I skipped pulling fuses to see what would happen and the brakes locked again. When I say locked I mean the brakes come on too hard when I hit motorhome brakes. They release when I release motorhome brakes. Sometimes by the time I find a place to pull over they have quit doing it.

 

[beerme1986]

Results from test. The bronco was pulled by the motor home, bronco in flat tow, fuses pulled for entire time and all testing was at 15 MPH and a slight down hill road. So when I was in the driver seat I pushed as hard as I could and I did get one wheel to lockup. But I am pushing a lot harder than the RV3 and the sound I hear in the motor home when the bronco wheels do lock up on a trip sounds like all 4 wheels, not one and it sounds like the anti-lock brake system is active. So next I installed the RV3 got into the passenger seat and controlled the system. Started with the small SUV setting and manually fully applied the RV3 braking system. No lockup and worked well. Next pulled the breakaway switch and the RV3 applied max pressure and no lockup. Next, set the RV3 to the truck setting. Manually fully applied the RV3 braking system. No lockup and worked well. Next pulled the breakaway switch and the RV3 applied max pressure and no lockup.

So what I get out of this test is the SSM 51415 software update has a bug. At some point the bronco brake system is active and when the RV3 applies the brakes that works well with a dead pedal, will lockup the wheels which tells me the bronco brake system is active. So looks like the ball in in Fords court.

Did turn in the complaint to the ford customer relationship center at 866-631-3788. So maybe if everyone that has an issue with the wheels locking up does the same thing, maybe they will address this life safety issue.

 

[73Corvetteman]

Results from test. The bronco was pulled by the motor home, bronco in flat tow, fuses pulled for entire time and all testing was at 15 MPH and a slight down hill road. So when I was in the driver seat I pushed as hard as I could and I did get one wheel to lockup. But I am pushing a lot harder than the RV3 and the sound I hear in the motor home when the bronco wheels do lock up on a trip sounds like all 4 wheels, not one and it sounds like the anti-lock brake system is active. So next I installed the RV3 got into the passenger seat and controlled the system. Started with the small SUV setting and manually fully applied the RV3 braking system. No lockup and worked well. Next pulled the breakaway switch and the RV3 applied max pressure and no lockup. Next, set the RV3 to the truck setting. Manually fully applied the RV3 braking system. No lockup and worked well. Next pulled the breakaway switch and the RV3 applied max pressure and no lockup.

So what I get out of this test is the SSM 51415 software update has a bug. At some point the bronco brake system is active and when the RV3 applies the brakes that works well with a dead pedal, will lockup the wheels which tells me the bronco brake system is active. So looks like the ball in in Fords court.

Did turn in the complaint to the ford customer relationship center at 866-631-3788. So maybe if everyone that has an issue with the wheels locking up does the same thing, maybe they will address this life safety issue.

I took mine to the dealership yesterday. It had multiple codes concerning communication issues in parking brake system. Mechanic was very knowledgeable and told me that this is not an isolated problem. He said an update seems to be causing issues. The vehicle senses movement if key is off and applies parking brake. This is supposed to be overridden when in neutral tow mode but for some reason it activates intermittently. He installed an update but wasn't sure it would help. He wants me to test it out to see what it does. If it's still a problem he is going to open a case with Ford to further investigate the issue.
Being it's impossible to duplicate the issue in the shop I appreciate the difficulties in solving problem. I will work with them to see if we can isolate problem.

Sponsored