The on-board diagnostics system signals the presence of a malfunction by turning on the indicator
Then the on-board diagnostics system must ensure, using special equipment, the receipt of diagnostic information stored in the controller's memory.
For this purpose, a serial information transmission channel is organized in the engine management system, which includes the ECM controller, a standardized connector for connecting the diagnostic device (Fig. 1) and a wire connecting them (K-line).
In addition to the connector, the information transfer protocol and the format of transmitted messages are also standardized.
In addition to receiving information about detected faults and the state of the engine management system, the on-board diagnostics system allows you to perform a number of verification tests by controlling the actuators.
The main component of the on-board diagnostics system is the ECM controller.
In addition to its main task (controlling the combustion processes of the fuel mixture), it performs self-diagnostics.
When performing this function, the controller monitors signals from various sensors and actuators of the ECM.
These signals are compared with the control values stored in the controller's memory.
If any signal goes beyond the control values, the controller evaluates this condition as a malfunction (for example, the voltage at the sensor output has become zero - a short circuit to ground), generates and writes the corresponding diagnostics to the error memory information, turns on the control lamp (indicator) of malfunctions, and also switches to emergency modes of operation of the ECM.
The on-board diagnostics system starts functioning from the moment the ignition is turned on and stops after the controller switches to the "standby" mode (occurs after the main relay is turned off).
The moment of activation of a particular diagnostic algorithm and its operation are determined by the corresponding engine operating modes. Diagnostic algorithms can be divided into three groups:
- 1) Diagnostics of sensors. The controller, monitoring the value of the sensor output signal, determines the presence or absence of a malfunction.
- 2) Diagnostics of the ECM actuators (driver diagnostics). The controller checks the control circuits for an open circuit, short circuit to ground or power source.
- 3) Diagnostics of the ECM subsystems (functional diagnostics).
The engine management system can be divided into several subsystems - ignition, fuel supply, idle speed maintenance, exhaust gas neutralization, gasoline vapor capture, etc.
Functional diagnostics provides a conclusion on the quality of their operation.
In this case, the system monitors not individual sensors or actuators, but parameters that characterize the operation of the entire subsystem as a whole.
For example, the quality of the ignition subsystem can be judged by the presence of misfires in the engine combustion chambers.
The fuel supply adaptation parameters provide information on the state of the fuel supply subsystem.
Each of the subsystems has its own requirements for the value of maximum permissible deviations of its parameters from average values.
Malfunction indicator
The malfunction indicator on Chevrolet Niva vehicles is located in the instrument cluster.
When the indicator is turned on, it means that the on-board diagnostic system has detected a malfunction in the ECM and the vehicle continues to move in emergency mode.
The blinking indicator indicates a malfunction that can lead to serious damage to the ECM components (for example, misfires can damage the catalytic converter).
When the ignition is turned on, the indicator should light up - this is how the ECM checks the serviceability of the indicator and its control circuit.
After starting the engine, the indicator should go out if the controller memory does not contain the conditions for its activation.
To protect against random, short-term errors that can be caused by loss of contact in electrical connectors or unstable engine operation, the indicator turns on after a certain period of time after the ECM malfunction is detected.
During this period, the on-board diagnostics system checks for the presence of a malfunction.
After eliminating the causes of the malfunction, the indicator will turn off after a certain delay time, during which the malfunction does not appear, and provided that there are no Other fault codes that require the indicator to be turned on.
DIAGNOSIS CODES FOR ME17.9.71
- P0030 Pre-catalyst heater circuit faulty
- P0031 Pre-catalyst heater control circuit short to ground
- P0032 Pre-catalyst heater control circuit short to electrical system
- P0036 Post-catalyst heater circuit faulty
- P0037 Post-catalyst heater control circuit short to ground
- P0038 Post-catalyst heater control circuit short to electrical system
- P0101 Circuit MAF Sensor Circuit Out of Range
- P0102 Mass Air Flow Sensor Circuit Low
- P0103 Mass Air Flow Sensor Circuit High
- P0112 Intake Air Temperature Sensor Circuit Low
- P0113 Intake Air Temperature Sensor Circuit High
- P0116 Coolant Temperature Sensor Circuit Out of Range
- P0117 Coolant Temperature Sensor Circuit Low
- P0118 Coolant Temperature Sensor Circuit High
- P0122 TPS A Circuit Low
- P0123 TPS A Circuit High
- P0130 Precatalyst Heated Oxygen Sensor malfunction
- P0131 Precatalyst HO2S Circuit Low Output
- P0132 Precatalyst HO2S Circuit High Output
