MNizlek Posted August 12, 2019 Report Share Posted August 12, 2019 The following forum entry was submitted to an issue posted several years ago. I am repeating it here, since we have not been able to find a solution here or via our dealership. We have a 2013 Hybrid SE. Hill Start Assist on our 2013 vehicle has recently started acting up. (Down Grade Assist has been an issue as well. More on that below). We live on a hillside. To exit our drive, there is a short level section as we back from the garage. As you back, you turn to aim up the driveway. Inconsistently, after you apply the brakes and shift to Drive (or Low), on accelerating the car bucks and jerks stopping for a second. This same condition will occur in traffic when stopped on a grade; but again inconsistently. (This is of major concern, since the car starts forward, then suddenly jerks to a stop and drivers behind us have nearly plowed into us.) Timing seems to be a factor. If you wait more than about 2 seconds between removing your foot from the brake pedal and pressing the accelerator, chances are higher it will occur. Subsequently an unusual sound will occur following the jerking; like the tranny is in some other gear, but that's speculation on my part. If you have any information on cause and resolution of this, please advise. The (down) grade assist feature, since early in our ownership, has had an issue as well. If activated for a down grade, then turned off nearing the bottom of the hill, one needs to pump the brakes before braking to a stop. If you don't do this, and apply the brakes to reach a full stop, the car will jerk twice as it stops; but again, this is inconsistent. These jerks are not nearly the magnitude as the Hill Assist issues, above, but are a concern. We have stopped using this feature, but would like it, if repairable. We have videod the issue. It is parked online for review. Here is the link - https://1drv.ms/v/s!Ap1n9TQWS-TDkh4e3zMAEeY3j7kt?e=xTwOeh Yes, our dealer has checked for and assures us that all applicable reprograms/TSBs have been installed. Quote Link to comment Share on other sites More sharing options...
fbov Posted August 12, 2019 Report Share Posted August 12, 2019 This sounds like it might be an accelerometer issue. Some early builds, like ours, had a bad RCM. I blew mine in August, 2014, and they couldn't replace it until October. After replacement, they performed the 14S04 recall. You may want to look into service actions performed in conjunction with the 14S04 recall, if you can access the service records. It was a pothole, hit really hard, that blew the RCM, and turned my dash into a Christmas tree for a few months. That's why I mention the accelerometers; mine were fragile enough a pothole killed them. If your RCM is still original, that's where I'd look. HAve fun,Frank Quote Link to comment Share on other sites More sharing options...
plus 3 golfer Posted August 14, 2019 Report Share Posted August 14, 2019 (edited) Did you show the video to the dealer? Clearly, something is amiss. What's the grade when you back out and stop? Is car level, uphill or downhill? Steering wheel is turned going backward. Then, when shifted to D, it appears that the "jerking" occurred as soon as the steering wheel was turned to go forward and then twice more as wheel is turned. Does the bucking happen if you pull back towards the garage and not turn the steering wheel? Do you know if the event happens if you accelerate briskly from a stop? The whooshing sound occurs after the jerk which, IMO, is air rushing into the vacuum booster. "The ABS module continually monitors the vacuum in the brake booster through the use of a vacuum sensor. When the vacuum sensor indicates vacuum is below a predetermined level during a braking event or if the driver attempts to stop the vehicle with a low vacuum condition in the brake booster, the ABS module activates the hydraulic pump motor in the HCU to assist with vehicle braking." So, when you shift from R to D, hill start assist should auto kick in which should hold the car in place for about 1.5 seconds to allow transition from brake pedal to accelerator. The car will be held in place until there is sufficient torque requested by the accelerator pedal to move car forward at which time the brake pressure is reduced to allow car to move. But what happens if there is low vacuum (maybe faulty sensor, leaky vacuum valve) and the hydraulic pump kick in to assist to hold car in place and then vacuum is OK momentarily and the pump shuts down but kicks in again at slow speeds? Will the car jerk? I don't know but it could be a spike in hydraulic brake pressure if pump cycles on/off at low speeds that will easily stop vehicle. Also, the fact that you have to pump brakes a few time after turning off grade assist so as not to get jerking seems to point brake booster / low vacuum. OPTIONS: 1) Try another dealer (but problem may be above dealer tech pay grade).2) Open a case with Ford via phone (you can ask dealer if they will do it) to get their engineers involved. Point to safety issues and ask for a knowledgeable person to call back and send them the video link. 3) I believe that by recording data when this event happens, one can analyze the data, and more than likely find why this event happens. With the ForScan App and an OBDII adapter, one can record data, load data into excel and graph data. I believe one can assess whether certain components are OK like the RCM, sensors and so forth.4) Do you know if brake lights come on when the jerk happens, if not, then NHTSA may consider this event as a safety issue. You can file a complaint with NHTSA and also look at complaints filed that may be similar to this. Edited August 14, 2019 by Plus 3 Golfer Quote Link to comment Share on other sites More sharing options...
