• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

Firewall hole location?

popslavaz

FBBO Gold Member
FBBO Gold Member
Local time
3:35 PM
Joined
Dec 23, 2016
Messages
700
Reaction score
512
Location
Channahon IL.
Getting all set to start the auto to 4 speed conversion on my '71 RR. Can some one please show or tell me where the hole in the firewall should be for the reverse light wire. Maybe someone could post a picture of it.
Thanks
POPS
 
I think it goes through the bulkhead connector. My car and factory shop manual are at my friends shop, so I don't have a reference here at home.
 
engine compartiment.jpg
Dodge, but I guess Plymoutn should be pretty much the same. It seems should be spliced from inside the cab at bulkhead ( check the diagram insert )

sorry, is the best pic I have
 
I have the wire diagrams for termination. J ust need to know where the wire gets from the trans. inside the cab to the dash reverse light.The reverse light has a grommet on it that requires a 1" hole.So what I need to know is the hole location on firewall?
Thanks for help
POPS
 
Most of the firewall layout in ’71 were the same as E-bodies, here is someone’s effort to document the hole locations on an E-body. There is normally dimples in all firewall locations where line workers added holes for various options.

3290890-firewall4.jpg
 
Not the best photo, I tried to circle what I think it is in yellow in the upper right of the photo. I was confusing the Tach and reverse light?

reverselight.jpg
 
that could be the clutch NSS signal for the starter relay.

Not being a smartA$$ but once again, I'm pretty sure the reverse light for the dash indicator was splitted from inside. There is not a reason to drill a hole on firewall and install a grommet for an extra signal splitted from outside going inside the cab which already exist into the cab. Just an opinion. Of course I can be wrong thought I'm not 4 speeds expert.

I know get a diff PN or assembly for an underdash harness just for the reverse light indicator is also not logic... but... well, dunno. Maybe easy to make an ad on at the moment!... whatever I'm thinking out loud
 
Last edited:
It’s well documented, at least in both ’71 &72 factory service manuals, that the 4-speed reverse indicator lead was grommeted through the firewall and connected to the transmission wiring on the engine side in those production years. I have never found any official factory diagrams showing exactly which dimples on the firewall were used for the specific grommeted pass-throughs. I know I’ve seen many examples years ago, fairly sure of the E-body diagram being correct for B-body for ’71 as well.
 
My bad and stand corrected!

74 thought. I guess pretty much the same on earliers.

IMG_6280.JPG
 
Thank You for your input.Makes sence it would be by the the bulkhead fitting since it plugs in to it by the wiper motor.
I think!!!!!!!!!! POPS
 
that could be the clutch NSS signal for the starter relay.

Not being a smartA$$ but once again, I'm pretty sure the reverse light for the dash indicator was splitted from inside. There is not a reason to drill a hole on firewall and install a grommet for an extra signal splitted from outside going inside the cab which already exist into the cab. Just an opinion. Of course I can be wrong thought I'm not 4 speeds expert.

I know get a diff PN or assembly for an underdash harness just for the reverse light indicator is also not logic... but... well, dunno. Maybe easy to make an ad on at the moment!... whatever I'm thinking out loud

There is no NSS on the older cars. The stock 69 uses a different relay where the NSS is soldered to the case grounding it all the time. When I converted from the 833 4 speed to the aftermarket 5 speed, I changed the start relay with one that would be used with an automatic and connected the new transmissions nss to the starter relay.
 
FOUND IT!!!!!!! Hiding in plain sight,there is a factory dimple just above where the gas feed bolts. That's where she goes.
POPS
 
Last edited:
Auto Transport Service
Back
Top