Abs & ebs problems

Hello,
my name s baz, i do ABS/EBS diagnostics on commercial vehicles for a living,
if anyone has any questions please feel free to email me and i will do my best to answer them for you.

it would help if you could give me some information on the ABS/EBS system you are asking about, (ecu part number/truck or trailer fault for example)

i am offering my help totally for free in my spare time, i will do my best to answer any questions as soon as possible.

thanks

Welcome to Trucknet bazabs

Welcome on board bazabs :smiley:

Welcome to the forum and thanks for the kind offer

Jacko :smiley: :smiley: :smiley:

Well, seeing as you offered…
07 Midlam 170, the ABS warning came up last week together with the
little orange triangle.
The brakes performed normally, whilst the warning was up, as far as I could tell.
As with other warnings, I switched off the ign, then started again. Warning cleared, and no sign of it since.

Now I have a technical background, and i’m not easily fooled by computers.
Plenty of drivers would have stopped asap, phoned the office, and refused to drive until a technician had ok’d it.

The next day, while unladen, I tested the brakes including the ABS on a wet clear road, all worked as designed.

Actions?

'kin 'ell, i’m still on vacuum brakes!! :laughing:

What u driving Viking?

Jacko :slight_smile:

Why do Daf tractor units always come up with EBS TRUCK WARNINGS?
What is the common reason for this and can it be reset without a computer?
Thanks in advance…Oh and welcome onboard :smiley:

jackojackson:
What u driving Viking? Jacko :slight_smile:

The old woman daft now Jacko. :laughing: I’ve not turned a wheel in 15 years now since my accident in Ancona. When I first started on the road as a trailer boy in 1960 most of the fleet of Leylands at the place where I worked were on vacuum brakes. When I started driving in 62 my Thames Trader had vacuum brakes. :smiley:

Hope u well Viking see us modern day boys are just spoiled rotten

Jacko :smiley: :smiley:

jackojackson:
Hope u well Viking see us modern day boys are just spoiled rotten Jacko :smiley: :smiley:

And so you should be. If the boss is comfortable in his/her office, so you lads should also be comfortable.

welcome aboard,baz…i’m sure to have some questions for you. :laughing:

Shame you don’t work at Truck East at Witham, I had about 10 months of trouble with getting them to sort out the ABS on my tag axle.

I’d report it faulty, sorted they’d say. It used to trip out so often it was almost undriveable as a 6 wheeler.

Finally I got them to put new rings and sensors on and it has made a massive difference, it still occasionally faults but not very often. Flicking the ignition resets it.

Welcome to trucknet Bazabs,sure theres plenty on here need help ,from what i read.regards derek

LOOPY LOU:
Why do Daf tractor units always come up with EBS TRUCK WARNINGS?
What is the common reason for this and can it be reset without a computer?
Thanks in advance…Oh and welcome onboard :smiley:

Don’t want to hijack Bazabs thread but i do the same thing! i’ve found a quite common reason for the EBS light on DAFs is the wiring to the valve for the front axle, most commonly the offside one, if you find a break in the wiring and repair it, then the EBS light should go out once you’ve ‘run it up the road’.

Blimey i didnt know i would have this many questions so quickly,

now ill start at the top

206doorman
there are hundreds of different reasons the abs light could come on so if you ciould tell me what abs system it is you have i might be able to identify the cause more clearly, but i will say that the most common cause for the light comoing on is your wheel sensors,
while you are driving the ecu is constanlty monitoring the wheel speed signal, when the ecu sees a sudden deceleration in one or more wheels it will release the air pressure to that wheel until it sees the wheel speed signal return then if the signal then it will apply the pressure again, it the modulators that actually apply and relaese the air pressure can cycle up to 50 times a second, this is the vibrating feeling you get in the brake pedal (not so much on trucks more cars), now most ecu’s are far to fussy and any deviation in the wheel speed sinal or drop in resistance from the sensor can put the as light on, if you turn the ignition off then on and the light goes out then dont worry about it it was probably just a minor fault,

i hope this helps

loop loo

daf units with a trailer is connected the ABS truck light will be on until there is a minimum of 4.5 bar pressure in the trailer air tank, it should say trailer ABS fault but for some reason daf decided this particular fault signal from the trailer puts the truck light on,

once the air pressur is up the light should go out, if i doesnt then drive the vehicle above 10 mph and see if it goes out, if its still on then you have an active fault in the system and i would need to know what the ecu part number is so i can let you know how to blink code the system.

here is a copy of my monthly article i write in a well known truck magazine that might help.

ABS WARNING LIGHTS?

