Auto Electrical

Auto Electrical 

Given the conditions under which off-road vehicles operate, it is perhaps not surprising that auto electrical issues and break downs are the most commonly occurring problems after overheating, particularly in Southern Africa, where the combination of extreme heat, vibration, dust, sand and water can cause havoc in 4WD vehicles’ electrical systems.

Compounding the problem is the fact that auto electrical systems on new 4WD vehicles have become enormously complicated: new 4WD vehicles (excluding SUV’s, because they are “soft roaders”, and do not count as proper 4×4’s) can have upwards of 20 sensors on the engine, suspension, brakes, transmission, steering, transfer case, and differentials all of which are controlled by control modules, which are in their turn controlled by an ECU, or Electronic Control Unit, aka Engine Control Unit. In addition to all this, the individual wires that make up the wiring harness are not as heavy or thick as they used to be: the thin wires in modern 4WD vehicles have virtually no overloading tolerance and the slightest problem could cause them to burn and fuse together, with usually very expensive results.4x4 Auto Electrical System - Fault finding

Then there is the problem of connections: try as they might, 4×4 vehicle manufacturers have yet to come up with absolutely water- and dust proof connectors, and given the fact that the average number of electrical connections on a new 4WD vehicle can count in the hundreds, the harsh off-road conditions in Africa have been known to cause irreparable damage to auto electrical systems., Despite all of this however, modern auto electrical systems are far more reliable than they have ever been in the past, but this reliability comes at the price of owners and drivers generally not being able to repair auto electrical issues on a DIY basis.

Fault finding and diagnoses on new off-road vehicles can only be done with diagnostic computers and even supposing that one was available to trace an auto electrical problem on a 4×4 vehicle in the middle of Somalia, the sheer number of possible causes, not to mention the number of spare parts that need to be carried to repair even the most common faults, could mean that the vehicle can not be repaired since the replacement of some control modules require the ECU to be reprogrammed, with software that is not readily available to the general 4×4 enthusiast, regardless of whether he is stuck in Somalia or just the Richtersveld in South Africa.

Nonetheless, none of the above issues should prevent anyone from undertaking a Cape to Cairo trip through Africa just because some electrical component might fail: many hundreds of thousands of trouble free off-road kms are travelled in Southern Africa each year. All that is required is the same degree of faith that nothing will blow up, fuse, burn out, short circuit, and/or drop off as is placed in the fact that the sun will rise every day- and some basic preventative maintenance of course.

It would be a big mistake to assume that since a 4WD vehicle is new, it is free of auto electrical defects, especially if the 4WD vehicle is going to be used for anything more than a Saturday Morning Trail along the Hennops River in South Africa. Sloppy assembly and misrouted wiring are common problems on all vehicles, 4WD vehicles included, and everyone contemplating a long off-road excursion would be well advised to follow the short checklist below to make sure they do not run into unexpected auto electrical problems in the hinterland of Africa.

While this article is only a short overview of what to look out for, other, more specific auto electrical issues will be addressed in follow-up articles, which is not say that the information here should be disregarded: far from it: it is pertinent, germane to the issue, and it could save an expensive and well planned expedition from being delayed or even cancelled. So, with that in mind, below are some pointers and things to consider:

A Comprehensive Diagnostic Check

Not all 4WD vehicles have on board diagnostic systems of course, but a full and comprehensive auto electrical test is required on those that do have a diagnostic feature, even if the vehicle is brand new. It is common for dealers to cancel all warning lights when vehicles are delivered to them, (not saying anything about it to an unsuspecting buyer, of course), however, all fault data, if any, is stored in the ECU and can be retrieved with good diagnostic computers- if they are used by mechanics who can interpret the data.

Some diagnostic computers are better than others and while some may only be able to retrieve stored fault data, others have the ability to test most, if not all, auto electrical systems and sub-systems. With the engine running, some programs can measure injection timing and duration on mono rail diesel engines, the efficiency of the sensors that measure and control intake air on petrol engines, ignition and timing mapping on petrol engines, turbo boost, oil pressure and temperature, coolant temperature, and other critical systems and parameters. However, more importantly, a full auto electrical diagnostic check will reveal any incipient issues, and while it may not pinpoint the exact source of the problem, it will highlight any issues that need attention, such as the alternator for instance.


