Vespa GTS Super 300 ie - Service manual > Diagnostic instrument

STARTER COMMAND

Function

Commands engine starting through the injection control unit.

Operation / Operating principle

The starter button, the brake switches, the starter relay and the injection control unit through PIN 10 are involved.

ELECTRICAL ERRORS

Starter command P0170 - shorted to positive

Error cause

Shorted to positive: excessive voltage at PIN 10 of the control unit connector.

Troubleshooting

Short circuit to positive:

• This malfunction is detected with a brake activated and the starter button pressed.
• If the battery voltage does not drop (thanks to the absorption of the starter command relay excitation coil) the control unit understands that PIN 10 is shorted to battery.
• Restore the cabling (if the short is in the cabling) or the relay (if the short is in the relay).

COIL

Function

Allows generation of the electrical discharge on the spark plug, with an increase of voltage.

Pinout:

1. Power from relay
2. Activation by control unit (control unit side PIN 1)

ELECTRICAL ERRORS

H.V. Coil P0351 - shorted to positive / open circuit or shorted to negative.

Error cause

Shorted to positive: excessive voltage at PIN 1 of the control unit connector.

Circuit open or short circuit to negative:interruption of the circuit or null voltage at PIN 1 of the control unit connector.

Troubleshooting

Short circuit to positive:

• Disconnect the coil connector, turn the key to ON and activate the component through the diagnostics instrument.
• Verify the presence of voltage on the coil connector PIN 2: if present, restore the cabling, otherwise replace the coil.

Open circuit:

• Carry out the check procedure of the coil and control unit connectors.
• Verify continuity of the cabling between the coil and control unit: Coil PIN 2 - control unit PIN 1. If there is no continuity, restore the cable harness.
• Verify, with the key turned ON, the presence of voltage on the coil connector PIN 1. If no voltage is detected, check that the cable harness between the coil and injection relay is not interrupted: PIN 1 coil - relay.
• If the above tests provided a positive result, the coil should be replaced.

Short circuit to negative:

• Disconnect the control unit connector and the coil connector.
• Verify the coil connector PIN 2 ground insulation (or control unit connector PIN 1). If necessary, restore the cable harness.

INJECTOR

Function

Provide the correct amount of fuel at the correct time.

Operation / Operating principle

Injector coil is excited for the petrol passage to open.

Pinout:

1. Power from relay
2. Ground from control unit

ELECTRICAL ERRORS

Injector P0201 - shorted to positive / shorted to negative / open circuit.

Error cause

Shorted to positive: excessive voltage to PIN 34 of the control unit connector.

Shorted to negative: zero voltage to the PIN 1 of the injector connector.

Open circuit: circuit interruption.

Troubleshooting

Shorted to positive:

• Disconnect the injector connector, turn ignition switch to ON and activate the component using the diagnostic tool.
• Verify the absence of voltage at the injector connector PIN 2; if present restore the cable harness, otherwise proceed with the following checks.

Shorted to negative:

• Disconnect the injector connector, turn ignition switch to ON and activate the component using the diagnostic tool.
• Verify the presence of voltage at the ends of the injector connector; if there is no voltage, restore the cable harness, otherwise proceed with the following checks.

Open circuit:

• Perform the check of the injector and control unit connectors.
• Verify continuity of the cable harness between the control unit connector and the injector connector (control unit PIN 34 - injector PIN 2). If there is no continuity, restore the cable harness.

FUEL PUMP

ELECTRICAL ERRORS

Fuel pump relay P0230 - shorted to positive / shorted to negative / open circuit.

Error cause

Shorted to positive: excessive voltage at PIN 22 of the control unit connector.

Short circuit to negative: null voltage at PIN 86 of the injection relay.

Open circuit: circuit interruption.

Troubleshooting

Short circuit to positive:

• Disconnect the injection relay, turn the key to ON and activate the relay through the diagnostics instrument.
• Verify the presence of voltage between relay connector PIN 86 and 85 toward the cabling.
• If no voltage is read, disconnect the control unit and verify insulation from battery positive of the relay PIN 85 (or control unit PIN 22). If necessary, restore the cable harness.

Short circuit to negative:

• Disconnect the injection relay and the control unit.
• Verify ground insulation of the relay connector PIN 86 and 85 toward the cabling: if there is no insulation, restore the cabling.

Open circuit:

• Disconnect the injection relay and the control unit.
• Verify continuity of the cabling between the relay and control unit: Relay PIN 85 - control unit PIN 22.

If necessary, restore the cable harness.

ELECTRIC FAN CIRCUIT

Function

Radiator fan and coolant - Operation.

Operation / Operating principle

The control unit closes the fan control relay excitation circuit to ground until the temperature drops.