ABS and EBS warning lights!
How do you know what your warning light on your trailer or in the cab should be doing,

For starters there are only three main warning light sequences that are out there.
They are:
ON/OFF at standstill
ON and remain on until the vehicle is driven above 7kph
ON/OFF/O and remain on until the vehicle is driven above 7kph

The three main light sequences are used by knorr bremse, wabco and haldex,
with the invention of programmable warning lights in EBS systems it has become a bit harder to know what yours should be doing but with a couple of simple tests you can find out, these tests are as follows:

For trailers:
If you have an iso 7638 connector (ABS socket) on both your truck and trailer start by just connecting this and turn on the ignition, the trailer warning in the cab should come on, if the light goes ON/OFF then that is the sequence, if the light stays on then drive the truck and trailer above 7kph, if it goes out then that is your sequence, if the light stays on there is a fault in the system and you will have to fix it before you can go any further.

For trucks:
Turn on the ignition and look at the light, if it goes ON/OFF then that is the sequence, if the light stays on then drive the truck above 7kph and if the light goes out then that is the sequence, if the light stays on after you have driven off there is a fault in the system and you will have to fix it before you can go any further,

How the warning light works:

The warning light is controlled by the electronic control unit (ECU) when you turn on the ignition the ecu checks the external components to see if they are ok, after this initial test some systems will turn the warning light out and it will only come on if a fault appears when then vehicle is driven, if the warning light stays on then there is either a fault in the system or the ecu is waiting to see the wheel speed signals from the sensors, once the ecu sees signals from all the sensors it will turn the warning light out,

All ABS/EBS warning lights on all the systems have one thing in common, this is that when the vehicle is driven above 7kph the light should go out, if your light is on when you are driving you have a fault in the system.
(note: some electronic dashboards don’t show a warning light until a fault appears)

this is this months article about iso7638 sockets ( ABS sockets)

ISO 7638

Yet again this week I have done several jobs where ive been asked the same question over and over again, how does the ABS lead work?
Everyone seems to have there own ideas how it works ranging from if it’s not plugged in your trailer brakes wont work to it’s only a back up power anyway!! Both wrong!

The truth is the ABS lead or iso 7638 as it is actually called is essential to make your trailer ABS work correctly,
and if you have the connections on your truck and trailer they must be connected and must be working correctly,
this also means the ABS light you should be looking at is in the cab and not the one on the trailer headboard.

This is where the problems start, how does the ABS lead actually work, well this is how:
Pin 1 in most trucks is permanent live
Pin 2 is switched ignition live
Pin 3 is common return to battery negative
Pin 4 is common return to battery negative

And most importantly and the most misunderstood is
Pin 5 which is the warning light control wire,
Some people think pin 5 is controlled by the trucks ABS system or even by the truck itself, both of these are wrong, how it actually works is quite simple, a basic way of explaining it is this:

Power from the battery via the ignition switch goes to a fuse then to the warning light in the cab then to pin 5, when you connect your ABS lead to the trailer the trailer ABS system sees 24 volts coming down pin 5 and then lowers that voltage inside the trailer ecu to below 5 volts which then brings the ABS light on in the cab, when you drive away and the trailer ABS system is happy with the wheel speed signals the ecu then raises the voltage back up to 24 volts and the warning light in the cab goes out, then if a fault appears when you are driving the ecu lowers the voltage again bringing the light back on,(this is only a basic description of the warning light circuit).

An easy way to check the power from the iso socket is to Get a multimeter and test between:
Pin 1 & 4
Pin 2 & 3
Pin 4 & 5
You should have 3 lives and two earths.
Or you could use an iso tester (see pic) which will do all these tests for you, just plug the iso tester into the truck and look at the LED display on the side.

Most new trucks don’t actually have a warning light as such, Instead the dash is an LCD display which shows a picture of a trailer or trailer warning but pin 5 still works the same way,
It’s always controlled by the trailer ecu.

The next thing to mention is pin 6 and 7 in an EBS lead, these are the “CAN” connections “CAN” means control area network which in simple terms is a connection between two or more ecu’s allowing them to talk to each other,
when you have a EBS truck and a EBS trailer the braking is done through the “CAN” lines, basically when you press the brake the truck sends a “CAN” signal to the trailer ecu to tell the brakes to apply, if the “CAN” signal fails the brakes will still work via the air pressure signal through the service line.
Some people have said to me that If you have a ABS truck and EBS trailer then the trailer brakes wont work properly, this is not the case, all it means is the truck cant send the “CAN” signal to the trailer, the brakes work as normal.

And the last thing to remember is when you’re driving the ABS light should be out.

:smiley: Cheers for all the great info Baz but in relation to the Ebs truck warning on dafs i was talking about this light being on with no trl connected. Any more ideas would be good.