Semi-Trailer Braking Inconsistency with EBS: Possible Europa Valve, Sensor, or Electrical Issues

Hello forum users
The problem is related to poor brakes in the semi-trailer, more precisely, the semi-trailer brakes once as it should, whether it is empty or full, and then it brakes poorly. The trailer has EBS and is pulled by a Volvo FH12 Chinese. After disconnecting the EBS cable, the trailer brakes well, although the braking force is not evenly distributed over the 3 axles due to the different degree of wear of the linings. Does this mean that the so-called europa valve is ok? Could it possibly be the fault of the sensor in the trailer's valve? When starting the tractor, an error in communication with the CAN bus of the trailer does not always pop up, though often, so maybe it is an electrical fault and hence the variability of the trailer braking, or maybe something else? I know that I have to check it, but I wanted to ask what else should I check if I already have a trailer in the workshop?

1. Disconnecting the EBS cable results in no adjustment of the braking force.
2. Uneven lining wear (I understand that we are talking about drum brakes) rather suggests a fault in the actuator itself (actuator, "ratchet", expander).
3. I would also check the tractor, specifically the trailer brake control valve.
4. It does not hurt to perform EBS diagnostics of the trailer (if only with good equipment).

1. That's right, after disconnecting the EBS cable, the trailer brakes practically 1: 1
2. I meant that after unfastening the EBS cable, the first axle reacts the fastest during braking, i.e. it brakes the most, and the second and third with a little less force, which makes the axle empty with the first axle lowered during braking, this axle practically brakes by burning rubber. Of course, drum brakes. I rather exclude the executive system, no play, everything stiff, works properly.
3. How can I check the mentioned valve?
Is it possible to somehow check the valve of the trailer, and more specifically the sensor that is in it? Is it removable?
If, for example, the trailer brake controller in the tractor was to blame, would an error be displayed or the computer not necessarily informing about it?

The EBS of the trailer is regulated by the brake ONLY left - right side. There is no adjustment to individual wheels. If the first axis responds faster, the wrong actuators may be installed. It would be good to measure the braking forces on the "rollers".
As for checking the trailer control valve, you should connect the car to the computer and check, first of all, whether the pressure at the outlet of the valve corresponds to the information sent via CAN. And whether the results are similar each time.
I do not know what EBS you have in the trailer (manufacturer), and this information is also worth providing.

It looks like there is no need to do without diagnostics. Symptoms may indicate damaged cable connections between the car and the trailer. If possible, replace the Ebs cable of the trailer. You also do not write which year the car is from, it is important because in the new vehicle models with the new ebs systems it is possible for the tractor to read information from the valve about errors and the cooperation between these systems has been extended to improve braking performance.

gumbal3000 wrote:

Quote:

however, the braking force is not evenly distributed among the 3 axles due to the different degree of lining wear

The thickness of the pads has no effect on the braking force.

It is always the case that drivers feel the brake force fluctuating when there is a problem with the EBS system. The dependence is that if the EBS is lit in the semi-trailer, the empty semi-trailer brakes sharply and sharply and the semi-trailer pushes fully and the driver feels that it brakes less, it is the effect of a delayed reaction resulting from pneumo-mechanical braking systems. The efficient EBS system uses information that shortens the reaction time and properly selects the force needed to brake the vehicle.

As for the EBS manufacturer, I will check and let you know because I'm not sure. The tractor is from 2004. In the near future I will try to replace the EBS cable, if it does not help, I will probably have to go to the computer. In my case, the brakes "stupid" and both empty and full, ie empty sometimes you feel that the set brakes nicely, the horse and the trailer are in harmony, and when braking the next time it feels like the trailer is not braking at all and it is exactly the same as full. Sometimes, for example, 10 brakes are all, then the trailer brakes poorly for a few brakes, and this is how it is done, there is no rule. So let me start with the simplest things, i.e. replacing the EBS cable, the set previously had a rather long break, so maybe the cable lost its flexibility. Previously, I had a similar situation with the pneumatic conduit, which began to let air on the bend, and with the conduit from the lights, where one turn signal and reverse lights sometimes lost.

Pay attention to the number of pins in the plug because abs has 5 pins and ebs has 7 pins. There are no two contacts in the 5-pin because there are no can cables.

stanisławpiotr wrote:

It is always the case that drivers feel the brake force fluctuating when there is a problem with the EBS system. The dependence is that if the EBS is lit in the semi-trailer, the empty semi-trailer brakes sharply and sharply and the semi-trailer pushes fully and the driver feels that it brakes less, it is the effect of a delayed reaction resulting from pneumo-mechanical braking systems. The efficient EBS system uses information that shortens the reaction time and properly selects the force needed to brake the vehicle.

xxxx Lighting of the trailer ABS indicator light does not always change the braking force. It is enough to unplug the plug from the COLAS valve and the ABS indicator will light up because there is no other way to signal the fault on the trailer. The brake force will change in two cases:
1. The EBS controller does not get the correct power. At this point, we have 1: 1 braking, which means that the trailer will brake with full force.
2. Damaged bellows pressure sensor or spring deflection sensor. Then the controller receives incorrect information about the weight of the vehicle and may not properly adjust the braking force.

