Cold weather causes brake failure???
 

The temperature hit 4 below this morning at Lake Tahoe. When I started my '05 FEH, the ABS and brake warning lights came on, along with a message to "check brake system." To make a long story short, apparantly the regenerative braking system was not working. The hybrid power display showed no green arrows flowing to the battery when brakes were applied, although I could stop. I drove about six miles with this condition, then parked in the sun. Three hours later, with the temperature in the mid 20's, I restarted the vehicle. All systems were normal. The power display showed a flow to the battery while braking. Has anyone else had this problem, and what is there about the braking system that could cause a temporary failure of regenerative braking in very cold weather? Thanks for your help.

Re: Cold weather causes brake failure???
 

Zero problems here. Going into second cold season, temperatures have dropped to as low as -40 degrees area.

Re: Cold weather causes brake failure???
 

I should have added that my vehicle was not garaged. It was outdoors all night in sub-zero temps.

Re: Cold weather causes brake failure???
 

Just some thoughts on possible causes of your problem.

I would not surprise me if Ford programmed the FEH not to use regen if the battery temp is below a certain temp. Charging is hard on very cold or very hot batteries. It may be to protect the reliability of the HV battery.

What is odd is the ABS warning light. I can't imagine that being a "normal" response to being parked outside in subzero weather. I would ask the dealer about it. Perhaps the brake system could be flushed to make sure there is no water in the brake lines?

Re: Cold weather causes brake failure???
 

We've had near zero off and on since October, and several weeks of consistently below zero weather here where the car is parked outside for 9 hours during the workday, and there have been no symptoms like that.

I've had one case where the car was very cold and the idle speed seemed to make "surges" to 2800 rpm every 10 seconds or so, and it felt that maybe it was being felt in the brake pedal.....but not much. It went away after about 5 minutes of driving. Other than that, completely normal operation. As expected, when the battery is cold there isn't much in the way of electric assist or charging until it warms up, but no lights and no odd symptoms.

Re: Cold weather causes brake failure???
 

My two cents is that the brakes lost its calibration. This happens when you disconect the 12V battery, or you have a computer glitch. The "check brake system" light would have stayed on till you did a reset by turning off the ignition switch for a few seconds and turning it back on. Since you continued to drive and not reset the system, the brake system remained in the protective mode.

Anytime you get a trouble light, you should try resetting things by a reboot of the computers. In addition, to recalibrate the brakes, leave the eCVT in "Park" and press the brake pedal all the way down till it stops travel. Let off and the computer will calibrate back to the original setting. If you still have a warning light, reboot by turning off the key and restart.

GaryG

Re: Cold weather causes brake failure???
 

I THINK the loss of regeneration is likely very normal at cold temps until the battery warms up. However that doesn't explain the ABS light and the check brake system..... That part might be something to have looked at. But even if they fix something I'll bet you still won't regen when its that cold at the start, I'll bet that is normal and not a symptom of the light and warning... The car will just brake like any other car in those conditions and still be safe.

Re: Cold weather causes brake failure???
 

No garage either :(

Re: Cold weather causes brake failure???
 

I tried that twice-- once shortly after I first started the ignition and again after driving a couple of miles.

The idea from others that charging is limited until the battery warms up makes sense. The ABS light is troubling, but I'm due for a 70k service, so I'll get the brake system flushed and checked.

Thanks to all here for the quick advice.

Re: Cold weather causes brake failure???
 

If the warning did not reset and came back on, your problem continued. You need to take it in ASAP so they can check for stored codes. It's more than a brake calibration or flushing the fluid I bet.

GaryG

Re: Cold weather causes brake failure???
 

According to the US patent granted to Ford the FEH/MMH regenerative braking is disabled (assuming actual patent application) if the OAT hovers around freezing or below. Too much danger of encountering slippery roadbed conditions wherein engine compression braking or regenerative braking on FWD or front torque biased AWD vehicles is potentially unsafe.

Re: Cold weather causes brake failure???
 

I can assert that regen for certain takes place from -20 all the way on up to 75 or so (anything hotter than that, and we consider it unsafe to go outside) provided the battery is warm enough to take it. And it works (and works surprisingly well, I think) in very slick conditions.

We get the condition pretty from time to time that the road surface is very cold and air temps go into the upper 30's or 40. Since there is hard ice on the road, the surface gets wet on top of that, and it is, what we call, "really slick". Slick as in, parked cars without studs slide around the parking lot from wind" slick. :omg:

Even under those conditions (without the recently added studded tires), regen worked and was not particularly squirlley (I don't really know how to spell that). But also below freezing and below zero (when interestingly, it starts to get slicker than when it is, say, 10 degrees), regen works. Except for the temp of the battery, I've never noticed it not working for any period of time.

