Below are the general methods for checking the integrity of electrical circuits, checking for short circuits using an ohmmeter and voltmeter
Checking the integrity of an electrical circuit
Loss of integrity of an electrical circuit can be caused by the following reasons:
- - disconnection of the harness block;
- - poor connection of the harness block;
- - contamination, oxidation, corrosion of contacts;
- - deformation of contacts;
- - damage to the wire.
Check the integrity of the circuit in the following sequence:
Disconnect the terminal of the "ground" wire from the battery.
Visually check that the harness blocks are connected on both sides of the electrical circuit, the locks of the retainers snapped.
Disconnect the pads, visually check the contacts for dirt, corrosion, deformation.
Pull the wires near the pad to make sure that the wire and terminal are tightly crimped, that the terminal is fixed inside the pad.
Using a probe of the specified diameter and length corresponding to the size of the contact in the mating pad, make sure that the terminals of the harness pads provide a reliable connection (the terminals are not recessed into the pad, the probe fits tightly into the terminal).
Using an ohmmeter, measure the resistance of the circuit between the pads.
The resistance of a serviceable circuit should be less than 1 Ohm.
To avoid damaging the terminals, it is permissible to use probes of the specified diameter corresponding to the size of the contacts in the mating pads for measurements.
Checking the short circuit on "mass"
Perform the check in the following sequence:
Disconnect the pads on both sides of the electrical circuit.
Connect the tester, with one end connected to the "+" of the battery, to the terminal of the circuit being checked. If the tester lights up, the circuit being tested is shorted to ground.
To avoid damaging the terminal, the tester must be connected using a probe of a specified diameter that matches the size of the contact in the mating connector.
Checking the circuit for shorting to the vehicle's electrical system
Perform the check in the following sequence:
Disconnect the connector on one side of the electrical circuit.
Connect one end of the tester to ground and connect it to the terminal of the circuit being tested.
If the tester lights up, the circuit being tested is shorted to the vehicle's electrical system.
Connect the disconnected connector.
Disconnect the connector on the other side of the electrical circuit.
To avoid damaging the terminal, the tester must be connected using a probe of a specified diameter that matches the size of the contact in the mating connector. block.
Measuring the voltage on the contacts of the wiring harness
Check in the following order:
Disconnect the block on one side of the electrical circuit.
Connect the positive cord of the voltmeter to the terminal of the circuit being checked, and the negative cord to the vehicle's ground. Record the voltage value.
To avoid damaging the terminal, the positive lead of the voltmeter must have a probe of the specified diameter corresponding to the size of the contact in the mating socket.
Preliminary Checks
Before performing the checks described below, it is necessary to perform the "Diagnostic Circuit Check".
When diagnosing, repairing or searching for the cause of a malfunction, it is always necessary to thoroughly inspect the underhood space.
All vacuum hoses must be checked for pinching, cuts or disconnection.
All electrical wiring located in the underhood space must be checked for secure connections, the absence of burnt, frayed or deformed wires, the absence of wire contact with sharp edges or the exhaust manifold.
Be sure to check the ground wire contacts for contamination and a secure connection with "mass".
Checks before starting
Check the ECM connections for secure contacts and correct connection. Pay special attention to the power and ground circuits.
Check the vacuum hoses for damage and kinks, correct connections and tightness.
Check the air intake system for leaks.
Check the high-voltage wires for cracks and carbon tracks.
Check the wiring for secure connections and no damage to the wires.
Intermittent malfunctions
If a malfunction causes the on-board diagnostics to be triggered, troubleshooting should begin with an analysis of the information recorded in the controller's error memory.
This information can be read using a diagnostic tool. To do this, select the mode: "Fault codes; Stored data".
The most useful parameters are:
- - DLC - delay before deleting information about a fault that is no longer active from the controller's error memory.
- - "active / inactive" icon malfunction (currently)";
- - HZ - how many times this malfunction was recorded by on-board diagnostics;
- - ECM operating conditions under which the malfunction occurred.
The initial value of the DLC parameter is 40. If the malfunction has become inactive, then with each engine warm-up cycle the DLC parameter value decreases by 1.
