Seeking Advice Regarding My Damaged LeaF

[LeftieBiker]

The master cylinder and control module is one assembly that Nissan calls the intelligent brake controller and $2800 is about the cost for replacement at a competent Nissan dealer. The unit on my 2015 was recently replaced due to intermittent internal problems causing communication errors on the CAN Bus (which caused very abrupt brake application along with very loud, continuous ABS operating noises when depressing brake pedal). It might be possible to buy a used unit cheaper, but the decision maker for my extended warranty finally gave up searching and authorized the dealer to install a new unit. I know that associated DTCs can be cleared with Leaf Spy Pro because I was able to reset mine several times over the past few months before finally taking it to the dealer. Resetting required clearing codes, disconnecting/reconnecting 12-volt battery, and clearing codes again (sometimes required repeating the process two or three times). Therefore, a competent independent mechanic should be able to replace the unit, bleed the brakes, and then use Leaf Spy to clear the DTCs.

That was my understanding. The ABS valves are usually on the calipers, and can be bled manually. Some mechanics won't work on ABS systems (which can usually be driven with ABS disabled and a warning light staying on) but most will now, as it becomes almost universal.

 

[TLeaf13]

The master cylinder and control module is one assembly that Nissan calls the intelligent brake controller and $2800 is about the cost for replacement at a competent Nissan dealer. The unit on my 2015 was recently replaced due to intermittent internal problems causing communication errors on the CAN Bus (which caused very abrupt brake application along with very loud, continuous ABS operating noises when depressing brake pedal). It might be possible to buy a used unit cheaper, but the decision maker for my extended warranty finally gave up searching and authorized the dealer to install a new unit. I know that associated DTCs can be cleared with Leaf Spy Pro because I was able to reset mine several times over the past few months before finally taking it to the dealer. Resetting required clearing codes, disconnecting/reconnecting 12-volt battery, and clearing codes again (sometimes required repeating the process two or three times). Therefore, a competent independent mechanic should be able to replace the unit, bleed the brakes, and then use Leaf Spy to clear the DTCs.

My car would make terrible noises too whenever the brakes were pressed, but it happened every time instead of intermittently like yours. For some reason taking out the VDC fuse stopped those noises and made the car driveable, but still not normal. An earlier post indicated using a "generic" mechanic was a bad idea. But since it's a part even ICE cars have, I don't see why it would have to be repaired by the Nissan dealer. If it's just about clearing the codes, I do have LeafSpy Pro so that's not a problem. I've cleared the codes before when I was initially troubleshooting this problem.

It seems like Nissan's "intelligent brake controller" is kinda lousy. Was yours replaced under warranty? If so, which warranty was it covered under? I had reported this issue to http://www.safecar.gov and there were a few other reports similar to mine. I wonder if this is a relatively common problem that should result in a recall.

 

[TLeaf13]

Thanks everyone for your replies. It sounds like it might be best to first have a trusted local mechanic diagnose the car and give me a repair quote. If I can get it fixed for a reasonable price, it might be worth fixing. Unfortunately the only mechanic I knew I could trust died a couple years ago. The time has come for me to find a new mechanic. Hopefully a local mechanic can be more specific for me than the Nissan dealer who wrote "brake unit internal." I'm not sure what exactly the dealer means by that statement. My best guess is something I found on eBay called "power brake booster master cylinder."

Probably. There may also be a control module that failed. How much is the (hopefully new) part on Ebay? Labor for a new booster/master cylinder unit installation, including a brake line flush, shouldn't be more than $500, done away from a dealer. It could be less.

The part I found on eBay is listed around $330 and up from various sellers. If there is a control module that failed, I am not sure what to look for. Which leads me back to seeing if I can have a local mechanic diagnose what is wrong and if it can be fixed for a reasonable price. If I have to take it to the dealer to be fixed for $2,800, I really am not sure that it would be worth it.

 

[LeftieBiker]

See Gerry's post above.

 

[GerryAZ]

Maybe my earlier posts were not clear. When the intelligent brake controller caused CAN Bus communication errors, the brakes would be very abrupt and there was continuous noise from the ABS module whenever the brake pedal was depressed. The only way to make the brakes, ABS, and stability control systems work correctly again was to clear all of the associated DTCs (which generally required disconnecting/reconnecting the 12-volt battery in addition to using Leaf Spy--repeating several times, if necessary). I called it an intermittent problem because the car might go several months without issue after clearing the DTCs before it happened again. I think the car was only a couple years old the first time it happened, but it became more frequent in the last few months. The last time, it happened when I started the car to go to work after charging overnight. The car was due for its annual battery check so I called the dealer, said I was bringing it in, and carefully drove there (about 10 miles). When the service advisor walked up to the car, he asked if it was still making noise. I stepped on the brake pedal without saying anything and he was really surprised by the loud, continuous noise.

Please read the description of the intelligent brake controller in my earlier post. The control module is an integral part of the brake master cylinder and hydraulic booster assembly. The repair for my car was covered by the aftermarket extended warranty. The labor was not much (basically the same as replacing a conventional master cylinder), but the price of the part was well over $2,000. You may be able to make the brakes and ABS function correctly for a while by replacing removed fuse(s) and clearing all DTCs using the procedure in my earlier post.

