Faults that even the repairers don't like
Unfortunately, there are also occasional problems on vehicles that mechanics don't like and don't enjoy a bit. The reason is simple – it is not possible to diagnose quickly and unambiguously what needs to be replaced or repaired. These issues are both mechanical and electrical and we will try to describe some of them.
Problems with the vehicle's electrical and electronics system are often indicated by a violent reaction of the various warning signals on the instrument panel. This can scare you as a driver and direct you to the workshop by the shortest route. Even if there is no strange behaviour or missing functions, the alarms still warn you that something is wrong. These alarms are certainly not without reason. Their role is to prevent major damage and problems, especially if the defect could affect driving safety. But it's usually the case that when you arrive at the workshop, there are no clear signs of what's wrong at first glance. Diagnostics is crucial in such cases because it detects faults and reports from several different vehicle systems. And here begins the issue that mechanics don't like.
The thing is, the protocols in the car have long been ambiguous. For example, when we turn on the lights, the wipers or the fan, we don't actually do it via a switch. This command is only transmitted via the vehicle's communication network (CAM–BUS) to a specific processor, which only then actually activates the switch.
85% of electrical faults are problems with wires and contacts
For this reason, during an interruption, even if only temporary, alarms signal faults in this communication between systems. Situation: I've come to the dentist and my tooth doesn't hurt anymore. So, at the moment, it seems to be a search for a needle in a haystack. The time spent on diagnostics is significant and difficult to account for. In the meantime, several other interventions could have been made that would have brought much better profits to the workshop. On the other hand, workshops that are about "chasing the unknown" invest in what is most valuable – fostering your own knowledge and confidence. These are the workshops you'll come back to again and again!
Therefore, it is crucial that such things are not solved by rote or by a system of elimination. If we use technical documentation and electrical diagrams of the vehicle, with knowledge of the principles and modes of operation of the systems, then finding the source of the problem is much quicker.
Statistics show that 85% of electrical faults in cars are related to problems with the connection or wiring itself. If working by rote, the mechanic may end up angry with himself because after a long time he finds it difficult to charge for rejoining a broken wire or a contact in a connector. Therefore, only by checking and using the documentation can we avoid unnecessary time wasting or component replacement, which will not solve the problem but may increase the repair costs.
Good attention to drive and suspension
Mechanics also have their own mysterious faults that are difficult to detect. The vast majority of them are related to strange noises coming from the engine, chassis or some other part of the vehicle. Of course, when the vehicle is stationary or on a lift, where the suspension is released and the elements change position, it's hard to say where the problem is coming from. Often, even after a test drive, we are not sure where the sound is coming from. Replacing parts that are questionable often does not produce results and therefore increases the repair time. Therefore, a thorough triage should be done to determine whether the sounds are coming from the suspension or the drive – this is the starting point.
If necessary, it's better to put the car on a shock absorber tester, for example, and monitor the effect of vibrations and sounds, rather than spend hours torturing yourself. Test driving in a safe place, over hills and valleys, or with a load change will help to channel the problem. Also, any observations the driver makes – sounds when the vehicle is cold or warm, when accelerating or braking, on bumps, when turning – all contribute to a quicker diagnosis. However, most of the sounds that are harder to detect originate from the suspension due to the wear of some of the spherical elements or rubber-metal joints. It is therefore always a good idea to replace them on both sides, as well as the adjacent elements they are tied to (e.g. beads, almonds and forks), as they are also no longer in perfect condition. Thus, future sounds are also solved in the same way.
It sounds good as long as you're driving, but not always. When you stop – silence
Engine sounds are often much more intense and do not depend on road conditions or changes in direction. They need to be listened to carefully. They can also be heard in the workshop, especially if they come from certain rolling elements – belt bearings, chain guide, etc. Sounds can also originate from the gearbox and most often disappear at standstill. The jolts can also be clutch related, but also due to a weakened motor mount, which gives the motor a higher tolerance. Anyway, problems like this take time and you need to analyse the sounds well so you wouldn't waste time changing parts. Often the part replaced is small and cheap, but the new relationship between mechanic and driver is worth more. It is also important to remember that fixing these problems in time prevents more damage and costs, as often mysterious noises are just a sign of bigger problems.
This article was published in Bartog INFO No. 4, Autumn/Winter 2022/23.