Isolation Test with Remy

One of the biggest challenges in the industry is diagnosing a low/spongy brake pedal. In today's video, we will walk you through the process of performing an isolation test. This will help you quickly and accurately determine the cause of a low/spongy brake pedal.

Isolation Test Steps

1.) Make sure you are using the right tool. Use a tool that will not flatten out the brake hose. Do not use a pair of vice grips.

2.) Clamp off the brake hose behind the wheel hub assembly on all four wheels.

3.) Start the vehicle to evaluate the pedal height. If the pedal is hard, that means the problem lies below the clamps (skip to step 6). If the pedal is soft, that means the problem is above the clamps.

4.) Remove the brake lines from the master cylinder and plug the ports. If you still have a spongy pedal, the master cylinder must be replaced. If the pedal is hard, this means that the problem lies between the master cylinder and the clamped off hose.

5.) Inspect the brake lines and hoses between the master cylinder and where the hose is clamped off. If there are no leaks, the problem is probably air trapped in the ABS module. You may need to use a scan tool to cycle the ABS unit to remove the trapped air.

6.) Remove one of the clamps. If the pedal is soft, that means there is a problem at that wheel. If the pedal is hard, reattach the clamp and repeat the process at each wheel until a soft pedal is identified.

7.) A problem below the clamps could be any number of problems, including air trapped in the hose, a leak, excessive movement of the caliper pistons or wheel cylinders, etc. Do a proper brake inspection to determine the problem.

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