A simple multi-meter test may show an alternator to deliver the correct voltage, but it will not reveal the wave form of the output current. While a slightly defective alternator may function for an extended period, a good diagnostic computer will reveal the state of the six diodes that convert the Alternating Current developed by the alternator into Direct Current. The form of the electrical wave is directly relatable to the efficiency and correctness of the windings, as well as the rectification process, and while very slight deviations from the accepted norm may not be stored as fault data by the diagnostic system, a visibly defective wave form is a clear and definitive indication that the alternator is defective and must be replaced- before the start of a Cape to Cairo tour through Africa.


Even a slightly defective alternator will eventually damage a battery, and while most diagnostic systems will store battery related fault data, these systems are notoriously vague on the cause of the problem. Batteries may lose power for dozens of reasons, ranging from being defective to a current draw from any of hundreds of connections, to tracking devices that draw more current than is commonly realised. Because of the number of unknowns, there is little point in performing current draw investigations with the battery connected to the system.
All batteries should first be removed from the vehicle and have the relevant tests performed on them while they are disconnected. If the battery is sound, each system and sub-system must be isolated and tested by itself, which is a difficult and time consuming process, not to mention the fact that independent workshops are often much better at this sort of examination than authorised dealers. The reasons for this are many and varied but the fact remains that dealers are often reluctant to undertake this type of auto electrical work, especially under guarantee conditions: they often just replace a couple of “little black boxes” and call the auto electrical issue resolved, which is not good enough from the off-road driving perspective. A proficient and competent auto electrician armed with a good diagnostic computer will test the voltage AND the amperage in all auto electrical systems, as well as leakages to earth, which is the only way to find and fix a current draw problem.

General wiring

Wiring issues on new 4WD vehicles are notoriously difficult to find and repair, but a new 4WD vehicle with no stored fault data can generally be taken to be free of wiring and other auto electrical problems, at least until one presents itself, but that may never happen.

However, the wiring of all 4WD vehicles, whether new or used, that are fitted with electrical accessories must be thoroughly checked for potential problems. Some types of after-market driving lights for instance, are very large electrical consumers and their installation often leaves much to be desired. Even dealer-fitted driving lights are sometimes not protected by dedicated fuses and relays, and wiring is often just twisted together, not soldered or spliced into the harness in a safe and/or prescribed manner. Bad connections on heavy consumers cause arcing, which can lead to major failures of the auto electrical system, not to mention fires that have been known to destroy even new 4WD vehicles.

Auxiliary batteries and their cabling to winches and ice-boxes are another common problem area: earth straps are often just thick wire, while positive power cables are more often than not of the correct amperage rating. Worse, positive cables are often of the wrong type, with incorrect conductors that could cause excessive resistance, heat build-up, alternator failures, and possible fires as a result.

Auxiliary battery isolators are often cheap, substandard, and placed in positions where they are difficult to reach in an emergency: while an isolator should be within easy reach, it should also be placed away from possible impacts, contact with water or fuel, and it should not arc when it is operated. A good way to test an isolator for arcing is to operate it in the dark; any sign of arcing is an indication that it is either a substandard unit, or defective. Replacement is the only remedy in these cases, with a possibly fatal fire the result if it is not.

A Safe Auto Electrical System?

Given their operating conditions, especially in Southern Africa, the electrical systems on older, used 4WD vehicles are much more likely to be troublesome than that of a new off-road vehicle. However, older auto electrical systems are much simpler, which makes their maintenance and repair possible for the average 4×4 enthusiast, without having to rely on expensive diagnostic equipment and the sometimes confusing, if not unreliable diagnoses made by mechanics who are not always as well trained and proficient as they should be.

Provided some basic checks on the general state of the auto electrical system are performed regularly, and all faults are repaired as soon as they happen, (before they cause more serious problems), there should be no reason for anything to fail, blow up, fuse, short circuit, or drop off during an excursion into any part of Southern Africa, or any other part of Africa for that matter.

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