Car Data & News | Car Data Introduction
Updates
We continually publish new information in our regular newsletters and,approximately six times a year, distribute all the up-to-date data to CarData members.
Information comes from towbar fitters.
Most of the information contained in the CarData report comes from our customers. We collect and collate it. Sometimes we devise new products to solve problems customers have alerted us to. Sometimes we work together to find the best ways to overcome fitting problems. Benefit from sharing and exchanging.
The free exchange of information helps everyone. When towbar fitters share information about new cars they all benefit and so do their customers. We compile the most comprehensive possible record of car data and to make it freely available to the trade.
Car Data Record
The Car Data Record form in this section is designed to collect and store information about the cars you fit and problems and solutions relating to them.
Send a copy to us
When participating fitters come across new models or problems, they fill in the form to keep for future reference and send a copy to us.We then use it to update the CarData file.
Disclaimer
By passing on information collected in the Car Data report Ryder Towing
Equipment Ltd does not assume responsibility for its accuracy. We are simply
passing on data collected in good faith from contributing towbar fitters. It is always
the responsibility of the individual fitter to ascertain the conditions that apply in any
vehicle he or she is working on and to complete his or her installation accordingly.
This information is not published for the use of non-professional fitters of towbar
electrical equipment.
Perform essential checks
Cars are changing all the time, often in subtle ways that you may not notice but which may have important implications for you. So always perform your essential checks, including:
1. The vehicle
Wire thickness and current capacity (See page 3: of the products section for a cable capacity chart.)
Fuse ratings
Circuits sharing critical fuses
Bulb-failure detection (Remove a brake light and side light bulb and run the engine. See if a fault is displayed.)
Computer-controlled systems
2. Your installation.
How much current will your installation draw?
Is it possible that the trailer to be towed will draw more current than you might usually expect (extra brake, side, flasher lights, etc.)?
Will you protect vulnerable circuits in the vehicle?
Do you have the correct components?
Are the components you intend to fit suitable for the purpose?
Bulb-failure Warning Systems
Bypass Relays
Bypass relays were first developed and introduced by Ryder Towing Equipment Ltd. Since their introduction, other manufacturers have broadly copied the Ryder designs, Bypass relays allow trouble-free fitting on vehicles with complex electrics and electronics. They are designed to operate trailer road lamps in unison with the towing vehicle’s road lamps without drawing any significant current from the vehicle’s road lamp circuits.
Not detected
Bypass relays employ miniature relays to switch the trailer lamps on and off. Connection is made to the vehicle’s lamp circuits but only for the purpose of energising the coils of the relays. The current drawn by each relay is less than 40 milliamps (0.04amps). This current is so small that it can be drawn from the vehicle’s lamp circuits without bulb-failure warning devices in the vehicle detecting its loss because the normal tolerances found in typical vehicle lighting circuits are greater than 0.04 amps.
Power direct from the battery
Power for the trailer lamps is taken directly from the vehicle’s battery and merely switched by these relays. No significant load is put on the vehicle’s own lamp circuits.
Easily handle currents
Although the coil currents are tiny, the switching capacity of each relay is 10 amps. This means they can easily handle the currents found in typical trailer/caravan road light systems.
Bypass Relays available from Ryder Towing Equipment Ltd.
| TF1011 | Single |
| TF1013 | Three way |
| TF1014 | Four way |
| TF2217 | Seven way with flasher monitoring |
| TF2217U | Smart seven way for the most complex fittings |
| TF110R | Two way with flasher monitoring (Flasher booster) |
Computers and Multiplex Wiring Systems
Multiplexing is a method of transferring many data signals along a single "bus"cable to switch relays drawing their power from a single power cable. Using this method, many devices can be controlled without a mass of individual interconnecting wires. Multiplexing is associated with computer control units, these being the source of the control signals.
How will the use of computers and multiplexing affect the towbar fitter?
There is some concern in the industry that the introduction of these systems will drive towbar fitting into the workshops of vehicle main dealers and away from the specialist fitter. These concerns centre around the provision by some manufacturers such as Volvo for computer downloads associated with the fitting of manufacturers' towing kits, engine management and on-board diagnostics.
The questions are:
Will computer downloads modify engine management systems to accommodate towing and thus be essential?
- Will the addition of towbar electrical systems that are not supplied by the manufacturer cause problems for any diagnostic systems installed in the vehicle.