Therefore, with its help, you can determine how many warm-up cycles have passed since the malfunction disappeared until the diagnostics were performed.
It makes sense to search for intermittent malfunctions if at the time of diagnostics the DLC parameter value is > 38.
Using the "active / inactive malfunction" icon, you can track the behavior of the malfunction when performing any manipulations.
The HZ parameter shows how intermittent the nature of this malfunction is. malfunction.
The operating conditions of the ECM are characterized by a set of parameters that allow you to determine the engine operating modes in which the malfunction occurs.
Step 1
Finding faults that are intermittent in nature should begin with checking the problematic electrical circuits.
When checking electrical circuits, pay attention to the following:
- - the terminals are securely crimped on the wire, but the wires are not pinched;
- - the terminals are securely fixed in the block;
- - the terminals are not deformed;
- - there is no dirt, moisture, or corrosion on the terminals;
- - the block housing does not contain any signs of damage (cracks, deformation, melting);
- - there is a serviceable rubber seal in the block housing seal;
- - terminals provide a reliable connection. To do this, it is necessary to check all the terminals in the problematic circuits using a probe of a given diameter and length (make sure that the terminals are not recessed into the block, the probe fits tightly into the terminal);
- - there is no damage to the insulation in the wires;
- - there are no kinks in the wires inside the insulation.
If intermittent faults occur, it is always necessary to check the integrity of the "ground" circuits of the engine management system (see Checking the integrity of the electrical circuit).
It is necessary to make sure that the "ground" terminals are securely fastened to the car body, the terminals of the power and "ground" wires are securely fastened to the battery.
If the error code P1602 is recorded in the controller's memory, it is necessary to check the power supply circuits of the controller, paying attention to the following:
- - the fuses are in good condition and securely fastened in pads;
- - the main relay is in good condition and securely fastened in the pad.
If the above checks did not reveal a malfunction, proceed to step 2.
Step 2
On a vehicle with the engine running, it is necessary to move the wires, starting from the connectors, along the entire harness route, monitoring the behavior of the control system by ear or using a diagnostic device.
If the check did not reveal a malfunction, proceed to step 3.
Step 3
Based on the freeze frame information, it is necessary to reproduce the vehicle driving modes in which the malfunctions were recorded. In this case, it is necessary to monitor the operating parameters of the engine management system using a diagnostic tool.
Difficult engine starting
Signs: the crankshaft turns normally, but the engine does not start for a long time and may stall immediately after starting.
Carefully perform the visual/physical checks described at the beginning of this section.
Carry out diagnostics of the ECM according to the A-3 chart.
Carry out maintenance of the spark plugs.
Measure the compression.
Unstable operation or stalling at idle
Signs:
- - the engine runs unevenly at idle;
- - increased engine vibration.
In addition, the idle speed may fluctuate running.
Both defects in extreme cases can cause the engine to stop.
Carry out visual/physical checks carefully.
Run diagnostics of the ECM according to the A-3 chart.
Check the injector balance according to the C-3 chart.
Carry out maintenance of spark plugs.
Measure the compression.
Jerking or dips in engine operation
Signs:
- - fluctuations in engine power with a constant throttle position or speed;
- - a feeling of the car accelerating and braking without changing the position of the accelerator pedal.
Carry out visual/physical checks described at the beginning of this section carefully.
Check the system ignition.
Check the fuel supply system.
Carry out maintenance of spark plugs.
Carry out a trial replacement of the DDTV.
Insufficient engine power and responsiveness
Signs:
- - the engine develops power lower than expected;
- - no or insufficient increase in speed when pressing the pedal accelerator.
Carry out visual/physical checks thoroughly.
Check the fuel supply system.
Test the replacement of the DDTV.
Measure the compression.
Increased fuel consumption
Increased fuel consumption is a consequence of ECM malfunctions, which, when eliminated, normalize fuel consumption.
