Variator diagnostics (Mitsubishi Lancer 9)

Troubleshooting

Note:

• CVT faults may be caused by improper maintenance, improper adjustment or faulty electronic CVT control system, mechanical fault, faulty hydraulic CVT control system, insufficient engine power or a combination of these faults. Therefore, before starting the inspection, it is necessary to determine the area of the fault (engine, control system or gearbox).
• Troubleshooting should begin with the simplest operations and proceed in order of increasing complexity.

1. Check for signs of CVT malfunction and the conditions under which they occur.

2. Read diagnostic trouble codes. Write down the trouble codes and delete the codes from the memory of the electronic control unit of the engine and variator.

3. Perform basic checks and adjustments (checking tire pressure, checking the level and condition of the working fluid in the variator, checking the variator control mechanism, etc.) for which deviations from the norm can be easily determined.

Note: Analysis of the results of checking the working fluid level:

• If the working fluid level in the variator is below normal, the working fluid pump will capture the working fluid along with air, which will lead to various malfunctions. Air bubbles that get into the variator hydraulic system are the cause of foaming of the working fluid.
• If the working fluid level is higher than normal, then there will be excessive foaming of the working fluid, which will ultimately lead to the same consequences as in the case of a low working fluid level, and will cause premature deterioration of the working fluid.
• In both cases, air bubbles cause overheating, oxidation of the working fluid and deposition of varnish, which disables valves, clutches and actuators. Foaming also leads to the release of working fluid through the breather of the variator crankcase, which is mistaken for leaks.

4. Perform road tests to determine if further CVT diagnostics are needed.



a) Check the correctness of gear shifting. If gear shifting is normal, then check the electrical part of the control system.

b) Make sure that the fault is confined to the CVT. If there is noise or vibration, possible sources may be the compressor, engine, driveshaft, etc.

5. Read diagnostic trouble codes (again).

a) If fault codes are output when a malfunction symptom is present or fault codes were output previously (but fault codes are not present after road tests), see the subsection "Troubleshooting by diagnostic codes".

b) If there are no fault codes (before and after road tests), but there is a malfunction symptom, then see the subsection "Troubleshooting by their symptoms".

6. If the possible cause is a malfunction in the electronic CVT control system, then use a tester or oscilloscope to check the input and output signals of the electronic CVT control unit.

a) If there are incorrect input and output signals from the electronic control unit of the variator, check the wiring according to the corresponding electrical diagram.

b) If no fault is found when checking the electrical wiring, then check the individual components of the system.

7. If the signals from the electronic control system are normal or if a malfunction in the CVT hydraulic control system is a possible cause, check the pressure in the CVT hydraulic control system. If the condition of the hydraulic system differs from normal, perform the appropriate checks and adjustments (see section "Checking the CVT control system").



8. If the pressure in the CVT control hydraulic system is normal or if the possible cause is a malfunction in the main CVT system (mechanical part), then check the engine and torque converter with the vehicle fully braked, identify the faulty part and make the necessary repairs.

9. After completing the repair, perform a road test to ensure that the problem has been corrected.

Reading diagnostic trouble codes

Note: Use the "CVT Control System Fault Codes" table to identify fault codes.

1. Prepare the vehicle for inspection as follows.

a) Make sure that the battery is in good condition, as fault detection is impossible if the battery voltage is low.

b) Turn off all additional equipment.

c) Set the variator selector to the "N" position.

Caution: Do not disconnect the battery until the diagnostic results have been fully read, as the fault code will be cleared from the ECU memory when the battery or ECU connector is disconnected.

Table. Error codes of the CVT control system.

2. Turn the ignition switch to the "OFF" position.



3. When checking with a tester:

a) Connect the tester to the diagnostic connector under the instrument panel.

Caution: When connecting or disconnecting the tester, the ignition must be switched off (ignition key in the "OFF" position).

b) Turn on the ignition and select the CVT control system test mode on the tester.



4. Reading codes without using a tester (using the "N" range indicator).

a) Use a special tool to connect to ground.



b) Turn on the ignition and read the fault codes by observing the number of flashes of the "N" range indicator on the instrument cluster.

Note:

• The fault code consists of two digits, the first digit is determined by the initial series of flashes, then after a pause of 2 seconds, a second series of flashes follows, which corresponds to the second digit of the code.
• If there are two or more fault codes, the lowest code will be displayed first, followed by the others in ascending order. There will be a 3-second pause between codes.
• The figure shows an example of the output of the codes "13" and "33".

c) If there is no malfunction, the indicator will flash at 0.5 second intervals (normal status code).





5. After completing the check, turn the ignition switch to the "OFF" position and then disconnect the tester or special tools from the diagnostic connector.

Clearing diagnostic trouble codes

1. Turn the ignition switch to the "OFF" position.

2. If a tester is used, connect it to the diagnostic connector and erase the codes.

3. When the tester is not in use, disconnect the cable from the negative terminal of the battery for 10 seconds or more.

(The article is reprinted from a web resource: «MitsubishiMan»)

Caution: After disconnecting the wire from the negative terminal of the battery, the contents of the memory of the electronic control units of other systems will be lost.

4. After warming up the engine, let it idle for at least 15 minutes.

Explanations on the operation of the self-diagnostic system

1. Indication of the variator status using the "N" range indicator.

a) If the "N" range indicator (indicated by the arrow) on the instrument cluster flashes at a frequency of 1 time per second (1 Hz), this means that the self-diagnostic system has detected a malfunction in the CVT drive pulley speed sensor, the CVT driven pulley speed sensor, any electromagnetic valve, the working fluid pressure and temperature sensors or relay and the system is operating in emergency mode.

Table. Checking the voltage at the terminals of the electronic control unit of the engine and variator.

b) In this case, it is necessary to check the diagnostic trouble codes.

Attention: if the indicator flashes at a frequency of 2 times per second (2 Hz), this indicates an increased temperature of the working fluid in the variator, so stop the car in a safe place and let the engine idle until the indicator goes out.

Checks on the connector of the electronic control unit of the engine and variator

Note:

• If any deviation from the nominal value is detected, check the corresponding sensor, actuator and wires.
• After repairing or replacing the unit, retest to ensure that the problem has been corrected.

Follow the table "Checking the voltage at the terminals of the electronic control unit of the engine and variator"

1. Disconnect the control unit connector and connect the test lead harness between the connectors or use the voltmeter needle probes to test at the connector on the harness side.

Caution: A short circuit of the positive voltmeter probe connected to the connector terminal to ground may cause damage to the wiring, sensor, electronic control unit, or all of the above.

2. With the control unit connector connected, measure the voltage between the control unit ground terminals and each corresponding terminal of the control unit connector.