This Procedure is only for the Discovery Series I vehicles!
This will not work on the Series II Discovery! So Do Not try it and come complaining to me.
If an external diagnostic tool is not available, the following procedures can be carried out to determine the cause of an ABS fault message. The faults can be retrieved by jumping a series of pins and reading the series of blink codes through the ABS warning lamp.
First, you will need to create a jumper wire out of something close to 16 gauge wire. Locate the Testbook diagnostic connector located under the dash panel. Connect the Jumper wire to pins 5 and pins 15. Turn the key to the second position. 5 seconds after the ignition is turned to the second position, the Anti-Lock warning light will extinguish. When the light extinguishes, this signals the start of the blink code cycle. The code below indicates the beginning of the fault retrieval blink sequence.
The second series of blink codes, will describe the actual fault code number. The first part of the code is signaled by a pause of 2.5 seconds. Immediately following is a series of short flashes then a long pause. The number of short flashes will equal the first digit in the stored fault code.
The second digit in the fault code is determined after a 2.5 second pause. This pause occurs between the first and second digit blink signals. After the 2.5 second pause, there will be another series of short flashes. The number of flashes corresponds to the second digit in the stored ABS fault code. After the second digit is signaled, there will be a pause of 2.5 seconds before the system repeats the stored fault code. This allows for you to see the code again if it was missed the first time. I would also suggest watching the sequence again just to make sure that you got it right the first time through. The diagram below indicates a stored fault code of 2-2.
The above sequence will continue until the jumper wire is removed. Once the jumper wire is removed, that single fault code will be cleared. Do not remove the jumper until the fault code has been recorded. Otherwise is cleared and gone when the jumper is removed.
To view all the faults stored in the ABS computer, repeat the above procedure starting with inserting the jumper wire. If there are no remaining faults, there will be a long 7.5 second pause after the start phase.