Regen Brake Stop Working

[seetohcw]

I've been driving my '17 FFE, everything is fine till yesterday when regen stop working.

- Foot off the pedal... no regen at any speed.
- Fully charged... same issue the next day.
- L drive... no regen at any speed.

Any one has any experience with this? or advice?

Thanks.

[skyguy_6153]

Regen doesn't work if the battery is fully charged, it should activate after a bit of driving though.

[seetohcw]

Thanks. It has gone down a bit, no longer 100% (currently at 75%) and still no regen.

[Heima]

Anti_Climax said this in another thread:

Re: Feeling a punch when braking at higher speeds
Quote
Sat Nov 20, 2021 4:12 pm

One thing I'd look - there's a switch on the brakes, separate from the one that triggers the lights, that cuts motor power. It keeps it from wasting energy trying to creep while you're at a stop, but if it were to stick during normal braking you'd feel an abrupt change when it unsticks. Don't have much else to offer.

Maybe this switch is sticking?

[Anti_Climax]

The regen should kick in separate from that switch - taking your foot off the accelerator should kick it on and it should stay on even if you hit the actual brake pedal. So stuck in either position, they should be seeing that.

Best I can tell, the car manages regen based on drivetrain load. The car estimates, from speed, the amount of energy in play versus what's been "requested" by the accelerator and when there is an excess in that calculation, it kicks into regen mode.

Looking in the maintenance guide for this, there is a regenerative braking calibration mode in the scan tool, regen itself is managed by the TCM, so you may want to check all the relays and fuses that associate with it. It coordinates with ABS as well.

The guide also suggests it is possible for the system to lose some of the stored parameters and throw a fault code as a result. It notes that certain brake system faults can cause it to simply fail over to friction braking only - many of the components that help manage the transition from friction to regen are being monitored and recurring faults will shut it it off. That should trigger a code, not sure if it would actually trigger an indicator on the cluster if "braking" still works.

"If the ABS module detects that the brake booster is not able to build adequate hydraulic brake pressure in the master cylinder, the brake system transitions from regenerative braking mode into friction braking mode. While in friction braking mode, the ABS module continues to test the brake booster. If the brake booster begins to generate the expected amount of pressure in the hydraulic system, the brake system recovers into regenerative braking mode. If the brake system has to transition from regenerative braking mode to friction braking mode 3 times in the same ignition cycle because of a brake booster performance fault, the brake system downgrades to friction braking for the rest of the ignition cycle."

I also learned something nice:

Brake Modes

Because much of the brake torque required to stop the vehicle can be achieved through regenerative braking, it is not always necessary for the conventional friction brakes to be applied. The brake pedal uses a pedal feel simulator that acts against a curved bracket to give the driver a simulated pedal resistance as the brake pedal is applied. The ABS module uses the driver input on the brake pedal, wheel speed sensor input and the lateral deceleration messages from the RCM to determine the amount of deceleration the driver is requesting and which brake mode is necessary.

[seetohcw]

Thanks.

Assuming it's something with the TCM... is that covered under FFE hybrid/electric 8 years 160km warranty???

It must be either transmission or the hybrid/electric charging system that's off.

Is there a way, to reboot the system? (like how you turn off and on electronics?)

Right now, when I coast, there's no regen / not slowing down... either in D or L.

[Anti_Climax]

Pulling your 12V off the battery should force everything to at least fully power-cycle.

The TCM is what sits between the battery and the motor, so I cannot conceive that it's not part of that drivetrain warranty.

[Focus_pilot]

Might try and rest it via FORScan.

[seetohcw]

Thank you everyone for contributing.

Update: I booked an appointment with Ford but a one day the appointment, the regen came back. it's working normally again.

I don't know why. Maybe the TCM reset itself?

Hope it stays that way.

Just want to say thanks to the community here.

Still enjoy driving my FFE.

[Anti_Climax]

I had a weird intermittent problem too - I'd back out of my driveway, put the car in drive, get down the road to a stop sign and, after stopping, the car would not creep when I took my foot off the brake. Level ground, it had to have been working to go into drive after backing out. Would never happen for the dealer.

At least it stopped, probably from a software update...