Re: Cold weather causes brake failure???
 

I drive in "L" quite a bit and I can also say that at 20F or so the regen is still active and it feels fine. They may have a patent and have decided it wasn't useful and not included the work on the FEH.

Re: Cold weather causes brake failure???
 

Hi Tim

It may be a good idea that you read what Willard may be reading. It's not an on and off situation, so I think disabled is not a good term for Willard to use. Maps are used for different situations and temps. An ABS event can disable regen for obvious reasons.


Temperature compensated lift-throttle regenerative braking
The amount of regenerative braking that is applied to the wheels (105) of a vehicle (100) is based on ambient temperature and a lift-throttle event. An ambient temperature sensor (108) monitors the temperature around the vehicle. Based on the temperature, a map is selected (204, 212, 214). If a lift-throttle event occurs, then the map is applied (206, 208). Compression regenerative braking is reduced to zero if an anti-lock braking system event occurs or if the throttle is re-applied, or both (216, 218, 220, 222).

http://www.freepatentsonline.com/658...hlight=5343970

You and Andy are right IMO.

GaryG

Re: Cold weather causes brake failure???
 

Actual regenerative braking (BRAKING!!) can only occur upon a lift-throttle event/circumstance wherein an ordinary vehicle would incur engine compression braking. Remember that when the ICE is producing torque to move the vehicle forward it can simultaneously be used to charge the hybrid battery.

Look at what is going on at the moment throughout the industry with regards to alleviating safety issues with automatic transaxles and engine compression braking on FWD or front torque biased AWD vehicles. Toyota/Lexus, Ford, and VW are all taking a lot of HEAT over what is being referred to as 1-2 second throttle lag and/or downshift hesitation delay in their automatic transaxles.

Seemingly late in the last century the industry became aware of the additional hazards of FWD on adverse roadbed conditions and began to adopt a new transaxle shift pattern/schedule to compensate. Unlike the FEH/MMH a non-hybrid automatic transaxle vehicle does not have the ability to instantly remove engine compression braking when ABS activates, so they must do it, upshift, the instant a lift-throttle event occurs.

The Ford patent is simply a method of accomplishing the same thing for FWD hybrids.

Look at it this way, if you were driving a stick shift FWD vehicle and you KNEW the roadbed to be slippery what would be your automatic secondary reaction if/when you lift the throttle, especially a FULL lift throttle?

Depress the clutch pedal.

That's all the industry is trying to accomplish, but automatically.

Re: Cold weather causes brake failure???
 

It was a bit warmer this morning... 7 above... when I started the FEH. No warnings.

Thanks for the reminder on stored codes. I'll be sure to mention that what I bring it in.

Re: Cold weather causes brake failure???
 

I think we should all heed what wwest is saying......keep it on all the time.:shade:

Just kidding, but it is true that when you're in doubt in a front wd, aim and shoot!!

Re: Cold weather causes brake failure???
 

I've driven FWD vehicles in snow and ice all my life. I had a Dodge Horizon in HOUGHTON, MI (thats ~230" each year). Having not driven a RWD, to me there isn't really an issue... Its just different. I've always taken corners such that all braking is done while the wheels are straight... by the time I reach the corner the idea is to be going so slow such that I need the gas to pull me around the corner, and the brakes are not applied while rounding the corner.... so far its kept me out of trouble pretty well. I've never missed a corner yet in 20+ years of driving, so I must be doing something right. If I do feel it let loose... I give it a bit of gas which I think is similiar to what wwest is describing.

In Houghton I used to live on Garnet street (any MTU grads out there?)... Its got a slope on it that is just over the top. If there was any ice or snow geting down was essentially a controlled slide. You never went up unless you had chains. I remember the trick was when you were just about at your driveway you started your turn and gassed it! :) It was kind of fun acutally.

This is my first AWD vehicle.... I'm not entirely sure what to expect but you can be sure I'll take it easy.

Re: Cold weather causes brake failure???
 

Here's an update. An FEH owner in Reno reported the same issue. Her service shop reported "ABS test C1526, replaced master cyl. per TSB 05 08 05." Another owner said it is a sensor failure in the brake master cyl. in early production '05s. An online reference says DTC C1526 may occur along with DTC C1524. Another reference refers to TSB 06 10 14, "ABS light on and DTC 1475, Hybrid built between 8/2/04 and 3/30/06, Revised."