 

[DaveinOlyWA]

I have a 2013 Leaf SL that has major problems. The "brake unit internal shorted" according to the dealer. They want $2800 to fix it. The traction battery has only 8 bars and I missed the degradation warranty by 5 months. I'm also way overdue for new tires. I think it still has the original Michelin Energy Saver tires with about 44,000 miles and they look terrible. I still owe around $6,500 on my loan.

It doesn't seem worth repairing or getting new tires for it mostly because the traction battery is terrible. It only has about 63% of its original capacity. I would have to refinance the loan and/or get a new credit card to pay for the $2800 repair. If I were to get rid of the car, I don't have any idea how. I don't think anyone would even take it on a trade in. Do you think I'm stuck having to repair this car? Should I fork out the money for new tires? If your opinion is that I dump this car, how do I accomplish that? I'm sick of having to press super hard on the brake pedal all the time and am very worried about the tires.

Thank you for your advice!

(I also posted this on reddit/r/leaf but am not sure how many users here also use Reddit.)

Its tough to give a good answer to someone still in the process of filling out their user profile but...

Fix it, get new battery and enjoy driving it for XX or XXX thousand miles. You will NOT get the same battery you had. It will be better and we have some who have exceeded 125,000 miles on theirs with 93% SOH.

 

[SageBrush]

It will be better and we have some who have exceeded 125,000 miles on theirs with 93% SOH.

"Some."
What percentage ?
I have read of some people who win millions in a state lottery.

 

[lorenfb]

That was my understanding. The ABS valves are usually on the calipers, and can be bled manually. Some mechanics won't work on ABS systems (which can usually be driven with ABS disabled and a warning light staying on) but most will now, as it becomes almost universal.

That's not correct, i.e. "ABS valves on the calipers", based on the standard design used by most ALL OEM automotive manufacturers.
All four wheel caliper brake pressures are controlled by the ABS hydraulic unit which typically has the brake ABS ECU integrated.
As part of the ABS ECU function is the traction/stability control function. Each wheel or set of wheels has its own wheel speed sensor.
By monitoring the deceleration of each wheel's speed, the likelihood of a wheel losing traction can be determined. On ICEVs, the
ABS module typically has a high failure rate, given its placement in the high temp engine compartment, i.e. sometimes placed
near the exhaust manifold. Resulting vibrations based on the unit's mounting can cause intermittencies.

 

[LeftieBiker]

Time marches on. I haven't seen an ABS unit up close since the Nineties, if ever. The point remains that any good independent mechanic can replace an ABS control unit.

 

[lorenfb]

Time marches on. I haven't seen an ABS unit up close since the Nineties, if ever. The point remains that any good independent mechanic can replace an ABS control unit.

Some ABS units may require coding (assign a CAN address) to the vehicle, i.e. using the Nissan Consult tool.

 

[TLeaf13]

Maybe my earlier posts were not clear. When the intelligent brake controller caused CAN Bus communication errors, the brakes would be very abrupt and there was continuous noise from the ABS module whenever the brake pedal was depressed. The only way to make the brakes, ABS, and stability control systems work correctly again was to clear all of the associated DTCs (which generally required disconnecting/reconnecting the 12-volt battery in addition to using Leaf Spy--repeating several times, if necessary). I called it an intermittent problem because the car might go several months without issue after clearing the DTCs before it happened again. I think the car was only a couple years old the first time it happened, but it became more frequent in the last few months. The last time, it happened when I started the car to go to work after charging overnight. The car was due for its annual battery check so I called the dealer, said I was bringing it in, and carefully drove there (about 10 miles). When the service advisor walked up to the car, he asked if it was still making noise. I stepped on the brake pedal without saying anything and he was really surprised by the loud, continuous noise.

Please read the description of the intelligent brake controller in my earlier post. The control module is an integral part of the brake master cylinder and hydraulic booster assembly. The repair for my car was covered by the aftermarket extended warranty. The labor was not much (basically the same as replacing a conventional master cylinder), but the price of the part was well over $2,000. You may be able to make the brakes and ABS function correctly for a while by replacing removed fuse(s) and clearing all DTCs using the procedure in my earlier post.

I see what you're saying now. When this problem first occurred, I did try clearing the codes and disconnecting the battery multiple consecutive times. But the problem persisted. I found my original post regarding the "brake unit internal" issue from about 1.5 years ago. You had actually provided a piece of advice that I forgot to consider. You wrote: "The brake unit noises with the VDC fuse installed indicates that it has power and is somewhat functioning (pulsing hydraulic pressure to at least some of the brake calipers). I would look for problems with sensors, wiring, etc. associated with the ABS and VDC systems before replacing the expensive brake unit."

I'm not sure how to go about looking for problems with the sensors and wiring. I could probably have a mechanic check those. One of the error codes shows that there is a problem with the "Brake Motor Power Supply." I think that probably leads to the other code of "ABS E-Driven Int Brake System." These are the codes:

C118A 0109 ABS E-Driven Int Brake System BRC-124
C1A61 0109 BRAKE Motor Power Supply BR-46

I greatly appreciate the information and advice from you and everyone else here!