Chart B Flash Code Diagnosis

CIRCUIT DESCRIPTION
When the ignition switch is first turned to "ON," system voltage is applied from Fuse C-22 to the DERM at the "SIR Indicator High" input, terminal "B9," and to the "INFL REST" indicator (located in the instrument cluster) which is connected to the "SIR Indicator Low," terminal "A1." Fuse C-23 applies system voltage to the "Ignition 1" input, terminals "A3" and "B3." The DERM responds by flashing the "INFL REST" indicator 7 to 9 times.

When the engine is being cranked, system voltage is applied from Fuse C-21 to the DERM and the "Crank" input, terminal "B10." The DERM responds by grounding the "SIR Indicator Low" output until system voltage is removed from the "Crank" input. This results in the "INFL REST" indicator being illuminated steady during cranking.

After cranking, the DERM will again flash the "INFL REST" indicator 7 to 9 times.

TEST DESCRIPTION:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test determines whether "Flash Code" diagnostics can be
enabled.
2. This test checks for a good ground at the DERM DLC (CKT 450).
3. This test checks for an open in the "Diagnostic Request Input" CKT 326.
4. This test checks for a short to B+ in the "Diagnostic Request Input" CKT 326.
5. This test determines whether further diagnosis is required.
6. This test determines whether only history or both current and history DTCs exist.