If you have noticed that the ABS warning lamp is on, it probably means there is trouble with the system. If a self-diagnosed problem does not cause the ABS light, circumstances may trigger an incorrect code with the component. When this happens, you will still need to figure out the real cause of the ABS warning lamp illumination.
Depending on the application, you might encounter difficulties when you try to pull codes from the ABS. For instance, you will not be able to find the codes on ABS import systems with the early Bosch 2 system. You must perform the special circuits test to isolate the condition that turns the ABS light ON.
If the ABS can provide manual flash codes, the usage of a scan tool is usually not required. But you can still use one to reduce the possibility of reading the wrong code from the system. Systems included in this category include Bosch 2E, 2S, 2U, 3, ITT Teves Mark 2, and Kelsey-Hayes RWAL and 4WAL.
The Bosch 2U ABS is typically used on General Motors vehicles produced from 1990 to 1940. In this application, you can usually manually ground the H terminal on the ALDL connector to acquire the codes. You can then count the flashing light that appears on the ABS lamp. Normally, the flashing codes will appear three times consecutively. The memory will store the codes for up to 50 ignition cycles. A scan tool is required to clear the codes.
GM, Dodge trucks and Ford vehicles produced from 1987 are usually equipped with a system from Kelsey-Hayes RWAL. This application can only store one code at a time. You can still use a scan tool to access the code. General Motors trucks normally have the same manual procedure as other passenger cars. Meanwhile, the pigtail connector on Ford and Dodge trucks will need to be grounded to initiate the flashing light of the ABS.
Some systems, such as the EBC and Kelsey-Hayes 4WAL, can store multiple codes simultaneously. But, this system cannot show manual flash codes for manual inspection. Therefore, a scan tool is always required for inspection.
Manually inspecting the flash codes is also impossible on many newer ABS systems. You will be required to use a scan tool to acquire the codes. The systems included in this category include Bendix 6, 9, 10, ABX-4, Bosch 5 and 5.3, Delco VI, Delco Powermaster III, ITT Teves Mark 4, and Mechatronic.
Some General Motors vehicles are also equipped with special systems, such as Bosch ABS/ASR, used on Cadillac and Corvettes. For the system, using an electronic speedometer can acquire the codes from the system. Pushing the climate control and other buttons can also acquire the driver information center. You must refer to the vehicle’s manual to find the specified sequence of buttons to activate the code-pulling mechanism.
Newer vehicles are usually equipped with newer ABS that can give you more complete diagnostics about the vehicle. The system can usually store data snapshots related to a fault code and its history. They will also be able to receive two-way inputs from a special scan tool. With this, you can check various components of the ABS, including the relays, solenoid valves, pump motor, ABS warning light, ABS circuitry, etc. A more special and sophisticated scan tool is usually required to inspect. Meanwhile, you can also use dedicated ABS testing with a two-way communication capability to connect the scan with the ABS module.
You should also know that the fault codes are usually not the cause of the problem, even though you can pull the codes using a scan tool that can read and clear them. The ABS codes only tell you which component or circuitry you must check. You will not be able to know which components need a replacement. You must refer to the vehicle’s manual for the specified step-by-step diagnostic checks to fix the problem. It would be best if you also eliminated the real cause before repairing. This will save you time and prevent you from fixing the faulty component.
Intermittent problems also tend not to set a fault code. Therefore, you can’t assume every component works properly even though no codes are being shown. Inspecting individual components and overall system operation is necessary to identify issues.
Even without a fault code, you can isolate the problem by pinpointing the voltage and resistance level of the component. But, this process usually requires much time and energy, and the result is inconsistent. It is also impossible to proceed with dynamic tests as this approach will not give you a meaningful result about the ABS valves and solenoids. This is because those components may show the correct reading for assistance and voltage even though the components are damaged. A proper diagnostic will require a specified test for their function. This is also why using a dedicated ABS tester or a scan tool capable of two-way communication can help you immensely.
For instance, the OTC ABS reader can use bi-directional access on the ABS of Powermaster III and Delco VI. Other systems that can be inspected with this scan tool include ITT Teves, Bosch, Kelsey-Hayes, and MECS ABS Systems for Mazda vehicles.
Actron introduced a brand-new ABS BrakeScan tool in 2007. Customers can get an ABS diagnostic tool with affordable pricing for the first time. The scan tool is being sold for under $300 and is a good choice if you want to inspect the ABS. You can use the scan tool for vehicles General Motors, Ford, or Chrysler produced. You can use it by connecting the device to the OBD II connector under the dashboard. The device will be able to read the ABS codes for all related applications and show the definitions of those codes. You can also use an online service to update the tools.
The Fast-Track ABS Troubleshooter from Snap-On can be used to pull the diagnostics of an ABS. This device can display codes and system data, including the lamp and pump motor status, valve positions, wheel speed sensor readings, and more. It can also perform tests to diagnose motor relays, ABS valves, and ABS solenoid valves.