This is from a post in this forum a couple of years ago:


TSB
05-8-5 ABS AND BRAKE WARNING LAMP ON WITH DTC C1526 - DTC C1524 MAY ALSO BE PRESENT - VEHICLES BUILT PRIOR TO 2/11/2005

Publication Date: April 8, 2005

FORD: 2005 Escape Hybrid

ISSUE:
Some 2005 Escape Hybrid vehicles built prior to 2/11/2005, may exhibit the yellow ABS and the red brake warning lamps illuminating after the engine is started, and an increase in brake pedal effort. Diagnostic trouble code (DTC) C1526 (Brake Pedal Travel Sensor) will be present in the ABS module, C1524 (Brake Pedal Travel Sensor Calibration Incomplete) may also be present.

ACTION:
Install a revised master cylinder. Refer to Workshop Manual Section 206-06.


PART NUMBER PART NAME
5M6Z-2140-B Master Cylinder


WARRANTY STATUS:
Eligible Under Provisions Of New Vehicle Limited Warranty Coverage

OPERATION DESCRIPTION TIME
050805A 2005 Escape Hybrid Replace Master Cylinder (Do Not Use With 12650D, 2140A, 12651D70, 2000A) 1.6 Hrs.

Re: Cold weather causes brake failure???
 

Update update. Shop could not find anything wrong and they did not find a current error code. They tried to charge me $115 for looking, despite my extended warranty. We settled, without much hassle, for the $50 deductible.

Re: Cold weather causes brake failure???
 

I've been getting this on my 2006 FEH - no regen braking when the OAT is 25-35F. It happens after a cold start even with it garaged for the night. Eventually after driving 4-8 miles the regen braking starts to function again...this is 2-3 times as long as needed to warm up the engine and get EV mode.

When it happens, the batteries still recharge from the engine or L transmission setting so I don't think it's due to fully-charged batteries or battery temperature. It looks like a lot of you out there don't see this so I wonder what's going on?

Re: Cold weather causes brake failure???
 

It has everything to do with battery temperature.

When the battery is cold, it can take a slow charge, but not a fast one.

When braking, the regenerative brakes are about 20,000 to 25,000 watts.
A cold battery cannot accept this, so your hydraulic brakes do most, or all of the work.

However, the motor/generator can gently charge the battery, more in the 5000 watt range, when you are driving, or stopped at lights, etc.

After a few miles, the battery warms up, and the car behaves more like you are used to. I see this every day. Hope that clears up one mystery for you!
-John

Re: Cold weather causes brake failure???
 

I understand the outside/battery temperature and charging issue, but I'm still getting the brake warning light, ABS warning light, and "check brake system" message on some cold weather starts. It happened again this weekend, a few days after my Ford dealer service shop searched for, but was unable to find, any problem or current error code during a 70k service. Outside temperature was 17 degrees. The warnings came on and stayed on upon ignition start. After a minute, I turned the ignition off, waited briefly, then restarted, as was suggested here to reboot the vehicle computer. This time, all three warnings stayed on for about 10 seconds then went off. Hydraulic brakes appeared to function normally, though no regen braking due to the cold. This issue occurs only in cold weather at Lake Tahoe and never in warmer weather off the hill.

Re: Cold weather causes brake failure???
 

The ABS brake warning and the check brake system message should go out in around 3 seconds after start-up if the system is working properly. When you open the door or the dome light comes on, 12MM of brake fluid is pulled from the master cylinder to pressurize the brake system. After the system is shut down, in 4min the fluid is returned to the master cylinder.

Does anyone think the cold weather may be lowering the volume of brake fluid enough to activate a low brake fluid warning if it is close to needing fluid already? After the fluid is heated and expanded from the pressure pump and engine compartment, some fluid is then returned to the master cylinder to an exceptable level to turn off the warning lights. This would explain no codes and the check brake system and ABS warning lights going out. The manual does say that low fluid would cause a ABS warning. If you have an ABS deactivation, regen braking is also shut down.

Bottom line, try adding a little more brake fluid and post in the morning.

GaryG

Re: Cold weather causes brake failure???
 

I won't be up on the hill for another week or two. The vehicle is serviced at a sea level and warmer location. Brake fluid was checked at the 70k service, which came several days after the first incident and several days before the second. The warnings occur at 6500' in sub-freezing temperatures. Maybe lower temperature and pressure are causing a decrease in fluid volume?

