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Greg, Technician
Category: Car
Satisfied Customers: 7284
Experience:  Automotive diagnostic tech
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abs and brake warning light comes on when first start up but

Customer Question

abs and brake warning light comes on when first start up but goes out after running 10 minutes
Submitted: 3 years ago.
Category: Car
Expert:  Shantal-Mod replied 3 years ago.

I'm Shantal and I'm a moderator for this topic.

We have been working with the Experts to try to help you with your question. Sometimes it may take a bit of time to find the right fit.

I was checking to see if you had already found your answer or if you still need assistance from one of the Experts.

Please let me know if you wish to continue waiting or if you would like for us to close your question?

Thank you,

Expert:  Greg replied 3 years ago.
Name is Greg, My goal is to provide you with excellent service – if you feel you have gotten anything less, please reply back,

Hi .

You have a possible ABS sensor malfunction or your brake fluid is too low just at the point when the brake fluid get hot it slightly expands
and cut off the low fluid warning light which in turn will switch off the ABS light so first check the brake fluid level.

If good then you will need a good ABS diagnostic scan tool to check for ABS malfunction codes .

When you have the codes then you will know what you are up against .

The most common issue is likely to be one of the wheel speed sensors .

The scan tool is needed to make sure you know which sensor you have to change.

If you can get the codes and need my assistance then please get back to me with the code .

If you still need further assistance then please don't rate, just get back to me with the reply button, and I will get back to you or inform another expert to assist.
Also there is no extra charge after accepting .

Kindest regards Greg
Customer: replied 3 years ago.

Thank you for your time. The abs and brake warning come on even when the ignition is switched on without starting the engine and remain on when the engine is started. Brake fluid level is alright. These warning lights go out sooner the warmer the weather and sometimes the system is perfect with no warning lights in hot weather. I do not have a fault code machine. What is actually being checked which decides is everything is okay?

Expert:  Greg replied 3 years ago.
Hi .

I have just been though some V70 ABS system malfunctions and i have found that you may have a Controller failure, this is why you will need a ABS scan tool to check this issue .

The ABS System.

The ABS consists of certain interlinked components that help it achieve its intended purpose.

They are as follows:

Speed sensors.

The Controller.

The controller is the central unit which receives signals from the wheel sensors and accordingly transmits the signals to activate the ABS modulator (valves and pump).
This is the intelligent part of the system and parameters such as wheel lock up speed, pressure variation i.e. minimum and maximum pressure values at the brake pads, acceleration and deceleration values are continuously monitored by it.

Any of the system fails and the controller will see this and trip the warning light ON to let you know there is a problem .

Now your brake system will not be affected will work only the ABS system will be deactivated .

Rgds Greg