September 2021

SEPTEMBER 2021 AFTERMARKET 45 Below: Cutaway of a NGK spark plug www.aftermarketonline.net Smart charge alternators Meanwhile, on the alternator front, smart charge – or intelligent charge – alternators have been available in the automotive aftermarket for some time, but their design has evolved. Autoelectro UK Sales Manager Nick Hood observed: “Smart charge alternators can usually be identified from their regulator plug type – LIN, BSS or COM, for example. Essentially, a smart charge alternator is controlled externally by the ECU, with information communicated between the two via a cable. The output of these alternators can vary, depending on the information sent to the ECU from the various sensors: the condition of charge of the battery, demands from the vehicle’s electronic parts and accessories, such as heated screens/seats and infotainment systems. “A battery accepts charge more efficiently when it is cold. For this reason, a smart charge alternator will charge at a higher rate to maximise the performance and bring the battery back to optimal operating level. Once this level is achieved, the ECU will reduce the alternator output to supply the vehicle’s demands. It should be noted that the battery charge light affiliated with smart charge alternators is no longer actuated by the alternator itself – but via the ECU. The battery charge limit can illuminate for various reasons, and the vehicle should always be checked for underlying faults before condemning the alternator. “This is common on three-pin regulator Ford type alternators fitted to Fiesta, Focus, Kuga and other similar models (AEK2815). A common fault exists on the vehicle’s wiring loom, which is around 40cm long, in that it has been found that corrosion can occur and can interfere with the connection between the alternator and ECU. “This can lead to the battery charge light illuminating and possibly low or no output from the alternator. Removing the three-pin plug from the back of the alternator will slip the affected part into ‘limp’ mode and should produce between 13.4 and 13.8V, which signifies that the alternator is functioning correctly, and the problem lies elsewhere in the circuit. A vehicle should never be run for a long period of time with the ECU communication cable unplugged.” Different ways Whatever the diagnostic issue at play is, technicians will need to have the right information at their fingertips. “www.hella.com/techworld/uk/ provides technicians with a huge technical resource from which to draw and when it comes to ignition coils,” said HELLA UK’s Senior Head of Marketing and Communications, Helen Goldingay. “If dismantled, there are different ways of checking the ignition coil. When testing the resistance values of the coils using the ohmmeter, depending on the ignition system and ignition coil design, the following reference values apply; Cylinder ignition coil (transistor ignition system) Primary: 0.5 Ω–2.0 Ω/Secondary: 8.0 kΩ–19.0 kΩ Cylinder ignition coil (electronic ignition system with map- controlled ignition) Primary: 0.5 Ω–2.0 Ω/Secondary: 8.0 kΩ–19.0 kΩ Single-spark or dual-spark ignition coil (fully electronic ignition system) Primary: 0.3 Ω–1.0 Ω/Secondary: 8.0 kΩ–15.0 kΩ “If a high-voltage diode is built into an ignition coil to suppress sparks, it is not possible to measure the resistance of the secondary coil. In this case, connect a voltmeter in series between the secondary winding of the ignition coil and a battery. If the battery is connected in the diode's conducting direction, the voltmeter must display a voltage. After reversing the polarity of the connections in the blocking direction of the diode, no voltage must be displayed. If no voltage is indicated in either direction, it can be assumed that there is an interruption in the secondary circuit. If a voltage is indicated in both directions, the high-voltage diode is faulty. “If installed, the following checks can be used. First a visual inspection, checking the ignition coil for mechanical damage, the housing for hairline cracks and sealant leaks and the he electrical wiring and plug connections for damage and oxidation. You can also check the electrics using a multimeter or oscilloscope. Here, you need to check the voltage supply and ignition coil, as well as the triggering signal from the ignition distributor, ignition control unit, or engine control unit. If you are testing with the diagnostic unit, read out the fault memory of the ignition system or engine control, as well as the parameters.” Helen added: “Faults established during tests with the oscilloscope are not necessarily faults caused by the electronic system. They can also be caused by a mechanical problem in the engine. This may be the case, for example, if compression is too low in one cylinder, which means the oscilloscope shows the ignition voltage for this cylinder to be lower than that of the other cylinders.”