When it comes to trailer EBS fault diagnosis, the first step is to know which trailer ECU you are dealing with. Knorr- Bremse’s Carl Dibble has some useful tips.
Knorr-Bremse introduced its second generation of Trailer EBS, TEBS G2, in 2008, and subsequently released TEBS G2.1 & TEBS G2.2. While this latest generation has the same basic EBS functions as the original first generation of trailer EBS TEBS4, there are differences between TEBS4 & TEBS G2, and also between each of the TEBS G2 versions that technicians need to be aware of.
1. Different modes of brake pressure at standstill.
2. Pin code for the ECUTalk Software
3. Difference between the TEBS G2 versions
■ TEBSG2.0 utilisest he park shunt valve with integrated emergency feature.
■ TEBSG2.1 & TEBSG2.2 have a built-in emergency feature and utilise a standard park shunt valve. The emergency feature is visible by the silver valve on the front of the ECU, shown in Fig1. Note: this valve is not serviceable and should not be removed.
■ TEBSG2.0 & G2.1 have the older style round sensor extension cable connection. TEBS G2.2 has the newer square style sensor extension cable connection. (see above image)
The G2 ECU’s are not compatible with each other and only the correct aftermarket replacement ECU should be fitted.
4. Easier ECU ID
To assist with identifying the aftermarket ECU’s Knorr-Bremse has launched silver top ECU’s which indicate that they are intended for the independent aftermarket only see Fig 2a & 2b. The company says it is important to ensure you only fit a silver top ECU for spares, otherwise you will not be able to program the ECU.
5. Type approval
UK trailers are now subject to type approval. This means that significant changes to the design of the trailer, is not permitted without the necessary paperwork and authorisation. This includes alterations to the brake performance and any stability control functions enabled, through re- programming of the ECU.
6. Identifying trailer ABS faults
Often trailer ABS problems are caused by the towing vehicle. If there is insufficient power supply from the truck, for example, then the trailer warning light will illuminate.
So, it’s always worth trying a different truck with the trailer before defecting it.
If your trailer is under manufacturer’s warranty then they should be contacted in the first instance. For older trailers an approved service centre can help. Alternatively, the Knorr-Bremse ECUTalk Software for Trailer is available to purchase from an authorised distributor.
7. More help
The Knorr-Bremse website www.knorr-bremsecvs.com has detailed product explanations along with service and repair information, which Knorr-Bremse has made available. Also a quick call or email to the Knorr-Bremse technical team can often save time and money if you’re not sure exactly how a product should be performing. Software and documentation can also be downloaded from the site.