A fault finding test gives you a system, tells you what went in and what came out, and asks you to work out where it went wrong. This guide walks through the logic with a generic example, explains what candidates mean when they search for a driver fault finding test, and sets out how employers can read the results sensibly.

What a fault finding test asks you to do

Troubleshooting is one of the most common problem-solving tasks in technical work. Jonassen and Hung describe it as diagnosing why a system is not working and then repairing it, and argue that good troubleshooters combine knowledge of how the system works with a disciplined way of testing hypotheses [1]. A fault finding test isolates the reasoning part of that skill, so that it can be measured without specialist equipment or prior technical training.

The Viewpoint fault finding test has 25 questions to complete in 20 minutes. In each one you see a sequence of switches. You know what each switch is supposed to do, you are shown the input and the output, and you work out which switch in the sequence is faulty. That makes it relevant to maintenance, engineering and control-room roles where problems must be located logically rather than by trial and error.

A walkthrough: tracing a fault through a chain of switches

The example below is a generic illustration written for this article. It is not a Viewpoint item and does not use the same symbols or rules.

Imagine three letters, A, B and C, entering a system from the left. They pass through three switches in turn. Switch 1 is meant to reverse the order of the letters. Switch 2 is meant to swap the first two letters. Switch 3 is meant to swap the last two. You are told one switch is not working, meaning it lets the letters through unchanged.

If everything worked, the letters would go from A B C to C B A after switch 1, to B C A after switch 2, and to B A C after switch 3. Suppose the output you are shown is C A B. Which switch failed?

Test each hypothesis in turn. If switch 1 failed, the letters stay A B C, become B A C after switch 2 and B C A after switch 3. That does not match. If switch 2 failed, the letters become C B A, stay C B A, then become C A B. That matches. A quick check on switch 3 gives B C A, which does not. The faulty switch is switch 2.

The method generalises: work out the expected state after each step, then ask which single failure explains the output. Schaafstal, Schraagen and van Berlo found that technicians trained in this kind of structured troubleshooting, combining a general strategy with a clear functional picture of the system, solved twice as many malfunctions in less time than those trained in the traditional way [2].

"Driver fault finding test": what candidates usually mean

Searches for a driver fault finding test usually come from people applying for driving roles, most often trainee train driver posts, who have heard that the assessment includes reasoning or checking tasks. In Great Britain, the Train Driving Licences and Certificates Regulations 2010 set the minimum content of the examinations before appointment. Alongside medical checks, these list cognitive areas such as attention and concentration, memory, perception and reasoning, and require an occupational psychological examination to confirm the candidate has no occupational psychological deficiencies relevant to safe driving [3].

The regulations do not name a fault finding test, and different employers use different combinations of assessments. If you are a candidate, ask the recruiter which tests you will sit. If you are an employer, a fault finding test can contribute evidence on logical reasoning for technical and operational roles, alongside measures such as a concentration test and a train driver situational judgement test.

Strategies and interpreting results

For candidates, three habits help. Write down the expected state after each switch rather than holding it all in your head. Test one hypothesis at a time. And keep an eye on the clock: with 20 minutes for 25 questions you have under a minute each on average, so move on from a stubborn item and return if time allows.

For employers, read scores in bands from Very Low to Very High, not against a single pass mark, and combine them with other evidence, such as a structured interview about a time the candidate diagnosed a problem, or a mechanical comprehension test where the role also needs an understanding of physical principles. More detail on the format is on the fault finding test page.

Frequently asked questions

Do I need technical knowledge to take a fault finding test?

Generally not. Fault finding tests of this type explain how the system is meant to work, and they focus on logical reasoning about it rather than knowledge of electronics or mechanics. Read the instructions carefully before you start.

How long does the Viewpoint fault finding test take?

It has 25 questions with a 20-minute time limit.

Is a fault finding test the same as a mechanical comprehension test?

No. Mechanical comprehension tests ask about physical principles such as levers and gears. Fault finding tests ask you to trace a logical sequence and locate where it breaks.

Is a fault finding test required for train driver selection?

The regulations specify areas to be assessed, such as attention, memory, perception and reasoning, rather than particular tests. Check with the employer which assessments they use.

References

1. Jonassen, D. H. & Hung, W. (2006). Learning to troubleshoot: a new theory-based design architecture. Educational Psychology Review, 18, 77–114.
2. Schaafstal, A., Schraagen, J. M. & van Berlo, M. (2000). Cognitive task analysis and innovation of training: the case of structured troubleshooting. Human Factors, 42(1), 75–86.
3. The Train Driving Licences and Certificates Regulations 2010 (SI 2010/724), Schedule 1, paragraph 2. legislation.gov.uk.