Thor Miramar - Brake warning lights come on

[kdanielson]

I just bought a 2016 Thor Miramar 35.2 in Davis, CA. While driving it home to Washington State the 'parking brake and brake reserve' warning lights came on. This only happened once while coming down a 4% grade. I pulled over to the side of the road when I could, tuned off the engine, waited a few minutes before turning it back on, and the error was cleared. We continued on without it reoccurring.

Here's what lead up to the warning light error:

Coming down a lengthy downhill 4% grade
Engine downshifted twice
Tack @ 4 grand
Tapped brakes several times to provide additional slowing
Parking Brake and Brake Reserve warning lights came on
Everything seemed to continue to work normally

Stop and cycled engine - problem didn't reoccur.

I'm wondering if anyone else has seen this?

Kim

[brianh442]

Could be a problem with your brake system, according to the Ford owners manual, they recommend having it looked at by a technician. Not sure where in WA you are going, but if you are in the Seattle Tacoma area, Scarff Ford Truck Center in Auburn is a great place to have it looked at.

I've been going there for a couple of years, they always take good care of my rig.

[kdanielson]

I agree with your assessment and in fact, Ford (Horizon Ford - Tukwila) had my rig for a week and couldn't find anything wrong. I suspect they didn't have any experience with this engine - Triton 6.8L and the HydroBoost braking system.

I'll be taking it into Riverside Ford in Sumner next time.

[EA37TS]

Originally Posted by kdanielson

I agree with your assessment and in fact, Ford (Horizon Ford - Tukwila) had my rig for a week and couldn't find anything wrong. I suspect they didn't have any experience with this engine - Triton 6.8L and the HydroBoost braking system.

I'll be taking it into Riverside Ford in Sumner next time.

First, welcome to the forum.

Have your dealer look at Ford TSB 16-0042. I read on other sites (Ford Truck Forum) that there may be a mistiming of the Brake ON/Brake Off switch and the solution is to do a re-flash of the ECM. If that is the case the Ford dealer should handle it under warranty.

[brianh442]

Originally Posted by kdanielson

I agree with your assessment and in fact, Ford (Horizon Ford - Tukwila) had my rig for a week and couldn't find anything wrong. I suspect they didn't have any experience with this engine - Triton 6.8L and the HydroBoost braking system.

I'll be taking it into Riverside Ford in Sumner next time.

I went to Sumner once, they don't like bigger RV's at their facility, their shop space is limited. It was at their recommendation I went to Scarff in Auburn. Scarff has way more room for bigger RV's.

How are you liking the 35.2 so far??

[kdanielson]

Thanks for the Tech Tip Dave - I'll definitely bring this up. I'll update this thread with the outcome - once I get one...

[kdanielson]

Thanks for the info Brian...

I'll keep that in mind.

[kdanielson]

...and we love our Miramar 35.2 so far... it has a great floorplan...the opposing slides really opens up the living space.

[schreinertms]

Does anyone know what the "brake reserve" is on a Ford F53 chassis? Does it have something to do with the Hydroboost system?

[EA37TS]

Originally Posted by schreinertms

Does anyone know what the "brake reserve" is on a Ford F53 chassis? Does it have something to do with the Hydroboost system?

The way I understand it the Hydroboost system will build and store reserve pressure that assists with braking. This reserve pressure is stored in a hydroboost accumulator.

[brianh442]

Originally Posted by kdanielson

...and we love our Miramar 35.2 so far... it has a great floorplan...the opposing slides really opens up the living space.

That's great, that model looks nice! We are 8 months into our replacement coach, which is a 33.5. I must say, our experience thus far is 100% better! The quality and craftsmanship is much better on the 33.5.

So far, I've only had 3 or 4 minor issues and the dealer was able to repair them in short order, (less than 5 days). 8 months into our last coach (2014-34.2) it had of list of 30+ defects and had been in the shop over 3 months at that point.

Safe travels!!

[Jbird_in_SC]

Hi everyone - I am new to the forum and found everyone's help terrific. Thank you. I am having the similar issue (brake system and brake reserve system lights constant on) on my 2017 Thor Challenger 37TB. Looks like I'll need to bring it into Ford truck dealership and direct the service tech to TSB16-0042.

[kdanielson]

That tuned out to be the solution to my problem...

Good luck!

[Jbird_in_SC]

I brought our RV into a nearby Ford truck service center and unfortunately the previous TSB16-0042 does not work for 2017 Thor / 2016 Ford F53 chassis. Or my issue is not a simple fix. More to come...

Thanks,
Jay

[Jbird_in_SC]

First, I am grateful for a dedicated and detailed Ford technician who continued to troubleshoot until he found the issue. Granted, we missed our short trip this past weekend, but the Ford Dealership and technician are the reasons we'll be able to get on the road for an upcoming long weekend. Here is a summary recapping the chain of events to resolve:

- Technician confirmed issue (brake system and brake reserve system lights constant on).
- Checked codes and had several c148a, c1491, u0100 and u0155
- Checked "oasis" to TSBs and SSMs, but none found.
- Performed update for the PCM, cleared codes and reran for tests for ABS and no codes came back, network test pass.
- Test drive, lights back on within a mile. Codes above returned.
- Technician noticed with the "koeo" (test?) when brake pedal pressed, the hydro-max systems was not working like it should.
- Used a brake pedal depressor while under the hood to check fuses and wiring.
- When touched hydro-max relay the motor turned on, when released it turned off.
- Begin touching wires and when yellow wire was wiggled, the motor ran. When yellow wire pulled, it came out of connector 1201.
- Inspected at end of wire and it was not properly installed from factory.
- Repaired Yellow wire 275 at c1201.
- Hydro-max now runs with "Koeo" with brake pedal pressed.
- Cleared codes and test drove for 30+ miles. No codes or lights on dash.

I drove about 15 miles home and no issues. I do not anticipate further issues, but if we encounter any I'll update this post.

Again, very thankful for a great Ford truck technician and a Ford Dealership that values exceeding customer expectations on getting a customer back on the road.

Thanks,
Jay

[JamieGeek]

KOEO test: Key On Engine Off, KOER Key On Engine Running

[ctpres]

Just had same problem with our 37KT during long hard mtn decent. I found couple of reports that problem showed up during during hard/sharp turns. And we did have that several times on switchbacks. Have about 500 miles on engine since and no problem. TSB on my list - just need to be sure I remove 5 Star Tune before service.

[ctpres]

Just got 5Star response to my question re need for 5Star involvement BEFORE tune reinstalled after getting Ford TSB16-0042 installed.
"most likely will need new tunes for new strategy"
Kinda short answer, guess it means they don't know yet.
If you have 5Star tune - don't forget to remove it BEFORE taking your F53 to Ford.

[schreinertms]

The May 2016 issue of Motorhome magazine has a good article on engine retuning.