MNizlek Posted August 21, 2019 Author Report Share Posted August 21, 2019 Plus 3 - thanks for the comments. I will pursue your suggestions and report back. Quote Link to comment Share on other sites More sharing options...
MNizlek Posted August 28, 2019 Author Report Share Posted August 28, 2019 Plus 3 - my apology for not getting back sooner. In your first paragraph you asked several questions. Here are answers to several - > Did you show the video to the dealer? Yes, they were supplied this and one earlier video. > What's the grade when you back out and stop? Is car level, uphill or downhill? When backed, the grade is uphill at a pretty steep angle. However, we have had the jerking occur on slight grades as well as on level ground.> Steering wheel is turned going backward. Then, when shifted to D, it appears that the "jerking" occurred as soon as the steering wheel was turned to go forward and then twice more as wheel is turned. This is correct.> Does the bucking happen if you pull back towards the garage and not turn the steering wheel? Have not tried this, but will do so.> Do you know if the event happens if you accelerate briskly from a stop? Yes. The jolt is greater, the greater the attempt to accelerate. So, to gain the hill from our driveway, one has to accelerate. Once in traffic on a slight slope, accelerating from the signal at a normal rate you would use in traffic, the car jolted to a complete stop. The car behind nearly plowed into us. Quote Link to comment Share on other sites More sharing options...
plus 3 golfer Posted August 28, 2019 Report Share Posted August 28, 2019 There are only two possible sources for the abrupt slowing down (jerking): the traction motor applies significant regeneration force to the output shaft or the ABS applies brakes. I believe there would be too many checks which would prevent regeneration kicking in at such low speed, in D and accelerating even if several sensors failed. So, that leaves the ABS system. So what can cause the brakes to be applied normally without brake pedal when accelerating? failure of sensors like wheel speed sensors, pitch and yaw sensors (located in RCM), steering wheel sensor which may trigger a stability / traction control event to which the ABS system reacts by applying appropriate braking. Turn off Traction Control in the left hand display (I think it's under information, settings / driver assist) and see if you still get the jerking. Stability control will still be enabled as that cannot be turned off. Quote Link to comment Share on other sites More sharing options...
fbov Posted August 29, 2019 Report Share Posted August 29, 2019 ... Stability control will still be enabled as that cannot be turned off.Before my RCM failed, I had one case where the car applied the brakes on it's own in the middle of a turn. I assumed it was an overaggressive skid prevention system. Given it has never happened again, I now think it was a symptom of the bad RCM. We're both 2013's... Best of luck,Frank Quote Link to comment Share on other sites More sharing options...
MNizlek Posted September 9, 2019 Author Report Share Posted September 9, 2019 Plus 3 - I have had to transfer my video files to Amazon's cloud as I have more space there. The link is - https://www.amazon.com/photos/shared/vm1qB6S4QlK9HhHUBRyFEg.QD-VW-xobjA9KSOnVTNvhv There are several additional videos of the backing issue. You asked to show one from the rear to determine status of the brakes. I can't tell for certain, but it appears they don't stay on. It's difficult to tell, since my reaction as soon as the vehicle jerks is to step on the brake. See what you think. We did attempt your suggestion to back up, then come forward, to see if it occurs then. It did not, but we'll try it again, since the event only occurs about 50% of the time. I have not attempted to turn off traction control yet. Again, thanks for your help. Quote Link to comment Share on other sites More sharing options...
MNizlek Posted October 15, 2019 Author Report Share Posted October 15, 2019 To complete this topic, our dealer has replaced the transmission. This appears to have resolved the issues described above. fbov 1 Quote Link to comment Share on other sites More sharing options...
C-MaxA2 Posted October 15, 2019 Report Share Posted October 15, 2019 Thanks MNizlek for the follow up. Too many times here you never hear of the final resolution of an issue. Quote Link to comment Share on other sites More sharing options...
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