Faulty sensor may be culprit

Q1:  The anti-skid and brake indicators in my car would come on when the car is used after it is up to normal operating temperature. They do not light up during cold-starting.

What could be wrong?

Lam
Sentul, Kuala Lumpur

The anti-skid system comprises sensors, actuators, ABS ECU (electronic control unit), HCU (hydraulic control unit) and other switches or connectors. If any of them is defective, the ABS ECU will store the fault code. The best troubleshooting method is to use diagnostic tools to pinpoint the actual source of the problem.

A defective sensor might be the cause. Test the sensors that relay signals to the anti-skid and brake system and if there’s a problem, service the defective sensor.

Some models need only a re-set and the problem will be solved. Go to your service centre to have your car checked properly.


Q2: I recently bought a second-hand Toyota Altis and the light on the 'A/C' button blinks occasionally. When it's blinking, the air-cond outlet will still blow air, but it's not cold. It will blow cold air again if I restart the air-cond by pressing the button off and on. However, this method is only effective once in a while.

I went to few mechanics but each gave me a different answer on the 2001 car. Some told me it's because of a blocked filter valve or a faulty compressor.

Is the compressor at fault even though it's still blowing air out?

Simon
Puchong

The flowing air comes from your fan blower, not your air-cond. There are many possible reasons why your air-cond is not working properly.

After a thorough testing and diagnosis, your mechanic should find a component that is not working according to the specification. Re-set or adjust where such option is available. If there's no such avenue, the only recourse is to replace the damage component(s).


Q3: I am driving a 2006 Toyota Vios and it has clocked 70,000km now.

The car's engine tends to vibrate intermittently at idle especially when I feel the compressor kicking in and the engine speed dropping then recovering after a while. The vibration is worst at night when all lights are on.

How do I correct the situation?

Louis
Klang

The vibration could be the result of engine speed dropping leading to a power loss at idle.

Tune the engine using a diagnostic tool to restore normal functions.

Check the idle speed mechanism to see if it is working properly.

Make sure your car goes for its scheduled service maintenance.