ABS Sensor - no fault codes

H

heppers

Member
My ATL90 has developed what appears to be an ABS fault - moments after driving off, it puts up a RED brake warning light and beeps three times. I'm presuming it's lost one of the wheel sensors, but using an OBD tool reveals no fault codes lodged in the ECU, and it drives fine, brakes are fine (not tested ABS kicking in to be fair).

What could be the cause, and how do I diagnose the fault?

Any ideas appreciated.
 
heppers said:
My ATL90 has developed what appears to be an ABS fault - moments after driving off, it puts up a RED brake warning light and beeps three times. I'm presuming it's lost one of the wheel sensors, but using an OBD tool reveals no fault codes lodged in the ECU, and it drives fine, brakes are fine (not tested ABS kicking in to be fair).

What could be the cause, and how do I diagnose the fault?

Any ideas appreciated.
Click to expand...
Is it the brake drum graphic, in red?
If so, it's telling you you have a brake problem. There is no OBD fault code, because there is no faulty component, it's a valid warning to a condition in the braking system. Worn pads, or broken pad sensor wires perhaps?
Mac.
 
PlasticMac said:
Is it the brake drum graphic, in red?
If so, it's telling you you have a brake problem. There is no OBD fault code, because there is no faulty component, it's a valid warning to a condition in the braking system. Worn pads, or broken pad sensor wires perhaps?
Mac.
Click to expand...
Think that pads related is small yellow warning, big red with exclamation would be lack of fluid
 
heppers said:
My ATL90 has developed what appears to be an ABS fault - moments after driving off, it puts up a RED brake warning light and beeps three times. I'm presuming it's lost one of the wheel sensors, but using an OBD tool reveals no fault codes lodged in the ECU, and it drives fine, brakes are fine (not tested ABS kicking in to be fair).

What could be the cause, and how do I diagnose the fault?

Any ideas appreciated.
Click to expand...
to check ABS sensors you could just check each wheel ABS speed reported as you have VCDS so then you know if one is off - dont think ABS gives red warning tho, i would expect yellow for it tho.
 
Definitely not ABS, as no ABS Warning.
robskiA2tdi said:
to check ABS sensors you could just check each wheel ABS speed reported as you have VCDS so then you know if one is off - dont think ABS gives red warning tho, i would expect yellow for it tho.
Click to expand...
If was ABS, you'd get an ABS warning on the dash.
Screenshot 2024-04-16 16.14.22.png

Mac.
 
Brake light switch? That throws no OBD codes either. If you have cruise control, it won't engage if the brake light switch is faulty as a safety measure (although I think it will still engage if there is an ABS fault).
 
Brake switch fault would cause the glow plug light to come on, so doubt it is that. ABS fault would put the ABS warning light on.

What is the fluid level in the reservoir and when was it last changed?

What work has been done on the car?

Any other warning lights?

Have a VCDS scan done incase your reader is not suitable.
 
The post is titled "ABS Sensor - no fault codes"
Just an incorrect assumption by the OP I think. Easy mistake to make, if you don't have a quick look in the manual, or on here, to check what dash symbols mean.
Mac.
 
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