quote:Where is the connector block in referenced figure 18? Is it up behind the dash somewhere? It appears from my wiring diagram that the other side of the connector block may go to the ignition switch? Is this the case?
It is located above the steering column, and is connected to the ignition switch.
quote:The TSB is prescriptive but does not explain reason for the mod.
Correct, it does not. I'm not sure why this mod was done. Note that the circuit breaker that is call out (bottom of pg 13 of the TSB) is a "Non-Cycling" type. I don't think that there is a manual reset button on this breaker, which means that, once tripped, the breaker must be replaced. This may have been done as a deterrent to keep someone from replacing fuses (multiple times) before they looked for the source of the problem.???
quote:The configuration in my previous post is a fairly conventional motor reversing limit switch circuit that I have seen before. It doesn't do so well when a limit switch fails.
It is a simple double pole, double throw (DPDT) relay. Since the limit switches pass the full current of the door motor, if one limit switch fails in the open position position, then the doors won't function. If one limit switch fails in the closed position, then there will be big trouble in River City.
Referring to TSB Article No. 117, Fig. 19 (pg 14), it appears that one terminal of the relay coil is connected to the +12 via the circuit breaker, and that the other coil terminal (red wire at bottom left) is grounded via the headlight switch.
Referring to TSB Article No. 117, fig. 18 ('71 through early '74 cars), the black wire (bottom right) goes to ground, and the red wire (bottom right) receives power from the headlight switch (but only when the headlights are turned on).
I recently replaced a headlight door motor relay (for another Pantera owner) with a standard "off the shelf" relay and will do a write-up soon.
The Mike Drew relay mod is for the headlights only, and has nothing to do with the headlight door motor circuit.
John