2: When Ignition "on" (Engine Stopped the ABS Light Stays Off
INSPECTION PROCEDURE 2: When the Ignition Key is Turned to "ON" (Engine Stopped), the ABS Warning Light does not Illuminate.
Part 1 of 2
Part 2 of 2
CIRCUIT OPERATION
- The ABS warning light power is supplied from the ignition switch. The ABS-ECU grounds the circuit to illuminate the light.
- The ABS-ECU illuminates the ABS warning light for 3 seconds while running self-check. This light can be illuminated for 3 seconds upon start-up or when the ignition switch is turned to the "ON" position with engine stopped.
- When the ABS-ECU connector is disconnected, the circuit is grounded to illuminate the light by the ABS warning light relay ON operation.
- The ABS-ECU controls the continuity to the ABS warning light by turning the power transistor in the unit "OFF" and "ON" to turn the ABS warning light relay "ON" and "OFF", respectively.
TECHNICAL DESCRIPTION (COMMENT)
The cause may be: an open circuit in the ABS warning light power supply circuit, a blown ABS warning light bulb, or a short circuit to ground between the ABS warning light and the ABS-ECU.
TROUBLESHOOTING HINTS (The most likely causes for this case:)
- Blown fuse
- Damaged wiring harness or connector
- Burnt out ABS warning light bulb
- Malfunction of the ABS warning light relay
- Malfunction of the hydraulic unit (integrated with ABS-ECU)
DIAGNOSIS
Required Special Tool:
- MB991223: Harness Set
STEP 1. Check the ABS warning light relay circuit at ABS-ECU connector B-118.
1) Disconnect ABS-ECU connector B-118.
2) Turn the ignition switch to the "ON" position.
Q: Does the ABS warning light illuminate?
YES: Replace the hydraulic unit (integrated with ABS-ECU) and then go to Step 10.
NO: Go to Step 2.
STEP 2. Check the ABS warning light relay.
1) Remove the ABS warning light relay.
2) Check the continuity between terminals 2 - 5 when battery voltage is applied between terminals 1 - 3.
Q: Is the ABS warning light relay normal?
YES: Go to Step 3.
NO: Replace it and then go to Step 10.
STEP 3. Check the ABS warning light circuit at ABS warning light relay connector C-213.
1) Disconnect ABS warning light relay connector C-213 and measure at the harness side.
2) Ground terminal 5.
3) Turn the ignition switch to the "ON" position, and then ABS warning light should turn on.
Q: Does the warning light turn on?
YES: Go to Step 9.
NO: Go to Step 4.
STEP 4: Check the ABS warning light bulb.
1) Remove the combination meter
2) Check the ABS warning light bulb.
Q: Is the bulb burned out?
YES: Replace the bulb and then go to Step 10.
NO: Go to Step 5.
STEP 5. Check the combination meter for continuity.
1) Remove the combination meter.
2) Remove the ABS warning light bulb. Then measure the resistance between the bulb terminals.
3) Install the ABS warning light bulb to the combination meter, and then measure the resistance between connector C-01 terminal 9 and terminal 13. The resistance reading at this time should be much the same as the resistance measured at step (2).
Q: Are the two resistance values extremely different each other?
YES: Replace the combination meter (printed circuit board) and then go to Step 10.
NO: Go to Step 6.
STEP 6. Check the combination meter power supply circuit.
1) Disconnect connector C-01, and check at the harness side.
2) Turn the ignition switch to the "ON" position.
3) Measure the voltage between terminal 9 and ground. It should be approximately 12 volts (battery positive voltage),
Q: Is the voltage approximately 12 volts (battery positive voltage)?
YES: Go to Step 7.
NO: Go to Step 8.
STEP 7. Check the continuity between the combination meter and the ABS warning light relay.
NOTE: After inspecting combination meter connector C-01 and ABS warning light relay connector C-213, inspect the wire. If the combination meter connector C-01 and ABS warning light relay connector C-213 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 10.
Q: Is the harness wire between combination meter connector C-01 and ABS warning light relay connector C-213?
YES: Go to Step 10.
NO: Repair the harness wire and then go to Step 10.
STEP 8. Check the continuity between the ignition switch (IG1) and the combination meter.
NOTE: After inspecting intermediate connectors C-01, C-21, C-211 and C-214, inspect the wire. If the intermediate connector C-01, C-21, C-211 or C-214 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 10.
Q: Is there any continuity (less than 2 ohm) between the ignition switch (IG1) and combination meter connector C-01 (terminal 9)?
YES: Go to Step 10.
NO: Repair the harness wire and then go to Step 10.
STEP 9. Check the continuity between the ABS warning light relay and ground.
NOTE: After inspecting intermediate connector C-06, inspect the wire. if intermediate connector C-06 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 9.
Q: Is there any continuity between the ABS warning light relay and ground?
YES: Go to Step 10.
NO: Repair the harness wire and then go to Step 10.
STEP 10. Check symptoms.
Q: Does the ABS warning light illuminate for 3 seconds when the ignition switch is turned to the "ON" position with engine stopped or upon start-up?
YES: This diagnosis is complete.
NO: Return to Step 1.