Understanding the ABS sign on your dashboard

Kunle Shonaike

Many motorists are daily inflicted with the psychological pain of seeing the ABS warning light perpetually lit on their vehicles’ dashboards. Albeit, many of them don’t know the meaning of the signage.  A friend told me, “Kunle, I don’t know the meaning but I know any permanent amber or red-coloured light on my dashboard is warning me of a system failure and impending danger that can occur.”

An anti-lock braking system or anti-skid braking system (ABS) is an automobile safety system that allows the wheels on a motor vehicle to maintain tractive or firm contact with the road surface, according to driver’s input while braking, preventing the wheels from locking up (ceasing rotation) and avoiding uncontrolled skidding (especially on, say, a wet road on a rainy day or when a driver has to stop/brake suddenly on a treacherous stretch of track.

It is an automated system that uses the principles of threshold braking and cadence braking which were practised by skilful drivers with previous generation braking systems. It does this at a much faster rate and with better control than many drivers could naturally or instinctively manage.

ABS generally offers improved vehicle control and decreases stopping distances on dry and slippery surfaces. However, on loose gravel or snow-covered surfaces, ABS can significantly increase braking distance, although still improving vehicle steering control.

Since initial widespread use in production of cars, anti-lock braking systems have been improved upon considerably. Recent versions not only prevent wheel-lock under sudden and sharp braking, but also electronically control the front-to-rear brake bias. This function, depending on its specific capabilities and implementation, is known as electronic brake force distribution (EBD), traction control system (TCS), emergency brake assist, or electronic stability control (ESC).

Like my friend, who’s rightly quoted above has stated, the permanently lit ABS sign is a warning sign, which indicates that the safety supplementary system to the conventional braking system of the vehicle is no longer working! Many wonder what the relevance of the vaunted ABS system is if, with its said warning light-supposedly advertising its failure or inactivity-on, “my brakes”, as my friend queried as a follow up to the quote above, “works?”

The lit warning ABS sign does not mean that the vehicle’s conventional brake will not hold. But if the brake in such a vehicle were to be suddenly applied in an emergency situation, or on a dodgy track, then the importance of the ABS, which stabilises the vehicle and prevents it from skidding or flipping off the road, can be felt.

“What then should I do when I see the sign on my vehicle’s dashboard?” my lawyer friend further asked. Like all warning lights, any lit sign is primarily telling you to take the vehicle for diagnosis to specifically laser in on, in this particular instance, what’s wrong with the ABS system. Once the particular problem has been identified, then the auto technician working on it (using the vehicle’s manufacturer’s workshop manual’s protocol or recommended repair procedure for the scan code/s pulled during the diagnosis) can solve the problem.

NB: Some parts of this piece were culled from the Internet.

Feedback

Thanks for all the information in AUTOPUNCH. Please can the airbags in a vehicle expire and burst in motion without an impact? Thanks for your prompt response.

No, airbags do not have an expiry date. But it can sometimes deploy without having an accident. Running into a bump or pothole with an equivalent force of an accident will simulate, indeed stimulate, an impact which can deploy any of SRS systems.

Thank you for the great automobile insight that you give in SUNDAY PUNCH. My 2013 Hyundai Sante-Fe has the following problems: (1) Does not fire at all, (2) Does not change gear easily. Kindly advise me on what could be fundamentally wrong with vehicle. —Ayuba Steve

Please, run a diagnostic scan on the powertrain system. The results will guide you or your technician on what to do.

Diagnostic codes

P0361 – Ignition Coil 11 Primary/Secondary Circuit Malfunction:

The ignition system on the vehicle uses individual ignition coils for each cylinder. The Engine Control Module (ECM) controls each ignition coil operation. The ECM sends an on/off signal to energise the ignition coil to create a spark at the spark plug when a spark is required at the cylinder.

The code is detected when each ignition circuit is continuously monitored by the ECM. The test fails when the ECM does not receive a valid pulse signal from the ignition coil.

Possible symptoms: Engine Light on (or Service Engine Soon Warning Light), lack/loss of power, engine may be harder to start, engine hesitation, rough engine idle.

Possible causes: Faulty Ignition Coil 11, Ignition Coil 11 harness is open or shorted, Ignition Coil 11 circuit poor electrical connection, faulty ECM.

P0362 – Ignition Coil 12 Primary/Secondary Circuit Malfunction:

The ignition system on the vehicle uses individual ignition coils for each cylinder. The ECM controls each ignition coil operation. The ECM sends an on/off signal to energise the ignition coil to create a spark at the spark plug when a spark is required at the cylinder.