Added after 5 [minutes]:

stanisławpiotr wrote:

Pay attention to the number of pins in the plug because abs has 5 pins and ebs has 7 pins. There are no two contacts in the 5-pin because there are no can cables.

And what does this have to do with it? How is this supposed to help rectify the fault?

According to what gumbal3000 writes, I would bet on the problem with the horse, which I wrote about earlier.

Moderated By CameR:

I removed the malicious remarks.
Reg. 3.1.9. Do not be ironic and do not be malicious towards the other side of the discussion. Please respect dissenting opinions and other opinions in the forum.

You can see that a colleague cut his teeth on TEBS systems, he makes fun of his colleagues' knowledge and experience, although he has gaps on this topic himself. Thanks to the CAN cables, the TEBS system owes its speed to operation, therefore I paid attention to the efficiency of the car-trailer connection cable. As the colleague of the previous speaker mentioned it and the power supply with this cable is supplied to the trailer and its damage is caused by the mentioned problems with braking. One colleague did not mention that the TEBS system is also powered by brake lights and damage to the ECU power cable does not completely disable control over the braking system. And one more thing, not only the problems that you mentioned, cause the tebs to be turned off, because it often happens that there are no electrical faults and the system turns off, e.g. a bad signal from the wheel speed sensor.

When it comes to power supply from brake lights, not all manufacturers of trailers / trailers use them (Schmitz, Krone - yes, Wielton-option, Koegel-option). I don't make fun of anyone. However, I do not agree with the statement that an incorrect signal from the ABS sensors will disable the brake force regulation (ALB). The ABS will then turn off and the stability system (if any) will turn off and the ABS indicator will turn on. As for the braking signal sent via the CAN line, honestly, I have not yet met a driver who would be able to find out about the difference in braking time (with or without CAN). The difference in reaction time is minimal, although there is a difference in the distance with hard braking.
Well, it's not time for lectures.

If anyone felt offended by my statements, I am sorry.

I think now is the time for information from the interested person himself

Thank you, gentlemen, for your interest, unfortunately due to lack of time, I have not taken up the topic of repair yet. Earlier, someone asked what company the valve in the trailer is: it is Wabco.
As for the cable, it is a 7-pin cable.
I do not know if I wrote about it before, but no ABS indicator light is on, only sometimes when starting it shows an error regarding the communication of the EBS systems of the trailer.
Of course, in my free time, I have to check the cable that someone mentioned first.
I have one more observation:
When the car is started and there is no EBS error message and when I disconnect the EBS cable, the computer in the horse will immediately report it. However, when the EBS connection fails while the horse is running and I disconnect the cable, the computer does not inform about anything as if the connection was simply not there. I don't know if this is important or not, or if it could indicate damage to the cable or the horse driver. Of course, in his free time he will "scan" the cable with the meter.

My friend, there are many reasons for a disco with EBS braking power: from a simple drop in power supply to things that you never dreamed of, i.e. those that require unimaginably a lot of knowledge, skills and all. The previous speakers described perhaps a few percent of the possibilities in the head, sometimes overlapping two or three on each other, or resulting from one another, without going into detail. Therefore, you should now decide whether it is a common or annoying fault with these symptoms. How to do it, just basic pressure measurements and some spare time to make tips.

Hello after a long absence. Thanks to everyone for the answers and hints. The problem is solved, luckily the ebs cable was the culprit. In the plug that is plugged into the semi-trailer, the 2 pins were quite green, the rest of the pins were quite cramped with some black greasy dirt, which disturbed the voltage transition quite strongly, even during the test with the meter, you had to scratch the tip quite strongly to make the transition. After replacing the cable, everything is ok.

The trailer plug works more and is faster on this side. When it enters quite tight, it contacts you. How to feel that it enters clearly loosely, this is a guaranteed problem. Dirt, muck, corrosion is not a problem. A loose plug is a problem. Pissing with contacts for a few days may help, but in the long run it gets even worse. Some semi-trailers, e.g. on Haldex, save themselves in such situations by powering the brake light, which makes it difficult to understand what is happening.

As you write, the plug from the side of the trailer additionally "entered" quite loosely + dirt about which I wrote. From the side of the horse it goes tight and the pins are very clean. It's good that it was the cause, and not something more serious - much more expensive.