[DeTomaso] Electro-techno question II: late 74 wiring and Moseley relay kit

[cengles at cox.net]

Dear Bill,

Thank you. Thank you. This is exactly the type of explanation and take-me-by-the-hand elementary electrical lesson that I need!!

You're a prince, Chuck Engles


---- SOBill at aol.com wrote:
>Chuck,
>
>Rick's headlight kit has nothing to do with the doors. It adds relays
>between the headlight switch and the headlights to reduce the current flowing thru
>the switch.
>
>
>The Headlamp door control is no doubt the most complex electrical circuit on
>the Pantera. I'll give a shot at explaining how the sequence operates.
>First the limit switches:
>The Doors Open Limit Switch contacts OPEN to stop the motor when the doors
>are fully open (i.e. the doors have reached the FULLY OPEN POSITION LIMIT).
>When the doors are not open ....... the doors are moving to the closed position
>or are in the closed position ..... the Doors Open Limit Switch contacts are
>closed.
>The Doors Closed Limit Switch contacts OPEN to stop the motor when the doors
>are fully closed (i.e. the doors have reached the FULLY CLOSED POSITION
>LIMIT). When the doors are not closed ..... moving to the open position or are in
>the open position ..... the Doors Closed Limit switch contacts are closed.
>Now the Headlamp Relay ...... which controls the doors but not the
>Headlamps
>The Headlamp Relay reverses the power polarity to the motor so the motor
>rotates to open or close the doors depending on the limit switch positions. With
>the Ignition Switch in an ON position: If the Headlamps are ON, the doors
>will open and remain opened: If the Headlamps are OFF, the doors will close and
>remain closed.
>Now, how does it all work:
>Assume the doors are closed, headlights are OFF, and the Ignition is in ACC
>or RUN. The headlamp relay shown in Headlamp and Headlamp Doors Page 1 of 2
>is deenergized. Power will be applied to the Yellow and Green wires at the
>limit switches. The limit switch condition shown in the top left most diagram on
>the Headlamp and Headlamp Doors Page 2 of 2. Since the doors are closed, the
>contacts of the Doors Closed Limit Switch .... the bottom switch of the two,
>.... the one with the two Brown and one Green wires attached ..... are
>open. No power will be applied to the motor. This is a stable state.
>Assume that now the headlamps are turned ON. Since the Doors Open Limit
>switch is closed .... because the doors are not open ..... a ground connection
>will be applied via the Gray wire, through the Doors Open Limit switch and the
>Yellow wire to the motor. +12V will be applied by a Brown wire attached to
>the Doors Closed Limit switch (but not dependent on the doors closed limit
>switch contacts) to the motor. The motor will turn and the doors will start to
>open. This is the situation shown in the middle-top diagram on page 2 of 2.
>This is not a stable state because the doors can not move indefinitely.
>Assume the doors have opened to the point where contacts of the Doors Open
>Limit switch have opened. Power to the motor has been interrupted and the
>doors stop moving in the open position. This is the situation shown in the right
>hand-top diagram on page 2 of 2. This is a stable state.
>Assume now the headlamps are turned OFF. The headlamp relay will deenergize
>and 12V power will be applied to the motor via a Yellow wire which is
>attached to the Doors Open Limit switch (but is not dependent on the Doors Open
>Limit Switch contacts) and a ground will be applied on a Green wire, thru the
>Doors Closed Limit switch then via a Brown wire to the motor. The motor will
>rotate and the doors will start to close. This is situation shown in the left
>hand-bottom diagram on page 2 of 2. This is not a stable state because the
>doors cannot move indefinitely.
>The doors move until the contacts of the Doors Closed Limit Switch have
>opened. Power to the motor will be interrupted and the motor will stop with the
>doors in the closed position. The system has now returned to the same
>condition as shown in the left hand-top diagram. This is a stable state.
>The cycle of doors opening, doors staying open, doors closing, doors staying
>closed has been completed.
>If the Ignition switch is turned OFF anytime during the door movement, the
>door movement will stop.
>If the ignition switch is turned OFF while the doors are open, the doors
>will remain open.
>Please let me know if this is understandable, or if it is too confusing. If
>you go through the above description with the electrical diagrams, you will
>see how it works. Then, considering the trouble symptoms, you will know what
>to test. Every signal you need is available at the limit switches.
>I have attached the two Headlamp and Headlamp Doors diagrams.
>Have fun,
>
>SOBill Taylor
>sobill at aol.com
>
>
>
>
>
>
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