Air Bag Systems
CONNECTOR CONSTRUCTIONThe connector of the SRS diagnosis unit has a double lock mechanism, fit verification mechanism and connector shorting mechanism.
DOUBLE LOCK MECHANISM
The mechanism is composed of two mechanisms: Each connector of the SRS diagnosis unit is locked to the connector of the harness, then these connectors (of the four harnesses) are locked with the secondary lock lever mounted on the connector of the SRS diagnosis unit side.
The secondary lock lever locking is done as the lock spring fits in the notch of the connector.
The operating principle is described below.
WHEN CONNECTORS ARE TO BE FITTED
(1) The SRS diagnosis unit and harness side connectors are connected. (Primary lock)
(2) The secondary lock lever mounted to the SRS diagnosis unit side connector, is pressed down until a click is heard indicating that the connectors have been locked. (Secondary lock)
If the harness and SRS diagnosis unit connectors do not properly fit, the secondary lock lever side projection and the harness side connector projection interfere with each other, making it impossible to lock the connectors.
WHEN CONNECTORS ARE UNLOCKED
(1) Release the lock of SDU connector in accordance with the following procedure:
In case that there is no notch on the lock lever (Type 1)
Place a flat tip screwdriver against the lock spring (metal section) of the connector lock lever as shown in the illustration, and push the spring horizontally toward the inside of the unit.
Caution:
1. Do not use excessive force to raise the lock lever.
2. Do not insert the screwdriver into the gap between the lock lever and the lock spring.
In case that there is a notch on the lock lever (Type 2)
Place a flat tip screwdriver against the lock spring (metal section) at the lock lever notch as shown in the illustration, and push the spring toward the unit.
Caution: Do not use excessive force to raise the lock lever.
(2) Press the primary lock of each of the harness side connectors and remove the harness side connector.
FIT VERIFICATION MECHANISM
The mechanism is used to electrically check the engagement of the connector between the SRS diagnosis unit and the body wiring harness. The operating principle is described below.
(1) Securely connect the SRS diagnosis unit and harness side connectors and press the secondary lock lever down to lock the connectors.
(2) At this time, the short bar provided on the rear surface of the secondary lock lever produces a short circuit across terminals No. (7) and (8) of the SRS diagnosis unit. The SRS diagnosis unit supplies monitoring current to the circuit to electrically verify that the connectors have been locked.
CONNECTOR SHORTING MECHANISM
The mechanism is designed for prevention of accidental ignition of the inflator when the clock spring connector (for the squib circuit) is removed from the SRS diagnosis unit. The operating principle is described below.
WHEN CONNECTORS ARE FITTED
When the SRS diagnosis unit and clock spring connectors are coupled, the circuit between the short terminals and clock spring connector terminals is kept in the OFF state by the partition plate provided in the connector of the SRS diagnosis unit.
WHEN CONNECTORS ARE DISCONNECTED
When the clock spring connectors are disconnected from the SRS diagnosis unit, the partition plate between the short terminals and clock spring connector terminals is removed. As a result, a short circuit is formed between the two poles of the clock spring connector terminals to prevent generation of a potential difference (current) between the squib terminals.