Diagnostic codes for the M86 controller
Code - Description
- P0030 Heater of the DA before the neutralizer, the circuit is faulty
- P0031 Heater of the DA before the neutralizer, the control circuit short to ground
- P0032 Heater of the DA before the neutralizer, the short to ground control circuit to system power
- P0036 After Catalytic Converter Heater Circuit Malfunction
- P0037 After Catalytic Converter Heater Control Circuit Short to Ground
- P0038 After Catalytic Converter Heater Control Circuit Short to System Power
- P0106 Intake Air Pressure Sensor Circuit Out of Range
- P0107 Intake Air Pressure Sensor Circuit Low Voltage
- P0108 Intake Air Pressure Sensor Circuit High Voltage
- P0111 Intake Air Temperature Sensor Circuit Out of Range
- P0112 Intake Air Temperature Sensor Circuit Low Voltage signal
- P0113 Intake Air Temperature Sensor Circuit High Voltage
- P0116 IAT Circuit Out of Range
- P0117 IAT Circuit Low Voltage
- P0118 IAT Circuit High Voltage
- P0122 TPS A Circuit Low Voltage
- P0123 TPS A Circuit High Voltage
- P0130 Pre-catalyst Heated Oxygen Sensor Malfunction
- P0131 Pre-catalyst Heated Oxygen Sensor Circuit Low Output Voltage
- P0132 Pre-catalyst Heated Oxygen Sensor Circuit High Output Voltage
- P0133 Pre-catalyst Heated Oxygen Sensor Circuit Before Catalyst, Slow Response to Air-Fuel Ratio Changes
- P0134 Before Catalyst HO2S Circuit Inactive
- P0135 Before Catalyst HO2S Heater Malfunction
- P0136 After Catalyst HO2S Malfunction
- P0137 After Catalyst HO2S Circuit Low Voltage
- P0138 After Catalyst HO2S Circuit High Voltage
- P0140 After Catalyst HO2S Circuit Inactive
- P0141 After Catalyst 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 Limit
- P0222 TPS B Circuit Low Input
- P0223 TPS B Circuit High Input
- P0261 Cylinder 1 Injector Control Circuit Short to Ground
- P0262 Cylinder 1 Injector Control Circuit Short to Battery
- P0264 Cylinder 2 Injector Control Circuit Short to Ground
- 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
- P0301 Cylinder 1 Misfires Detected
- P0302 Cylinder 2 Misfires Detected ignition
- P0303 Cylinder 3 Misfire Detected
- P0304 Cylinder 4 Misfire Detected
- P0327 Knock Sensor Circuit Low Input
- P0328 Knock Sensor Circuit High Input
- P0335 Crankshaft Position Sensor Circuit Malfunction
- P0336 Crankshaft Position Sensor Circuit Signal Out of Range
- P0340 Camshaft Position Sensor (CMP) Malfunction
- P0342 Camshaft Position Sensor (CMP) Circuit Low Input
- P0343 Camshaft Position Sensor (CMP) Circuit High Input signal
- P0351 Ignition coil 1 control circuit open
- P0352 Ignition coil 2 control circuit open
- P0353 Ignition coil 3 control circuit open
- P0354 Ignition coil 4 control circuit open
- P0363 Misfire detected, fuel supply to non-firing cylinders cut off
- P0422 Catalyst efficiency below threshold
- P0441 Evaporative emission system, incorrect air flow through the Evaporative emission system
- P0443 Canister purge valve, circuit malfunction
- P0444 Canister Purge Valve Control Circuit Open
- P0458 Canister Purge Valve Control Circuit Short to Ground
- P0459 Canister Purge Valve Control Circuit Short to Battery
- P0480 Fan Relay 1 Circuit Malfunction
- P0481 Fan Relay 2 Circuit Malfunction
- P0504 Brake Pedal A/B Switches Signal Mismatch
- P0513 Immobilizer Key Incorrect
- P0522 Oil Pressure Sensor Circuit Low Voltage
- P0523 Oil Pressure Sensor Circuit High Voltage
- P0560 Vehicle Voltage
- P0561 Vehicle Voltage Unstable
- P0562 Vehicle Voltage Low
- P0563 Vehicle Voltage High
- P0601 ECM Controller ROM Checksum Error
- P0603 ECM Controller Internal RAM Error
- P0604 ECM Controller External RAM Error
- P0606 ECM Controller Processor Error
- P0627 Fuel Pump Relay Circuit Malfunction
