Diagnostic Strategies
CONNECTOR MEASUREMENT SERVICE POINTSTurn the ignition switch to "OFF" when connecting and disconnecting the connectors. Turn the ignition switch to "ON" when measuring it there are no instructions to the contrary.
IF INSPECTING WITH THE CONNECTOR CONNECTED (WITH CIRCUIT IN A CONDITION OF CONTINUITY)
Required Special Tools:
MB991222: Prove (Contained in MB991223 Harness Set)
MD998459: Test Harness
Waterproof Connectors
Be sure to use special tool, MB991219. Never insert a test probe from the harness side, as this so will reduce the waterproof performance and result in corrosion.
Ordinary (non-waterproof) Connectors
Check by inserting the test probe from the harness side. Note that if the connector (control unit, etc.) is too small to permit insertion of the test probe, it should not be forced; use special tool, MB991222 for this purpose.
IF INSPECTING WITH THE CONNECTOR DISCONNECTED [When Inspecting a Female Pin][
Required Special Tool:
MB991219: Inspection Harness (Contained in MB991223 Harness Set) Use special tool, MB991219.
The inspection harness for connector pin contact pressure should be used. The test probe should never be forcibly inserted, as it may cause a defective contact.
[When Inspecting a Male Pin]
CAUTION: At this time, be careful not to short the connector pins with the test probes. To do so may damage the circuits inside the ECU.
Touch the pin directly with the test bar.
CONNECTOR INSPECTION SERVICE POINTS VISUAL INSPECTION
- Connector is disconnected or improperly connected
- Connector pins are pulled out
- Due to harness tension at terminal section
- Low contact pressure between male and female terminals
- Low connection pressure due to rusted terminals or foreign matter lodged in terminals
CONNECTOR PIN INSPECTION
If the connector pin stopper is damaged, the terminal connections (male and female pins) will not be perfect even when the connector body is connected, because the pins may pull out of the back side of the connector. Therefore, gently pull the wires one by one to make sure that no pins pull out of the connector.
CONNECTOR ENGAGEMENT INSPECTION
Required Special Tool:
MB991219: Inspection Harness (Contained in MB991223 Harness Set)
Use special tool, MB991219, to inspect the engagement of the male pins and female pins. [Pin drawing force: 1 N (0.2 pound) or more]
HOW TO COPE WITH INTERMITTENT MALFUNCTIONS
Most intermittent malfunctions occur under certain conditions. If those conditions can be identified, the cause will be easier to find.
TO COPE WITH INTERMITTENT MALFUNCTION;
1. Ask the customer about the malfunction Ask what it feels like, what it sounds like, etc. Then ask about driving conditions, weather, frequency of occurrence, and so on.
2. Determine the conditions from the customer's responses. Typically, almost all intermittent malfunctions occur from conditions like vibration, temperature and/or moisture change, poor connections. From the customer's replies, it should be reasoned which condition is influenced.
3. Use simulation test
In the cases of vibration or poor connections, use the simulation tests below to attempt to duplicate the customer's complaint. Determine the most likely circuit(s) and perform the simulation tests on the connectors and parts of that circuit(s). Be sure to use the inspection procedures provided for diagnostic trouble codes and trouble symptoms.
For temperature and/or moisture conditions related intermittent malfunctions try to change the conditions of the suspected circuit components, then use the simulation tests below.
4. Verify the intermittent malfunction is eliminated
Repair the malfunctioning part and try to duplicate the condition(s) again to verify the intermittent malfunction has been eliminated.
SIMULATION TESTS
NOTE: In case of difficulty finding the cause of the intermittent malfunction, the data recorder function in the scan tool is effective.
For these simulation tests, shake, then gently bend, pull, and twist the wiring of each of these examples to duplicate the intermittent malfunction.
- Shake the connector up-and-down, and right-and-left.
- Shake the wiring harness up-and-down, and right-and-left.
- Vibrate the part or sensor.
HARNESS CONNECTOR INSPECTION / CONNECTOR CONTINUITY AND VOLTAGE TEST
Required Special Tools:
MB991219: Test Harness Set
MD998459: Test Harness
Follow the steps below to avoid causing poor connector contact and/or reduced waterproof performance of connectors when checking continuity and/or voltage at connectors of waterproof connectors.
CAUTION: Never back probe a waterproof connector. Back probing a connector may cause the terminals to corrode, deteriorating circuit performance.
1. If checking is performed with the circuit in the state of continuity, be sure to use the special tool MD9918459.
CAUTION: Forcing the probe into the terminal may open the terminal causing intermittent or poor contact creating an open circuit.
2. If the connector is disconnected for checking and the facing part is the female pin side, the harness for checking the contact pressure of connector pins should be used.
CAUTION: Do not simultaneously contact more than one terminal with the probe. Contacting two or more terminals at the same time may damage a circuit, possibly to the point of starting an electrical fire.
3. If the facing part is the male pin side, contact the test probe directly to the pins.
IMPROPER TERMINAL ENGAGEMENT CHECK
Terminals inside a connector may not engage properly even through the connectors do.
Make sure that each terminal does not come out of the connector when pulling each harness wire. If it does, repair or replace the connector.
CONNECTOR TERMINAL ENGAGEMENT AND DISENGAGEMENT
Loosely engaged terminals can be repaired by removing the female terminal from the connector housing and raising its lance to establish better engagement. Removal of the connector terminal used for MFI and INVECS-II control circuit can be done in the following manner.
COMPUTER CONNECTOR
1. Insert a screwdriver [1.4 mm (0.06 inch) width] as shown in the figure, disengage front holder, and remove it.
2. Push the harness wire of the terminal to be repaired deep into the connector from the harness side and hold it there.
3. Insert the tip of the screwdriver [1.4 mm (0.06 inch) width] into the connector as shown in the figure, raise the housing lance slightly with the tip, and pull out the terminal.
NOTE: Tool number 753787-1 supplied by AMP can be used instead of screwdriver
4. Insert a needle through the hole provided on the terminal and raise the contact point. Lightly squeeze the outer edge so the flats are parallel with the bottom.
ROUND WATERPROOF CONNECTOR
1. Remove the waterproof cap by using a screwdriver.
2. Insert the tip of the screwdriver [1.4 mm (0.06 inch) or 2.0 mm (0.08 inch) width] into the connector as shown in the figure, raise the housing lance slightly with the tip, and pull out the terminal.
3. Insert a screwdriver through the hole provided on the terminal and raise the contact point. Lightly squeeze the outer edge so the flats are parallel with the bottom.
RECTANGULAR WATERPROOF CONNECTOR
1. Disengage the front holder by using a screwdriver and remove it.
2. Insert the tip of a screwdriver [*0.8 mm (0.03 inch) width] into the connector as shown in the figure, push it lightly to raise the housing lance, and pull out the terminal.
* If the right size screwdriver is not available, convert a conventional driver to the proper size.
3. Press the contact point of the male terminal down by holding a screwdriver [1.4 mm (0.06 inch) width] as shown in the figure. Lightly squeeze the outer edge so the flats are parallel with the bottom.
INJECTOR CONNECTOR
1. Remove the waterproof cap.
2. Insert the tip of a screwdriver [1.4 mm (0.06 inch) width] into the connector as shown in the figure, press in the terminal lance, and pull out the terminal.
CAUTION: Make sure the lance is in the proper condition before the terminal is inserted into the connector.
3. Press the contact point of the male terminal down by holding a screwdriver [1.4 mm (0.06 inch) width] as shown in the figure.