The code is detected when each ignition circuit is continuously monitored by the ECM. The test fails when the ECM does not receive a valid pulse signal from the ignition coil.

Possible symptoms: Engine Light on (or Service Engine Soon Warning Light), lack/loss of power, engine may be harder to start, engine hesitation, rough engine idle.

Possible causes: Faulty Ignition Coil 12, Ignition Coil 12 harness is open or shorted, Ignition Coil 12 circuit poor electrical connection, faulty ECM.

P0363 – Misfire Detected Fuelling Disabled

P0400 – Exhaust Gas Recirculation Flow Malfunction:

Early Exhaust Gas Recirculation (EGR) systems components include EGR Valve, and ECΜ Controlled Vacuum Switch Valve or EGR Solenoid and an EGR Vacuum Modulator. Depending on the engine and driving conditions, the ECΜ will control the EGR Solenoid, which will operate the EGR Vacuum Μodulator to regulate the opening and closing of the EGR Valve.

The EGR system on recently built vehicles uses a step motor to control the flow rate of EGR from exhaust manifold. This motor has four winding phases. It operates according to the output pulse signal of the ECΜ. Two windings are turned on and off in sequence. Each time an ON pulse is issued, the valve opens or closes, changing the flow rate. When no change in the flow rate is needed, the ECΜ does not issue the pulse signal. Α certain voltage signal is issued so that the valve remains at that particular opening.

EGR flow malfunction could be caused by a clogged EGR valve or EGR tube. Before replacing any parts, try cleaning the EGR valve, tube and passages.

The code is detected when the Exhaust Gas Recirculation (EGR) flow control is not responding.

Possible symptoms: Engine Light on (or Service Engine Soon Warning Light), possible engine hesitation.

Possible causes: EGR volume control valve stuck closed, faulty EGR volume control solenoid valve, faulty EGR valve, faulty EGR temperature sensor and circuit, EGR solenoid valve harness is open or shorted, EGR solenoid valve circuit poor electrical connection, dead (weak) battery.

P0401 – Exhaust Gas Recirculation Flow Insufficient Detected Repair Importance Level: 2/3:

Early EGR systems components include EGR Valve and ECΜ Controlled Vacuum Switch Valve or EGR Solenoid and an EGR Vacuum Modulator. Depending on the engine and driving conditions, the ECΜ will control the EGR Solenoid which will operate the EGR Vacuum Μodulator to regulate the opening and closing of the EGR Valve.

The EGR system on recently built vehicles uses a step motor to control the flow rate of EGR from exhaust manifold. This motor has four winding phases. It operates according to the output pulse signal of the ECΜ. Two windings are turned on and off in sequence. Each time an ON pulse is issued, the valve opens or closes, changing the flow rate. When no change in the flow rate is needed, the ECΜ does not issue the pulse signal. Α certain voltage signal is issued so that the valve remains at that particular opening.

EGR flow malfunction could be caused by a clogged EGR valve or EGR tube. Before replacing any parts, try cleaning the EGR valve, tube and passages.

The code is detected when low EGR flow control is detected.

Possible symptoms: Engine Light on (or Service Engine Soon Warning Light), possible engine hesitation.

Possible causes: EGR passage clogged, faulty EGR Vacuum Modulator Valve, faulty EGR Valve, faulty EGR solenoid valve, EGR solenoid valve harness is open or shorted, EGR solenoid valve circuit poor electrical connection, dead (weak) battery, faulty EGR temperature sensor and circuit, exhaust gas leaks.

P0402 – Exhaust Gas Recirculation Flow Excessive Detected:

Early EGR systems components include EGR Valve and ECΜ Controlled Vacuum Switch Valve or EGR Solenoid and an EGR Vacuum Μodulator. Depending on the engine and driving conditions, the ECΜ will control the EGR Solenoid which will operate the EGR Vacuum Μodulator to regulate the opening and closing of the EGR Valve.

The EGR system on recently built vehicles uses a step motor to control the flow rate of EGR from exhaust manifold. This motor has four winding phases. It operates according to the output pulse signal of the ECΜ. Two windings are turned on and off in sequence. Each time an on pulse is issued, the valve opens or closes, changing the flow rate. When no change in the flow rate is needed, the ECΜ does not issue the pulse signal. Α certain voltage signal is issued so that the valve remains at that particular opening.

The code is detected when high EGR flow control is detected.

Possible symptoms: Engine Light on (or Service Engine Soon Warning Light), possible engine hesitation.

Possible causes: EGR volume control valve stuck open, faulty EGR volume control valve, EGR solenoid valve harness is open or shorted, EGR solenoid valve circuit poor electrical connection, faulty EGR temperature sensor and circuit.

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