Due to the critical nature of the first generation electro-hydraulic ABS brake system found on the Lincoln Mark VII's and other makes, and also due to their complexity and relatively high cost, I figured I'd make a quick video going over some of the more common issues with these units and their solutions. These are high quality units made by ATE in Germany, but nothing lasts forever and they will eventually develop problems.

There are about three problems that can develop with these units:

- Diaphragm accumulator failure
- Pressure cut-off switch failure
- ABS pump relay failure

The most common problem with these units is that the nitrogen filled diaphragm accumulator leaks to the point where it will no longer hold pressure. Symptoms of this condition are a brake light that illuminates every time the brake pedal is depressed. These accumulators can be sourced through Prior Remanufacturing out in TX and are made by Hydac.

The second problem than can crop up is a failed pressure switch. When failed closed, the ABS pump motor will run constantly. When failed open, the pump motor will never operate and the brake light will be on, along with a hard pedal. I'm not sure of the availability of the pressure switch since I've never had one fail.

Finally, the ABS pump relay's contacts can become burned causing the pump motor to not operate. The relay is easy to replace and is available in most auto parts stores. This was only a brief, spur of the moment video to introduce viewers to this technology and how to maintain it. Bleeding the brake system is the best way to ensure against system failures.

If you need to replace the accumulator, make 100% sure that the system pressure is properly bled off by pumping the brake pedal at least 20 times without the ignition switch on. A fully pressurized system can generate 3,000 PSI which can cause quite a bit of damage if not handled properly.(4/29/2013)

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