- Will even the fitting of bypass relays fail to prevent malfunctions and alarms caused by the towbar electrical installation
The answers are:
No: Engine management systems are carefully set up to cope with all likely conditions and will already handle towing. There is no likelihood, at least in the foreseeable future, that it would ever be appropriate for manufacturers would introduce downloads for towing, related to the management of engine performance. Such downloads as exist perform much more humble tasks such as the commissioning of the fog cut-out system.
No: On-board diagnostic systems are designed to take into account the normal conditions that apply in a vehicle. These include a lighting system that has bulbs. Bulbs are variable. The resistances found in different bulbs of the same type and wattage will vary considerably. In determining what is normal, any OBD system has to take into account these possible variations. They do this by being set up to respond to fairly large variances, outside defined ranges. If towbar electrical systems create variances that do not stray out of these ranges, they will, effectively, be invisible to OBD systems.
Even without bypass relays, direct towbar electrical connections should be invisible to on-board diagnostics at the time these are used. Since, presumably, no trailer is present during diagnosis and servicing to provide loads on the towing electrical circuits, these circuits, unless they are faulty, will be "invisible". Such connections might make problems during towing but should not do so during diagnosis and servicing.
and
No: Provided that bypass relays are correctly installed, their electromagnetic coils do not draw sufficient current to be detectable by monitoring systems in vehicles or to add significantly to the load on the individual circuits to which their signal wires are attached.
The rules for correct installation have not changed:
If bypass relays are not installed, any loads generated by the trailer lights will fall directly onto the vehicle's systems. Monitoring systems will be alerted if they are in place. Circuit overloads can also be created by such direct connection.
- If the vehicle has conventional feed wires leading to the light units or clusters and these wires supply 12+ volts and sufficient current to drive the lamps, the coil signal wires of bypass relays can safely be attached to these feed wires.
- Connect the bypass relay coil signal wires to the appropriate vehicle light feed wire
- Connect the relay's power input terminal to the battery, using a suitable gauge of wire and fusing it appropriately, close to the battery.
Basic Principles
The multiplex system used on vehicles has a large supply cable running around the vehicle. Connected to this are electrical system units i.e. relays, lamps, actuators, motors and other electrical equipment. By transmitting a coded digital signal, either electrical or optical around a second cable known as a data line or "bus", the electrical system units can be made to operate.
Fitted to each consumer unit is a decoder, which recognises when a given signal is being transmitted along the data bus. On receipt of the message by the decoder following the recognition of its call-up code, a relay is operated by the decoder as instructed and thus the consumer unit is actuated. One data bus can carry a number of messages: this is done by allocating a time slot for each instruction. The process for dividing the time is known as time division multiplexing (MUX).
Since each burst of data is sent many times a second, the response of the system appears to be instantaneous as far as the driver is concerned, just as if the switches were wired directly to the electrical system units.
A practical multiplex system would incorporate many sending
and receiving units, located at strategic points around the
vehicle, all connected to the same data bus.
Because the signal current needed to operate a multiplex system
is very low (10 mA) good connections are important. Furthermore,
precautions must be taken to reduce electrical noise (interference)
in the line, since this can interfere with the digital signals
in a manner that would affect the operation of the system.
Fibre optic cables are unaffected by electrical fields especially those radiated from HT ignition systems.
The additional cost of multiplex systems, along with design conservatism, has meant that relatively few systems have reached the market and multiplexing has tended to be confined to just part of electrical system such as door sub harnesses. This situation appears to be changing, with many manufacturers introducing multiplexing elements into an increasing range of models.
Advantages of multiplexing
Wiring harnesses are small and simpler providing a saving on cost and weight.
- Faster harness installation time.
- Reliability through the reduction in the number of wires being used.
Self-diagnosis can be built into the system. Detecting multiplex systems
Tell-tale signs are not obvious but multiplex junction boxes typically have few (e.g.three) wires going in, including at least one thick one, and many coming out to feed the various devices. Experience tell that identifying multiplexing is not at all simple. Some vehicles have junction boxes with large numbers of wires coming out in all directions. The Honda Accord has partial multiplexing which is virtually undetectable, despite being quite critical to towbar fitters.
Can you tap into the multiplex feed wire?
There will be a thick power feed wire associated with any multiplex system. It is unwise to tap into this feed wire as a source of power for bypass relays, because of the likelihood of interfering with the multiplex signalling and this fact should be taken into account by any fitter looking for a suitable power source other than the battery.