Re: Cold weather causes brake failure???
 

Ogakor, going down a 6500' hill can wear the the pads which decreases brake fluid volume. If you have not changed the rear pads that wear twice as fast as the front due to regen braking, I would have them checked. Make sure the brake fluid is well above the min level also. At 70K, you have done twice the mileage as most of us. Someone may have checked your front brakes which normally wear faster, and didn't check the back brakes. Good luck, and I hope I've helped find your problem.

GaryG

Re: Cold weather causes brake failure???
 

Thanks for the suggestions. I am religious about maintaining vehicles with a good mechanic. In the case of my FEH, the 70k dealer service last week found all systems "good," including brake fluid, battery cold cranking amps, tire tread depth and tire wear pattern.

Actual brake measurements were:
Left front 7.80
Right front 7.60
Left rear 9.50
Right rear 8.80

The Ford multi-point inspection report card says "good" is "over 5mm or 7/32" (Disc) or Over 2mm or 3/32" (Drum.)"

I still suspect the brake master cyl. sensor, since that was the focus of the previously discussed service bulletin affecting my early production run '05. However, the service shop was unable to find a stored error code related to that issue.

This is my third winter in the FEH at the same Tahoe/coastal locations.

Re: Cold weather causes brake failure???
 

Have you replaced the rear brakes? If not, that information contradicts the workshop manual and the way my brakes are wearing. Also, there is no drum brakes, all four brakes are disc brakes. There is no cranking with the 12V battery either, so how would they give you a cold cranking amp reading? The standard Escape has a 590 Cold Cranking Amp (CCA) Battery, I guess they just take a reading from the 12V battery load tester. My FEH battery is rated at 500 CCA, but I know nothing about how they test that.

Let me quote section 206-00-2 of the '05 Workshop Manual Vol 2 regarging brake pad wear:

"Since the regenerative braking uses the electric motor to slow the vehicle's front wheels, front brake pad wear is reduced. The rear brake pads, because of the regenerative braking, wear at approximately twice the rate of the front brake pads."

Regen would stop or slow after the battery was full coming down a high elevation, so if you do this often, the front pads could wear faster than normal I would guess. You need to make that call.

It wouldn't hurt to add a little brake fluid past the min. level to rule that out though.

GaryG

Re: Cold weather causes brake failure???
 

Brakes have not been replaced. I'll check the fluid. Not only do I traverse a 7600' summit on the way to my weekend house, I also commute over an 1800' pass daily on the way to work. In addition, I do not pay much attention to mileage. So, I probably wear the brakes somewhat differently than others.

Re: Cold weather causes brake failure???
 

I also had the same problem last January in my '06 FEH. The dealer fix for it was to "Apply special grease to HPA connector on ACU and reprogram ABS module to latest calibration and perform air bleed ck". They also listed a "C1475 in ABS module" and referenced TSB 062201. I haven't had the problem since, but I also garage mine so I'm less likely to see it.

Re: Cold weather causes brake failure???
 

Isn't Ogakor's situation the perfect one for the use of "L" to reduce the brake wear (and possible overheating of the rotors/fluid) anyway? If thats the case you wouldn't think he'd have that much wear from the descent would he?

Re: Cold weather causes brake failure???
 

At about 30,000 miles, ALL FOUR of my brake pads are wearing the same. There was no appreciable difference between front and rear. All four were in the 10-11mm of meat on the pad remaining.

I think this is due to the fact that I use regen for 95% of my braking.
Both front and rear hardly ever hit the disc!
:shade: -John

Re: Cold weather causes brake failure???
 

Tim, you know the use of "L" isolates any use of the pads if you keep your foot off the brake pedal. The use of the brake pedal only, still uses the motor to slow down first, but you may get to the pads more often. The manual says that the brake pedal uses up to 100% of the motor for regen if the battery can take it or the motor is not too hot. I'm sure speed plays a big part also.

What I was referring too was, Ogakor's battery would get full fast relative to a long descent, and the motor would stop or slow down regen. The ABS module would then use the front pads more. Also, in his response back, he said he doesn't drive for mileage. This means he doesn't max or even try to use EV like me or GPSman. My brakes pads are wearing more from rust on the rotors than anything else now (saltwater air here).

If I had Ogakor's conditions, I would continue what I do now with "L" and "N", and keep it in EV under 40mph as much as possible, to make up for those climbs. You can also bet I would do as much climbing in EV as possible also. For those long hard climbs, my FEH would not see much over 3,000rpm's either.


