Engine wiring Harness

[highspeeddirt]

I'm going to get a new engine harness for my challenger. (74) I've done a lot of searching the forum.  And I see alot of posts of folks bragging on year one harnesses. Has anyone used the ones Dave has at Roseville Moparts? Also, I read to get a 73 harness and not a 74 harness because of extra seat belt wiring?  Comparing the wiring diagrams, I don't see a difference.  I may be missing it, but if a 73 harness will work, it'll be chaeper too. On that note, the one listed on Daves site says 72/74?  Just trying to figure out my best way to go and save money too. And now to let my stupid show a little, what is this in the picture?

[74challenger03]

the 74 dash harness has 2 plugs for seat belt on driver side next to dash lights.If you dont have the seat belt relay box to plug in then the car wont start.found this out when i disconected mine.

[swede-cuda]

 :clueless:is there a pushbutton on top of the relay in the pic?..is it the emergency start relay,for when....something with the seatbelt stuff break down..??

[highspeeddirt]

:clueless:is there a pushbutton on top of the relay in the pic?..is it the emergency start relay,for when....something with the seatbelt stuff break down..??

I think I have pretty much came up with the seatbelt interlock bypass relay. The long stem sticking out has a push button in it. Can't say that I'm 100% but everything I'm reading points that way. I'm going to go ahead and get the YO harness that is for the after 10/12/73 build date. (which the guys at M&H told me was specifically for cars built with the seatbelt interlock?) I'll work on bypassing it afterwards. My harness is cut up and hard and brittle so I don't want to even mess with it.

[74challenger03]

that might be the relay for the dash/key light that gos out after 30 seconds,was it under dash?Will be working on my car do you want me to look?Are you doing the whole harness or only engine bay?Let me know i might want your old harness mines even worse then yours.

[highspeeddirt]

that might be the relay for the dash/key light that gos out after 30 seconds,was it under dash?Will be working on my car do you want me to look?Are you doing the whole harness or only engine bay?Let me know i might want your old harness mines even worse then yours.

No its still connected to my engine harness.   I'm just doing the engine harness right now.  Not going to mess with the dash harness unless I have issues.  Here are a couple more pics..... 

[74challenger03]

i know it is mounted on driver side fender before the starter relay.cant find it on classic car wiring diagram and my 73 manual doesnt have it.Its got to be a 74 only part.My car should be back home tomorrow so i can look to see what it feeds.

[highspeeddirt]

i know it is mounted on driver side fender before the starter relay.cant find it on classic car wiring diagram and my 73 manual doesnt have it.Its got to be a 74 only part.My car should be back home tomorrow so i can look to see what it feeds.

Found this picture of someones online showing it located right there above the drivers shock tower like you said.  I spoke again with M&H about their harness, and he told me it is a switch for the seatbelt interlock. It won't be going back on of course. 

[Jamiez]

You can install the seat belt interlock and just not hook the 2 wires up that go to the bottom of the seats (weight sensors).  That way you don't have to mess with modifying the harness.  The car will start/run just fine even with the belts unhooked. 

[highspeeddirt]

You can install the seat belt interlock and just not hook the 2 wires up that go to the bottom of the seats (weight sensors).  That way you don't have to mess with modifying the harness.  The car will start/run just fine even with the belts unhooked.

If I was to do that, know anyone who remanufactures the switch in the picture? Because mine looks like heII!

[swede-cuda]

  no..but will a nos do it for you.www.skevab.se

[swede-cuda]

  sorry,the relay is gone from skevabs site..

[Jamiez]

Based on my 74 part manual these are the part numbers:
3746724
3746910
3746916

Mine is a 3746910 based on the stamping:


There is one listed on eBay:
http://www.ebay.com/itm/NOS-MOPAR-1974-SEAT-BELT-INTERLOCK-OVERRIDE-SWITCH-PLYMOUTH-DODGE-CHRYSLER-/380414638986?_trksid=p4340.m185&_trkparms=algo%3DSIC.NPJS%26its%3DI%26itu%3DUA%26otn%3D5%26pmod%3D230678928547%26ps%3D63%26clkid%3D6864505396568174188#ht_500wt_1099

But that's probably more than you want to pay. Maybe someone has an interchange manual?

[highspeeddirt]

I appreciate it, but I most likely won't put it back on. I ordered the M&H harness from year one. The tech guy told me to give him a call back if I have any issues bypassing it.