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DTC 42 POWER SUPPLY VOLTAGE TOO LOW

DTC 42 POWER SUPPLY VOLTAGE TOO LOW

DIAGNOSIS:

Power source voltage of the ABSCM&H/U is low.

TROUBLE SYMPTOM:


• ABS does not operate.

• EBD does not operate.

Note

In addition to the ABS warning light, brake warning light illuminates temporarily. Both warning lights go off on the recovery of voltage.



WIRING DIAGRAM:


CHECK GENERATOR.

Start the engine.

Idle after warm-up.

Measure the voltage between generator B terminal and chassis ground.

Terminals

Generator B terminal (+) — Chassis ground (−):

Is the voltage 10 — 17 V?

Yes


No

Repair the generator.


CHECK BATTERY TERMINAL.

Turn the ignition switch to OFF.

Are the positive and negative battery terminals tightly clamped?

Yes


No

Tighten the clamp of terminal.


CHECK INPUT VOLTAGE OF ABSCM&H/U.

Disconnect the connector from ABSCM& H/U.

Run the engine at idle.

Operate the electric load applying devices, such as the headlight, A/C, and defogger.

Measure the voltage between ABSCM&H/U connector and chassis ground.

Connector & terminal

(B301) No. 18 (+) — Chassis ground (−):

Is the voltage 10 — 17 V?

Yes


No

Repair the harness connector between battery, ignition switch and ABSCM&H/U.


CHECK GROUND CIRCUIT OF ABSCM&H/U.

Turn the ignition switch to OFF.

Measure the resistance between ABSCM&H/U connector and chassis ground.

Connector & terminal

(B301) No. 15 — Chassis ground:

Is the resistance less than 0.5 Ω?

Yes


No

Repair the ABSCM&H/U ground harness.


CHECK POOR CONTACT IN CONNECTORS.

Is there poor contact in connectors between generator, battery and ABSCM&H/U?

Yes

Repair the connector.


No


CHECK ABSCM&H/U.

Connect all connectors.

Erase the memory.

Perform the inspection mode.

Read out the DTC.

Is the same DTC as in the current diagnosis still being output?

Yes

Replace the ABSCM&H/U.


No


CHECK ANY OTHER DTC APPEARANCE.

Are other DTCs being output?

Yes

Proceed with the diagnosis corresponding to DTC.


No

A temporary poor contact.