GaryG

Re: Cold weather causes brake failure???
 

Just to let you know it has nothing to do with the cold.

I have had this problem with my 2006 FEH 4WD. The first time it happend was in july so cold was not an issue. Was driving and right after a cold start from being parked for 1 hour of shopping I could not stop at the first light I came to. The abs light a nd brake like came on an alarm sounded and got the message service brake system. Drove home slowly then towed to dealer. Dealer had it for three days and they could not find any codes and of course the brakes worked. Called ford headoffice they then contacted dealer and told them to replace the ECU and the HCU. I assume to make me happy. But I did not think it would.

Also this was only 16,000 KM

Guess what happend today. Drove to work in the morning everything fine.
Left for lunch and boom rolled right threw the first stop sign and same lights and warning. Only 20,000 KM

Towed to dealer again?

I'll let you know what happens.

Re: Cold weather causes brake failure???
 

Stan, look at post 19 in this thread from Ogakor, you may need a new master cylinder. Ogakor's problem does not affect stopping, just warnings and no regen.

GaryG

Re: Cold weather causes brake failure???
 

Gary I read post 19 he still had brakes and the computer found error codes. I had no brakes!!! none also the computer showed no error codes.
Turn off car wait to tow truck arives aprox 15min start the car move it for easier hockup and guess what no warning lights and the brakes are functioning properly. Took it to the dealer but the techincian is sick and it won't be looked at until monday. My guess there well still be no codes.

Anyways brake's in are not something to foul around with and a can't be testing them before I drive and do restarts until everything appears to work. Safty of me and my family is more inportant.

Re: Cold weather causes brake failure???
 

Which was the same problem I had. The brakes worked but had the warnings and lack of regen.

I agree that there may be 2 different issues here.

Re: Cold weather causes brake failure???
 

Just to be clear, did this happen in cold weather? I've had two incidents, both on sub-freezing mornings. No regen is normal in that situation, but it's odd that most of the reports of warnings from other owners also mentioned cold.

What did your service shop do about it? My dealer charged me for looking but found nothing.

Re: Cold weather causes brake failure???
 

Yes, It happened last January. I'm not sure what the exact temperature was, but January in CT is generally below freezing. Here is my previous post quoting from the dealer invoice.

All diagnostics and work was covered under warranty.

Re: Cold weather causes brake failure???
 

I'm going to throw more data here, so that people who search will find more experiences to help them out. It also seems that this thread may be similar to the thread linked here:
https://www.greenhybrid.com/discuss/...ead.php?t=4959

I have been having the same brake problems for the last 2-3 weeks. While it started when it was cold, I don't think that's the cause of the problem (esp since I'm in Seattle, where cold is actually pretty warm). I think the coldness may be a coincidence for most of us.

I've seen my problem #1 happening on this thread and others, but has anyone seen my #2 happening? Both problems started at the same time for me, and have gotten worse each day over the last 2-3 weeks.

This is what I printed on a problem sheet for my 2nd trip to the dealership (the first time they could not reproduce and saw no error codes, this time it's going to take a long weekend at the dealership until they definitively fix the problem):

#1 – Temporary ABS brake loss
·Brakes feel spongy, ABS & “service brake system” lights are on. Difficult to stop the car. This happens mostly at startup, now 3-5 times a day. Fixed after restarting car or waiting 15 seconds while the car is running (the warning lights eventually go off).
·When the brakes DO work, the brake light comes on for a few seconds every time I start to drive the car after starting up.
·The brake lights and spongy-ness have also happened twice while actively driving. I had to turn the car off at a traffic light to restore normal braking.

#2 – Complete power loss
This happens in 2 different cases:

1 – Turning the ignition.
This has happened 6 times in two weeks (4 times in last 48 hrs).
When I turn the key to start the car, all power is lost (lights, radio, dash, everything). Turning the key again doesn’t help. Power is restored only after I open the driver door then close it. All electrical settings (GPS brightness, miles-till-empty estimator, etc) are lost.

2 – Locking the car with keyless entry
This has happened 6-8 times in two weeks, most recently happening several times a day.
When I close the doors and hit the keyless “lock” button, the car’s interior lights shut off (instead of fading off) and the car doesn’t lock. When I open the car door, the lights kick up and the doors lock (and you can hear the other systems powering up). All electrical settings are lost.

I'll post back when I get an update from the dealership. Meanwhile I'm going skiing for the weekend (in a bus) and told Ford that I no longer will drive this car waiting for it to lose braking on a highway or lose power in a remote parking lot.