Clearing Diagnostic Trouble Codes

Fault codes stored in the EBCM's memory can be erased in one of the three following ways:
1. Diagnostic Enable Line Procedure.
2. Tech 1 ``Clear Codes'' Procedure.
3. Ignition Cycle Default.

Whichever method is used, ensure to verify proper system operation and absence of fault codes when clearing procedure is completed.
The EBCM will not allow codes to be cleared until all codes have been displayed. Codes cannot be cleared by disconnecting the EBCM, disconnecting battery cables or turning the ignition Off.

Diagnostic Enable Line Procedure
Clear codes using ALDL enable line (pin H) as follows:
1. Turn ignition Off.
2. Ground ALDL pin H.
3. Turn ignition On.
4. Wait for codes to begin flashing.
5. Unground pin H for at least one second, then ground pin H. This must be done three times within ten seconds.
6. Wait at least 15 seconds. Before turning ignition Off, verify that Code 12 is the only code being flashed. If not, codes have not been properly cleared. Repeat above procedure.

Tech 1 ``Clear Codes'' Procedure
Following tool manufacturer's instructions, select the appropriate menu, then select the ``Clear Codes'' function. Verify that codes are cleared by using Tech 1 to read codes. Refer to ``Tech 1 Diagnostics'' for procedure. If any codes other than Code 12 are present, codes were not cleared or a fault is still present.

Ignition Cycle Default
If the ignition is cycled 100 times without a particular fault reappearing, that particular fault code will be erased and the ignition cycle counter will be reset to zero.