Interpretation ID: nht88-1.7

TYPE: INTERPRETATION-NHTSA

DATE: 01/01/88 (EST)

FROM: PAUL RENEAU

TO: U.S. DEPARTMENT OF TRANSPORTATION NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION

TITLE: NONE

ATTACHMT: ATTACHED TO LETTER DATED 08/26/88 TO PAUL A. RENEAU FROM ERIKA Z. JONES, REDBOOK A32, STANDARD 118

TEXT: Dear Engineer:

Would you please review the following information and inform me as to whether the design of the power-operated window system described and specified meets rule no. 118, titled "Power-Operated Window Systems" as amended in 1983.

SPECIFICATION: As per rule no. 118, S1 in the schematic corresponds to the ignition key switch. S1 is closed in the "ON" or "ACCESSORY" position. Closing S1 activates transistor Q1 which deactivates transistor Q2. Q2 supplies voltage/current to transi stors Q3 and Q4. Q3 drives power relay K1 and Q4 drives power relay K2. Both relays have normally open contacts which supply voltage to drive electric window and/or partition motors. With S1 in the "ON" or "ACCESSORY" position, normal power window and /or partition function exists. When the key that controls S1 is returned to the "OFF" position, Q1 is deactivated after capacitor C1 discharges through resistor R1 for a time period determined by RC timing circuit; D1, C1, R1 and Q1. Q2 is activated upo n deactivation of Q1 and supplies voltage/current to Q3 and Q4. Q3 is driven by RC timing circuit; C2, R3 for a time period determined by the values of C2 and R3. Q3, as stated, drives normally-open relay K1 which in turn drives electric motor M1. Q4 operates in a similar manner driving motor M2. Upon deactivation of Q3 and Q4, relays K1 and K2, and consequently, motors M1 and M2 are deactivated. With R3 and R4 as potentiometers, the corresponding motor activation can be adjusted for only as long a s required to close the said window and/or partition. S2 is closed when either front door is opened. This switch (es) corresponds to switches currently used on vehicle door posts to activate interior/courtesy lights and the door-ajar indicator. These switches are widely used and proven reliable in the industry. Opening either front door closes switch S2 and short circuits the RC timing circuits driving K1 and K2 thus instantaneously stopping motors M1 and M2. The said circuits are reactivated ONLY by closing S1 which requires that the key be in the ignition and in the "ON" or "ACCESSORY" position. This insures that the driver would almost certainly have to be in the vehicle.

2

SPECIFICATION cont.

In the event that a door is opened while the ignition key is in the "ON" or "ACCESSORY" position, the RC timing circuit supplying Q3 and Q4 are shorted. If both front doors are not closed prior to returning the ignition key to the "OFF" position, the sy stem remains totally deactivated. It should be noted that in addition to the requirements of the NHTSA, this system also employs an "OFF/ON" switch which is easily accessible to the driver. This switch is not shown on the schematic, however, it supplie s ground to the system, and must be in the "ON" position prior to turning the ignition key from the "ON" or "ACCESSORY" position to "OFF" in order to activate the system. This switch allows the system to be turned off when it is not needed (cold weather ) or if the ignition key switch is not used to deactivate the system.

It is understood that component electrical ratings must be maintained as in any electrical device.

If you have any questions or require further information, please contact me.

Thank you for you time and promptness in reviewing this matter.

ENCLOSURE

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