I'm slowly working out all of the electrical problems. My latest one involves the radio. I may need to mess around with the radio power and headlight power wires. It sounds like they may be reversed although at the radio I'm sure I hooked them up per my 74 Charger factory manual. The radio only works when the headlights are on. As soon as I turn the headlights off, the radio goes off even with the key left on. To me, this takes the longest time when doing a car; to straighten out all the electrical items. All is coming along though. I'm still trying to figure out the seatbelt interlock system and what all it affects. The front seat and seatbelts are currently out of the car. What can I do and not do due to the interlock? Can I start the car by pressing the red bypass button? Thanks for any insight into this interlock. Terry
Somewhere I have a diagram showing how to bypass that switch. I'll hunt it down and post here. If you choose to use this or not it's totally up to you.
OK, What I found was not what I recall so I did some circuit chasing in the shop manual. I have to admit I had some help. When I bought my Charger someone had already jumped the necessary connections with a paperclip. Yup, that's what I thought!! This first bit of information may work on some 1974 Chargers but mine was an early build and the wiring is different than discussed. My wire harness has no brown wire (only one black, one blue, and two yellow). I'll post it just for information only purpose just in case someone with that wire color scheme can use it.
This second insert is copied and pasted from the Official Shop Manual and matches my Charger exactly. On the left is the Interlock Start Switch. 12 volts comes in the lower right corner on wire S2 18Y (one of the two female spade connector shown in drawing CE 48 when ignition switch is place in the START position. Usually the Interlock Start Switch contacts are closed when the interlock control sees all the correct seatbelt inputs and passes that OK on to the Interlock Start Switch closing the contacts and allowing that 12 volts to exit the switch upper right on the second S2 18Y wire (second female spade connector shown in drawing CE 48) and on to the Start Relay. By cutting the two yellow wires and connecting them together all requirement for seatbelt use is bypassed. To test this procedure before actually cutting wires you might do as my Charger's previous owner did. Remember this is a modification so use it or not.
Last Edit: Dec 13, 2018 20:32:51 GMT -5 by goldrush
24 plus years USAF (Airborne Electronics) then another 25 years in consumer electronics. When I finally retired, I concentrated on a dream I've had for many years. Found a donor 1974 Charger SE Brougham with almost the identical options my new triple black had back in '74. Has taken over eight years but the transformation is nearly completed.
I think I posted at the same time you were editing LOL
Hey, at least we were on the same track. That first information came from something I had downloaded a while back.
24 plus years USAF (Airborne Electronics) then another 25 years in consumer electronics. When I finally retired, I concentrated on a dream I've had for many years. Found a donor 1974 Charger SE Brougham with almost the identical options my new triple black had back in '74. Has taken over eight years but the transformation is nearly completed.
Thanks for the replies. The video answers my questions. I've solved this set of radio electrical gremlins. I now realize I need to jumper out the interlock to start the car with the front seat and seatbelts out. Simple. Do most owners of 74s just bypass the interlock and forget about it but leave the interlock bypass switch mounted, seatbelts unplugged and control module under the dash in for original looks? Terry
Actually, I went one step further and designed/built a small circuit. Replaced the Interlock control circuit board using miniature relays to retain the seatbelt and key in buzzer feature but actually cut the two yellow wires and soldered them together inside the wire harness. Under the hood all appears original. I wear my seatbelt without fail but some people that will be riding with me don't. The buzzer and warning light are just little reminders...
24 plus years USAF (Airborne Electronics) then another 25 years in consumer electronics. When I finally retired, I concentrated on a dream I've had for many years. Found a donor 1974 Charger SE Brougham with almost the identical options my new triple black had back in '74. Has taken over eight years but the transformation is nearly completed.
You can get the orange canadian "interlock" module which in fact gets built in the jumper between yellow lines into the PCB. Canadian models boxes ( PN 3501371 and maybe some other with supersedes PN ) are just a warning buzzer control unit, because they were out of the federal starting interlocked regulations. With that box you can in fact remove the reset button from engine bay and the harness pigtail itself if wished ( no need for that thought ).
with this is a plug and play job.
these boxes floats on quite often on ebay.
Last Edit: Dec 14, 2018 9:27:32 GMT -5 by Nacho-RT74
with a Charger born in Chrysler assembly plant in Valencia, Venezuela