- P0133 Precatalyst HO2S Circuit Slow Fuel Ratio Response
- P0134 Precatalyst HO2S Circuit Inactive
- P0135 Precatalyst HO2S Heater Malfunction
- P0136 Postcatalyst HO2S Malfunction
- P0137 Postcatalyst HO2S Circuit Low Voltage
- P0138 Postcatalyst HO2S Circuit High Voltage
- P0140 Postcatalyst HO2S Circuit inactive
- P0141 HO2S Heater Malfunction
- P0171 Fuel System Too Lean
- P0172 Fuel System Too Rich
- P0201 Cylinder 1 Injector Circuit Malfunction
- P0202 Cylinder 2 Injector Circuit Malfunction
- P0203 Cylinder 3 Injector Circuit Malfunction
- P0204 Cylinder 4 Injector Circuit Malfunction
- P0217 Engine Temperature Above Allowable
- P0222 TPS B Circuit Low Input
- P0223 TPS B Circuit High Input
- P0261 Injector Cylinder 1 Control Circuit Short to Ground
- P0262 Cylinder 1 Injector Control Circuit Short to Battery
- P0264 Cylinder 2 Injector Control Circuit Short to Battery
- P0265 Cylinder 2 Injector Control Circuit Short to Battery
- P0267 Cylinder 3 Injector Control Circuit Short to Battery
- P0268 Cylinder 3 Injector Control Circuit Short to Battery
- P0270 Cylinder 4 Injector Control Circuit Short to Battery
- P0271 Cylinder 4 Injector Control Circuit Short to Battery
- P0300 Random/Multiple Misfires Detected ignition
- P0301 Cylinder 1 Misfire Detected
- P0302 Cylinder 2 Misfire Detected
- P0303 Cylinder 3 Misfire Detected
- P0304 Cylinder 4 Misfire Detected
- P0327 Knock Sensor Circuit Low Voltage
- P0335 Crankshaft Position Sensor Circuit Malfunction
- P0340 Camshaft Position Sensor Malfunction
- P0351 Cylinder 1-4 Ignition Coil Control Circuit Open
- P0352 Cylinder 2-3 Ignition Coil Control Circuit Open
- P0363 Misfire Detected, Disabled Fuel delivery to non-running cylinders
- P0422 Catalyst efficiency below threshold
- P0441 Evaporative emission system, incorrect air flow through the Evaporative emission system
- P0444 Canister purge valve, open control circuit
- P0458 Canister purge valve, control circuit short to ground
- P0459 Canister purge valve, control circuit short to electrical system
- P0480 Fan relay 1, open control circuit
- P0481 Fan relay 2, open control circuit
- P0500 Vehicle speed sensor malfunction
- P0501 Vehicle speed sensor, signal out of acceptable range
- P0504 Brake pedal A/B switches, signal mismatch
- P0532 A/C pressure sensor, low signal level
- P0533 A/C pressure sensor, high signal level
- P0560 Vehicle system voltage
- P0561 Vehicle system voltage unstable
- P0562 Vehicle system voltage, low level
- P0563 Vehicle system voltage, high level
- P0606 ECM controller, ADC malfunction
- P0615 Aux. starter relaya, open control circuit
- P0616 Additional starter relay, control circuit short to ground
- P0617 Additional Starter Relay, Control Circuit Short to Battery
- P0627 Fuel Pump Relay, Control Circuit Open
- P0628 Fuel Pump Relay, Control Circuit Short to Ground
- P0629 Fuel Pump Relay, Control Circuit Short to Battery
- P0645 A/C Compressor Clutch Relay, Control Circuit Open
- P0646 A/C Compressor Clutch Relay, Control Circuit Short to Ground
- P0647 A/C Compressor Clutch Relay, Control Circuit Short to Battery
- P0691 Fan Relay 1, Control Circuit Short to Ground
- P0692 Fan Relay 1, Control Circuit Short to Battery
- P0693 Fan Relay 2, Control Circuit Short to ground
- P0694 Fan relay 2 control circuit short to battery
- P0830 Clutch pedal switch circuit malfunction
- P1335 Throttle actuator control (TAC) monitor, throttle position out of range
- P1336 Throttle actuator control (TAC) monitor, throttle position sensor "A" / "B" signal mismatch
- P1388 Throttle actuator control (TAC) monitor, throttle position sensor "A" / "B" signal mismatch
- P1389 Throttle actuator control (TAC) monitor, engine speed out of range
- P1390 Throttle actuator control (TAC) monitor, incorrect response to a system malfunction
- P1391 Throttle actuator control monitoring, no response to a system malfunction
- P1545 Throttle actuator, valve position out of acceptable range
- P1558 Throttle actuator, return spring faulty
- P1559 Throttle actuator, valve rest position out of acceptable range
- P1564 Throttle actuator control system, valve zero position adaptation interrupted due to low on-board voltage
- P1570 Immobilizer, circuit faulty
- P1578 Throttle actuator control system, zero position adaptation value out of acceptable range
- P1579 System throttle actuator control module, zero point adaptation interrupted due to external conditions
- P1602 ECM controller, power supply loss
- P1603 Throttle actuator control monitoring module malfunction
- P2100 Throttle actuator motor control circuit open
- P2101 Throttle actuator motor control circuit malfunction
- P2122 Pedal position sensor A circuit low
- P2123 Pedal position sensor A circuit high
- P2127 Pedal position sensor B circuit low
- P2128 Pedal position sensor B circuit high
- P2135 Sensors "A" / "B" throttle position, signal mismatch
- P2138 Sensors "A" / "B" accelerator pedal position, signal mismatch
- P2176 Throttle actuator control system, adaptation of the valve zero position not performed
- P2187 Fuel injection system too lean at idle
- P2188 Fuel injection system too rich at idle
- P2301 Ignition coil cylinder 1-4, control circuit short to on-board network
- P2304 Ignition coil cylinder 2-3, control circuit short to on-board network
When clearing (deleting) fault codes from the controller memory using diagnostic equipment, the indicator goes out.