ABS fault - Testing/checking?

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icyleaf

Member
Joined
Jan 15, 2025
Messages
5
Location
Iceland
Hi, long term leaf owner, but looking at buying a 2012 leaf a town runabout for my son. We know it has some faults (currently owned by a friend), so I'm trying to work out what we will need to fix before I commit to buying it..

Key DTC faults via leafspy are
C1111 - ABS pump
C1A70 - Brake control system
There is also
U1000 HVAC CAN, but I'm not too worried about this right now

After a helpful root around the forum, my plan is
1. Charge 12v battery fully/try and swap for a newer battery as a test as I gather low bat voltage can cause odd faults (perhaps the battery from my 2019 leaf will fit)
2. Order some brake pressure sensors (47240AL500) in case they fix the C1A70 issue
3. Check the fuses and supplies to the ABS unit
3. Be prepared to try and track down a replacement ABS pump/valve unit to replace the existing one

On the ABS, should I hear/feel the pump spin up when the vehicle is powered up, or just when the ABS self test kicks in at low speed (5-10mph?)? I suspect I'll need to replace this, but I'd rather not pay for a unit (and shipping to Iceland) only to find this isn't the issue.

On a similar vein, does anyone know what the '>' character before a DTC error code in the leafspy list means (e.g >C1111)? I can't find a mention of it in the user manual. I'm guessing it indicates the error is current/ongoing, as I can't clear these from the system, but it's just a guess.

Many thanks in advance from an unseasonably warm Iceland
 
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I don't have a 2012 Leaf but I've owned numerous cars with ABS over the years. In my experience, the only time you will notice the ABS pump is when it is needed, eg when trying to stop on ice. You could try to test it out on some slippery surface since its function is to prevent the wheels from locking up when braking.

I'd also recommend just clearing all the codes and see if they come back. Some times codes are listed when the actual failure occurred months or years in the past or was an intermittent condition. Real failures should throw a code after being cleared.
 
I don't have a 2012 Leaf but I've owned numerous cars with ABS over the years. In my experience, the only time you will notice the ABS pump is when it is needed, eg when trying to stop on ice. You could try to test it out on some slippery surface since its function is to prevent the wheels from locking up when braking.

I'd also recommend just clearing all the codes and see if they come back. Some times codes are listed when the actual failure occurred months or years in the past or was an intermittent condition. Real failures should throw a code after being cleared.
Hi goldbrick,
Yup, I was hoping a code clear might help, but the 2 main issues don’t clear sadly. I agree ABS is something I could live without. I have spent much of my life driving various trucks and cars without ABS. However, the new leaf has failed its annual test on this, so I need to fix it asap.
 
On a similar vein, does anyone know what the Yes, the '>' character before a DTC error code in the leafspy list means (e.g >C1111)? I can't find a mention of it in the user manual. I'm guessing it indicates the error is current/ongoing, as I can't clear these from the system, but it's just a guess.

Many thanks in advance from an unseasonably warm Iceland

Yes, the '>' character means it is a live code so cannot be cleared.

Have you checked the 12v battery voltage ?
It might just need a long slow charge to bring it back to full life, preferably with a desulphating charger.
 
Yes, the '>' character means it is a live code so cannot be cleared.

Have you checked the 12v battery voltage ?
It might just need a long slow charge to bring it back to full life, preferably with a desulphating charger.
Thanks for the LeafSpy confirmation, didn’t see this mentioned in the docs. That matches my experience of not being able to clear the errors
Tried a long, slow charge. Sadly no change I also don’t hear any sign of an ABS self-test (buzzing noise!?) when I get to low speeds when driving, although I can’t say I remember hearing this in leafs with working ABS before, so perhaps I missed it?
Obviously I’d be really happy to find it was a bad battery issue. I might try and jury rig up a spare 120Ah 12v bat in the passenger footwell in parallel with the current one and go for a short test drive, as this should make voltage drops unlikely.
Also still need to check the 12v feed to the ABS pump, but chickened out of testing this in the driving snow today..
 
In my case it was just a poor contact on the pressure sensor. I used some Nano protech and it fixed the issue. There are also I think two big connectors for the ABS. Disconnecting and reconnecting those might help too. I hope you fix it for free.
 
In my case it was just a poor contact on the pressure sensor. I used some Nano protech and it fixed the issue. There are also I think two big connectors for the ABS. Disconnecting and reconnecting those might help too. I hope you fix it for free.
Oooh! That would be great if that was the issue. I must make time to disconnect the connectors and check them. I planned to do this anyway as I want to be sure I’m getting power to the unit.

What pressure switch did you fix? The ones on the brake cylinder? I seem to have 2, I think this changed to 1 on later models. Awaiting 2 replacements just in case (generic, not the official £300/sensor ones from Nissan)

Sadly I spent yesterday evening under my youngest son’s Nissan Navara examining the remains of its rear diff (pinion gear failed and filled the diff with expensive bits of metal), so didn’t get to the leaf. Tonight was spent doing electrical stuff on my elderly Landrover..

I did splash out on a new battery which has been on charge for 24h. Just in case this helps. Don’t know the history of the current one. Hopefully if the snow holds off I might get to play on the leaf tomorrow.
 
Oooh! That would be great if that was the issue. I must make time to disconnect the connectors and check them. I planned to do this anyway as I want to be sure I’m getting power to the unit.

What pressure switch did you fix? The ones on the brake cylinder? I seem to have 2, I think this changed to 1 on later models. Awaiting 2 replacements just in case (generic, not the official £300/sensor ones from Nissan)

Sadly I spent yesterday evening under my youngest son’s Nissan Navara examining the remains of its rear diff (pinion gear failed and filled the diff with expensive bits of metal), so didn’t get to the leaf. Tonight was spent doing electrical stuff on my elderly Landrover..

I did splash out on a new battery which has been on charge for 24h. Just in case this helps. Don’t know the history of the current one. Hopefully if the snow holds off I might get to play on the leaf tomorrow.
Hi, just a follow up, as it looks like I have managed to get everything working again.
The ABS fault seems to have been a bad/worn motor in the ABS pump. Replacing the unit with a 2nd hand unit solved the issue and cleared the C1111 code.
On dismantling the old unit I found that the motor would only spin if hand started, or if it just happened to stop in a ‘good’ position. It’s a sealed unit, and I couldn’t find new motors for sale.
I was worried that the C1A70 code was still present after repairing the ABS, as I was pretty sure the brake pressure sensors etc were ok (got a fault if I disconnected them, which cleared on reconnection). Thankfully after bleeding the brake system the C1A70 code cleared and all seems well.
Still a few jobs to do (2 new tyres, replace both front lower arms (worn bushings)) but it looks like my son is the proud owner of a cheap leaf.
Many thanks to the community for all the helpful comments and replies. Guess the next job is rebuilding the diff on my other sons Navara :(
 
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