- P0628 Fuel Pump Relay Control Circuit Short to Ground
- P0629 Fuel Pump Relay Control Circuit Short to Battery network
- P062F Internal EEPROM Error
- P0641 Sensor Power Circuit Open
- P0642 Sensor Power Circuit Low
- P0643 Sensor Power Circuit High
- P0645 A/C Compressor Clutch Relay Circuit Malfunction
- P0646 A/C Compressor Clutch Relay Control Circuit Short to Ground
- P0647 A/C Compressor Clutch Relay Control Circuit Short to Battery
- P0660 Intake System Run Length Control Valve Open Circuit
- P0661 Intake System Run Length Control Valve Control Circuit Short to Ground
- P0662 Intake System Run Length Control Valve short circuit 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
- P1301 Cylinder 1 critical catalytic converter misfire detected
- P1302 Cylinder 2 critical catalytic converter misfire detected
- P1303 Cylinder 3 critical catalytic converter misfire detected
- P1304 Cylinder 4 misfire detected ignition faults critical to the catalyst
- P1335 Throttle actuator control monitoring, throttle position out of range
- P1336 Throttle actuator control monitoring, throttle position sensor "A" / "B" signal mismatch
- P1388 Throttle actuator control monitoring, accelerator pedal position sensor "A" / "B" signal mismatch
- P1389 Throttle actuator control monitoring, engine speed out of range
- P1390 Throttle actuator control monitoring, incorrect response to a system malfunction
- P1391 Throttle actuator control monitoring, throttle actuator, no response to system malfunction
- P1545 Throttle actuator, throttle position out of range
- P1558 Throttle actuator, return spring faulty
- P1559 Throttle actuator, throttle valve resting position out of range
- P1564 Throttle actuator control system, throttle valve zero position adaptation interrupted due to low battery voltage
- P1570 Immobilizer circuit faulty
- P1578 Throttle actuator control system, zero position adaptation value out of range
- P1579 Throttle actuator control system, throttle valve zero position adaptation interrupted due to external conditions
- P1602 ECM power supply loss
- P1640 ECM EEPROM read/write error
- P2100 Throttle actuator control circuit open
- P2101 Throttle actuator control circuit malfunction
- P2102 Throttle actuator control circuit short to ground
- P2103 Throttle actuator control circuit short to battery
- P2122 Pedal position sensor A circuit low
- P2123 Pedal position sensor A circuit high
- P2127 Pedal position sensor B circuit low signal
- P2128 Pedal Position Sensor B Circuit High
- P2135 Throttle Position Sensors A/B Signal Mismatch
- P2138 Sensors A / "B" accelerator pedal position, signal mismatch
- P2176 Throttle actuator control system, zero position adaptation of the valve not performed
- P2187 Fuel injection system too lean at idle
- P2188 Fuel injection system too rich at idle
- P2270 Ignition coil after the neutralizer, no response to rich mixture
- P2271 Ignition coil after the neutralizer, no response to lean mixture
- P2301 Ignition coil cylinder 1, control circuit short to battery
- P2304 Ignition coil cylinder 2, control circuit short to battery
- P2307 Ignition coil cylinder 3, short circuit in control circuit to electrical system
- P2310 Ignition coil 4, short circuit in control circuit to electrical system
- U0001 CAN bus fault
- U0002 CAN bus, general fault
- U0009 CAN bus, short circuit from L line to H line
- U0073 CAN bus disconnected
- U0121 CAN bus, no data from ABS controller
- U0122 CAN bus, no data from ESP controller
- U0155 CAN bus, no data from instrument cluster
- U0167 CAN bus, no communication with immobilizer
- U0415 CAN bus, invalid data from ABS controller
- U0416 CAN bus, invalid data from ESP controller
- U0426 CAN bus, invalid data from immobilizer
