[DeTomaso] Head Lights - How The Doors Work

[SOBill at aol.com]

Y'al,
 
I should have posted the message I sent Ed, so here it  is:
 
 
Ed,
 
 
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. 
The electrical  diagram is at: 
>>>>>http://www.panteraplace.com/Electrical/HEADLAMPS%20AND%20DOORS%20P1.pdf 
The Sequencing  diagram is at: 
>>>>>http://www.panteraplace.com/Electrical/HEADLAMPS%20AND%20DOORS%20P2.pdf 
If Fuse #10  (third from the bottom) is good (the AC/Heater Blower works), 
you will need to  do some trouble shooting. 
What all  the parts do and how it all works: 
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 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. 
The right  hand-bottom diagram on page 2 of 2 shows the relative position of 
the limit  switches on the driver side fender well and the wire positions on 
the switches.  Forward on the car is to the right.
 
Have fun,
 
SOBill Taylor
_sobill at aol.com_ (mailto:sobill at aol.com) 
 
If you are not having trouble with your headlamp doors at the  present time. 
you may want to save this message. Your day will  come.
 
SOBill
 
 
 




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