ISB/ISBe Series Engines - 019-325 Tachograph Circuit

General Information
Resistance Check
Check for Short Circuit to Ground
Check for Short Circuit from Pin to Pin

General Information

TOC

The ECM can supply an output signal to operate the vehicle tachograph. The circuit consists of wire number 57, the input signal, and wire number 54, the return wire.

Refer to the OEM troubleshooting and repair manual for troubleshooting instructions.

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Resistance Check

TOC

CAUTION

To reduce the possibility of damage to the connector pins, do not use probes or leads other than Part Numbers 3164110 and 3164112. The leads must fit tightly in the connector without expanding pins of the connector.

Remove the 89-pin OEM harness connector from the ECM. Disconnect the tachograph from the OEM harness.

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Locate the tachograph connector of the OEM harness.

Connect the other lead of a multimeter to the connector terminal at the tachograph that is coming from the engine ECM. Consult the equipment manufacturer’s repair manual for wiring schematics.

Set the multimeter to measure resistance, and measure the resistance.

The multimeter must show a closed circuit (10 ohms or less). If the circuit is not closed, there is an open circuit or the wires in the tachograph connector are reversed. Repair or replace the wire connected to pin 57 in the 89-pin OEM harness connector. Refer to Procedure 019-071.

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Check for Short Circuit to Ground

TOC

Disconnect the tachograph from the OEM harness.

Connect the multimeter lead to pin 57. Touch the other multimeter lead to the engine block. Measure the resistance.

The multimeter must show an open circuit (100k ohms or more).

If the circuit is not open, repair or replace the OEM harness. Refer to Procedure 019-071.

SMALL | MEDIUM | LARGE

Check for Short Circuit from Pin to Pin

TOC

Place the multimeter lead into pin 57 of the OEM harness connector. Connect the other lead to pin 1 of the OEM harness connector, and measure the resistance.

The multimeter must show an open circuit (100k ohms or more).

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Remove the lead from pin 1 and check all other pins. Measure the resistance. The multimeter must show an open circuit (100k ohms or more)
at all pins. If the multimeter does not show an open circuit at any pin, a short circuit exists between pin 57 and any pin that reads less than 100k ohms. Repair or replace the OEM harness. Refer to Procedure 019-071.