Interpretation ID: nht88-3.20

TYPE: INTERPRETATION-NHTSA

DATE: 08/26/88

FROM: ERIKA Z. JONES -- CHIEF COUNSEL NHTSA

TO: PAUL A. RENEAU

TITLE: NONE

ATTACHMT: LETTER UNDATED TO NHTSA FROM PAUL A. RENEAU, OCC - 1495

TEXT: Dear Mr. Reneau:

This is a response to your undated letter which this agency received in January 1988. I apologize for the delay in this response. In your letter, you presented a schematic and an engineering explanation of a power window system design and operation, an d asked whether the system meets Federal safety standard 118, Power-operated Window Systems (49 CFR @ 571.118). Based on my understanding of the information enclosed with your letter, it appears that your power window system would comply with Standard 1 18.

As I understand your system description, there are two electrical circuits that control power window operations. In the principal circuit, when the vehicle ignition key system is in the "ON" or "ACCESSORY" position, the power windows are operable. In m ost power-operated window systems, turning the ignition key to the "OFF" position means that the power windows no longer are operable.

However, in your system, a second, parallel circuit connects to the power window motor, and provides an energy source to allow an operator to close a power window when the ignition key is in the "OFF" position. The parallel energy source permits operati on only for a limited time period controlled by the electronic circuitry. My understanding is that with your design, the parallel circuit includes door switches which stop power window operation irrespective of the ignition key system position, whenever either vehicle front door is opened during the window closing sequence. According to your diagram and explanation, in such a circumstance, an operator must close the door, and return the ignition key to the "ON" or "ACCESSORY" position to reactivate th e power window system.

Paragraph S3 of Standard 118 specifies that power window systems may be closed only under certain listed conditions. One of those conditions is when the ignition key is in the "ON" or "ACCESSORY" position, as specified in S3(a). When the ignition key is in the "OFF" position, the power windows may be closed only under the conditions described in S3(b)

(by muscular force unassisted by a vehicle power source), S3(c) (upon activation of a key-locking system on the exterior of the vehicle), or S3(d). Paragraph S3(d) reads as follows:

During the interval between the time the locking device which controls the activation of the vehicle's engine is turned off and the opening of either of a two-door vehicle's doors or, in the case of a vehicle with more than two doors, the opening of e ither of its front doors.

Based on my understanding of the information you supplied, the only time the power windows in your system can be closed with the ignition key in the "OFF" position is during the interval between engine deactivation and opening of either of the vehicle's front doors. Standard 118 expressly permits this, so your system appears to comply with that standard.

I hope you find this information helpful. If you have further questions, please contact Joan F. Tilghman of my staff at this address or by telephone at (202) 366-2992.

Sincerely,