I've done a lot of reading and can't find a definitive answer on this one, so I'll post a new topic and see if anyone responds.

The ABS light came on in my NF a couple of years ago. At first it was intermittent, usually on but always off when it was raining, so I assumed it was an electrical fault. Eventually I got the fault codes out of it using this method:

documents.php?d=48

I forget the actual code number, but a bit of reading told me it was a solenoid and to replace the modulator. Finally did that today - mongrel of a job getting it out and the new one in. Now to the new problem:

Only error code now is 12, which means SYSTEM OK, however the ABS light is now constant. I've read that this might be the fuse or replay which is under the coolant tank, is it as simple as replacing both of these? Someone else said that it could be the reverse light fuse, but as the lights are working I'm ruling that out. Only thing I can add is that I forgot to attach the ground wire before I started the engine, which is why I'm leaning towards a blown fuse.

Could it be the diode, which I've read is next to the steering column? Or is there something under the drivers seat? (These could be different cars to the NF, which is why I'm uncertain).

Anyway, would appreciate any help.

Cheers

It could be something as simple as a dodgey plug. I get that in my au all the time, it's the passenger rear wheel sensor plug, one sensor down it shuts the system down. I'd rather drive without it anyway... it feels like when they used to make cars for men.

Yeah but wouldn't that come up with an error code?

My light stayed on. replaced faulty sensor light out, no more proplems

What's the "sensor light out"?

Not getting much help on this one.

I've got the factory workshop manual and have been looking hard at all of the schematics. The only fault that I can find is that the ABS Lamp/STO wire (pin 4 on the small connector plug coming out of the modulator) should have +9.5V with the ignition off, but it's giving me only +0.1V. With the ignition on, it's giving me the correct +2.5V.

So while I was testing the wire it occurred to me that putting a jump wire across the plug from pins 1 to 4 (picture attached) would give the ABS warning lamp the correct +12V whenever the ignition was on, thus turning the ABS light off. Was a lot easier than pulling the dash apart to remove the bulb. I did try to jump it from constant 12 volt power, but that meant when the ignition was turned off the ABS light came on - so it had to be from the ignition wire instead.

But I'd still like to get it fixed.

 

 

Attachments:

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This is the wiring diagram from the workshop manual.

What I've done is taken connection C-224 (top left) and added in a wire from pins 1 to 4.

Pin 4 from the Relay Box joins with Pin 1 from the ABS module and runs to the warning light on the dash. The manual says it is "active low to ground" so it needs +12V for the light to be off, and a lower voltage will turn the light on - I assume this is so that when the fuse blows and there is no power, the light will come on.

I can get the ABS light to flash error codes from the module (gives me code 12 - System OK), so there can't be a problem with the wiring at all. It has to be something within the module that's stopping it from working, but something that isn't putting up an error code. So I think that rules out the "normal" faults like sensors, valves, voltage, etc.

 

 

Attachments:

Fairlane 012.JPG [ 191.69 KiB | Viewed 352 times ]

I'll assume that nobody has a clue about this problem?

So I had another crack today, found all of the wheel sensor plugs and did resistance tests on all four, each one came back fine [1.2KOhm +- 0.2KOhm (Front Sensors) - 2.2KOhm +- 0.4KOhm (Rear Sensors)].

But... with either one of the rear sensor plugs undone, I could get error code 63 out of the ABS, "Valve Relay, or Valve Relay supply voltage fault". With the plugs back in, I only received error code 12 "System OK". This didn't happen with either of the front plugs - with either one or both unplugged, I still got "System OK".

So... I'm assuming all four sensors are working because they passed the resistance tests, and because I'm not getting any error codes related to the sensors. But, with any plugs undone I should have got an open circuit error code (31 FR, 32 RR, 33 FL, 34 RL). I'm not sure if I should have got error code 63 for any reason related to an unplugged sensor.

Logical conclusion is that the modulator is stuffed. But I had the same problem with the previous modulator, so I think we can rule that out, unless an electrical fault wrecked both modulators in succession.

Any thoughts? Nobody else seems too interested in this, but I've put so much f**kin time into this now I'd really like to get it fixed!

try cleaning the encoder rings and the pick up heads,that worked for me