Hi all
Have a trailer which the abs light came on when going above 50mph so we tightened the wheel bearings which didnt help so we then replaced the discs which has cured the ober 50mph problem but now when the driver presses the footbrake the abs light comes on but goes out again we he takes his foot off of the brake pedal any ideas what could cause this?
Thanks charlie
Hi, is this the same trailer that doesn’t blow down when the abs Suzie is plugged in? Or the same tractor unit?
If it is the same tractor unit and trailer I would check the trailer abs fuses in the tractor unit as in your other post that would cause the fault code you describe. The abs light may be coming on then off again at speed when you press the foot brake as the abs system can’t power up from the abs Suzie, so it will only power up from the brake light circuit when the pedal is pressed.
Hi
Different unit and trailer
Thanks
Hi Charlie, does the trailer have a green light on the headboard? And does it blow down when you turn on the ignition?
Hi blows down and goes on off and on
Also checked fuses on the magnum and none were blown do you have any other ideas as to what it could be?
Thanks
Does the tractor do the abs light thing with another trailer or just this one?
Havent checked yet as we had to attend a breakdown today so didnt get a chance but when another lorry is hitched up to the trailer it is fine and the trailer blows down as should whereas with the magnum it does not blow down
Thanks
Is the abs socket ok on the magnum? No bent or missing pins or damaged housing? Other than that try chasing the wiring back from the socket to the loom to check for broken wires? Don’t have experience of magnums only Volvo but are there any fault codes on the magnum?
Will have a look tomorrow from a quick inspection the pins all looked good thanks for all your help
Sound like a tractor problem, let me know how you get on.
Will do thanks
I’m a bit worried that on every post regarding ABS faults your goto solution seems to be tightening wheel bearings and it really shouldn’t be unless they’ve been done to an incorrect spec to start with.
Generally the faults will be dud wiring, dud sensor or most commonly sensor gap or an issue with the teeth of the exciter ring. Yes it’s certainly the case that ABS issues can be an early warning of a hub/bearing on their way out but I certainly wouldn’t assume that.
If corroded exciter ring teeth are the issue, unless the disc is badly worn anyway, you don’t necessarily need to replace you can wire brush the teeth or in cases of extreme corrosion use a Dremel. Usually, as you, say the fault occurs over a certain speed, when the signal the sensor reads loses too much definition, so it isn’t usually too hard to ascertain if you’ve had the desired effect.
There are handheld diagnostics that will plug into the two pin connector to the sensor so you can spin the wheel by hand and check the signal also.
If you have cured your headboard on at over 50 mph problem, then it sounds as if the system is working correctly now if the light is on as you describe with the artic stationary and handbrake on.
You need 3 lives at the ABS lead.pin 1 for solenoid valve feed pin 2 for electronic trigger valve and pin 5 for sensing.Pin 3 and 4 are earths.
The other 2 (6 and 7) are can high and can low.(EBS)
The “blow down” is a self test of the solenoids and on a single sensed axle you should get 2 pops one for each side.
boyesadabest:
Will have a look tomorrow from a quick inspection the pins all looked good thanks for all your help
If its an older trailer check pin 1 for continuity as on some older ABS sockets pin 1 is a fuse to protect the tractor ABS ecu.So even if power is going to pin 1 in the lead it wont pass through the abs socket.
there is only 2 positives / lives /feeds
As Coiler says it sounds like it’s powering up from the brake light circuit.
norb:
there is only 2 positives / lives /feeds
Then thats why its not working
On the magnum we narrowed it down to the connection on pin 2 had broken off now is perfect