ELECTRICAL ERRORS

Fan relay P0480 - shorted to positive / shorted to negative / open circuit.

Error cause

Shorted to positive: excessive voltage at PIN 24 of the control unit connector.

Shorted to negative: null voltage at PIN 24 of the control unit connector.

Open circuit: circuit interruption.

Troubleshooting

Short circuit to positive:

• Disconnect the fan control relay and, turning the key to ON position, measure the voltage read at PIN 85 of the relay connector to the cable harness: if the voltage is 12V restore the cabling. If the voltage is zero replace the relay.

Short circuit to negative:

• Disconnect the fan control relay and the control unit.
• Verify ground insulation of the cable between the fan control relay (PIN 85) and the control unit (PIN 24). Restore the cabling if necessary.

Open circuit:

• Carry out the check procedure of the control unit and relay connectors.
• Verify electrical continuity of the cable between the relay connector (PIN 85) and the control unit connector (PIN 24).
• Verify electrical continuity of the cable between the relay connector (PIN 30) and the secondary fuse holders.
• Verify continuity between relay PIN 85 and PIN 86. If there is no continuity replace the relay.

ENGINE TEMPERATURE SENSOR

Function

Serves the purpose of communicating the engine temperature to the control unit in order to optimise performance.

Operation / Operating principle

NTC type sensor (resistance sensor, inversely variable with temperature).

Pinout:

1. Ground from control unit
2. Instrument panel
3. Injection ECU
4. Ground lead

Engine temperature sensor P0115 - open circuit or shorted to positive / shorted to negative.

Error cause

Open circuit or short circuit to positive:interruption of the circuit or excessive voltage at PIN 13 of the control unit connector. Short circuit to negative: null voltage between PIN 13 and 7 of the control unit connector.

Troubleshooting

Open circuit:

• Disconnect the connector of the control unit.
• Measure the resistance value of the sensor at different temperatures between PIN 13 and 7.
• Disconnect the sensor connector.
• Check the continuity of the cable harness between the sensor connector and control unit connector:
  Control unit PIN 13 - sensor PIN 3 and control unit PIN 7 - sensor PIN 1. If necessary, restore the cable harness.
• If the cabling is intact but the sensor resistance value is incorrect, this means that the sensor is faulty and must be replaced, otherwise proceed with the checks.

Short circuit to positive:

• With the sensor connector and the control unit disconnected, verify that the fault is shorted with the battery positive of sensor connector PIN 3 (or control unit PIN 13) and restore the cabling.

Short circuit to negative:

• Disconnect the sensor connector.
• Check the sensor connector PIN 3 from ground insulation.
• If there is no ground insulation restore the cabling.
• If PIN 3 is insulated from the ground and the error persists, this means that there is a probable fault in the control unit.

LAMBDA PROBE

Function

In charge of telling the control unit whether the mixture is lean or rich.

Operation / Operating principle

Based on the difference of oxygen in the exhaust fumes and the environment, this generates voltage which is read and interpreted by the injection control unit.

Pinout:

1. Signal to the control unit (+)
2. Signal to the control unit (-)

ELECTRICAL ERRORS

Check the air-fuel ratio / Lambda probe P0130 - short circuit to positive / open circuit, short circuit to negative or carburetion excessively lean / signal not plausible for abnormal title correction or probe signal fault.

Error cause

Short circuit to positive: excessive voltage to PIN 11 or PIN 12 of the control unit connector. Open circuit or short circuit to negative: interruption of the circuit or zero voltage between the pins 11 and 12 of the control unit connector.

Troubleshooting

Short circuit to positive:

• Disconnect the control unit connector and the sensor connector.
• Verify that there is no short circuit with the battery positive on the PIN 1 of the sensor connector (corresponding to the PIN 11 of the control unit connector); in the presence of short circuit, restore the cable harness.
• Verify that there is no short circuit with the battery positive on the PIN 2 of the sensor connector (corresponding to the PIN 12 of the control unit connector); in the presence of short circuit, restore the cable harness.

Open circuit:

• Disconnect the control unit connector and the sensor connector.
• Check the continuity of the cable harness between the sensor connector and control unit connector: PIN 11 of the control unit - PIN 1 of the sensor and PIN 12 of the control unit - PIN 2 of the sensor. If necessary, restore the cable harness.
• If the cable harness is intact and the error persists, proceed with the following checks.

Short circuit to negative:

• Disconnect the sensor connector and the control unit connector.
• Check the insulation from the ground of PIN 1 of the sensor connector. If there is no insulation, restore the cable harness.
• Check the insulation from the ground of PIN 2 of the sensor connector. If there is no insulation, restore the cable harness.
• If PIN 1 and 2 are insulated from ground and the error persists, it means that there is a probable defect in the control unit.

See also: