1972 wiring questions

[boardog]

i am looking for some wiring info. car is a 72 charger, was originally a 318 auto with a/c. now has a 440 and a 4 speed with the updated sanden compressor and new lines. i have a wire in the engine bay that i can not identify. the car had no engine or trans when i got it. i have the body and electrical manual but the print is so small and blurred and i can't make out what the wire is. it's brown with a yellow stripe as shown in the pic. i would also like to know if someone has a wiring schematic for the dash cluster. it does not have a tach. once again the manual is of very little help even with a magnifying glass. one last question, i have installed electric fans and would like to know where to tap into a keyed on power source to run to the fan relay? thanks for any help.

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[Nacho-RT74]

The brown with yellow tracer wire is the ground to starter relay from tranny NSS which you wouldn’t use since changed to manual. You in fact need a different harness for the transmission. The ground to the relay will come out from clutch pedal.

What kind of electrical fan are your running? It gets some kind of control brain unit? Or they are simply turned on by a temp sensor? I have a diagram of my suggestion for wiring on that.

Note: ammeter cars should never get to source any kind of extra accesories from batt or starter relay post. This will overheat the bulkhead and will give you a wrong ammeter reading along with stress it too.

ALTERNATOR UPGRADE IS MANDATORY!

[Nacho-RT74]

this is a wiring diagram I made quite ago for a full setup options like an overrride switch ( with light or not )... also if you want to cut the power from ign switch OR the temp sensor cutting the power still with key in off... several noltes to reach your goals.

dual fan setup shown... can be single too.

the compressor clutch signal added relay will allow to turn on the secondar fan when A/C is on, no matter the engine temp and will get a higher cooling capacity on AC and prevent from engine overheat due the compressor drag.

the IGN1 signal IF WISHED can be taken from ballast blue wire. However as mentioned, if wired to the positive batt source into the same relay will allow to keep cooling the engine still after turn it off, just like modern cars.

[Nacho-RT74]

about temp sensors to drive the fans...

Here is a list I could get searching on the web, BUT DUNNO what options you got locally or if better... specs of switchs are ilustrated... Metric size and temp range in Celsious. This options were found from some Italy parts manufacturer website. BUT to get you the idea. Maybe some local parts vendor ( Napa, O'Reillys... ) could get you similar local options?. This is if the vendors on counter are techs and not just salesman behind a pc only providing parts by PN or Vehicle VIN.


All of these needs to be grounded somewhere around ( if decided to handle ground ) since they are chassis ground isolated. Then this ground will be sent to the relay to activate the fan according with the reached temp.

NOTE: I made this search and the previous diagram thinking on get a fully automatic cooling dual fan system according with the engine temp.

swingle fan can be used simply using a basic single stage temp switch, so just despite one of the fans relays and wiring shown on diagram. The optional A/C clucth relay and override switch can be despited too... allong with its light function if equipped.

[Nacho-RT74]

about dash cluster... is pretty much straight up... cluster is labeled on back which color of wire needs to get each point, but here is a section of  diagram

it's actually 73 but pretty much the same for 72... some small differences however not on cluster, but some places around

[Nacho-RT74]

AS MENTIONED. ALTERNATOR UPGRADE IS MANDATORY ON YOUR CASE.. Electric fans sucks A LOT of power... check the stickied thread about Charging and wiring upgrades I wrotte long time ago. Power must be spliced from the RIGHT SPOT. Alt stud if you plan still using the ammeter. Bulkhead won't allow to handle safely. Still feeding from batt, the bulkhead ( and ammeter ) will suffer this load to get the batt recharged by the alt. Thread explains why and how to keep it safe.


And... transmission harness. You can convert your existant one from auto to manual. Just need to cut the NSS plug on harness and get the reverse switch plug to match the transmission switch on transmission.

Brown wire with yellow trace will keep unused on this end since is the Ground to starter relay to safely start the engine in N or P, HOWEVER the wire can be rerouted to the pedal clutch switch.

AS far I recall the clutch pedal ground goes throught the firewall instead the bulkhead? can't recall. I'm not familiar with manual cars really

New Transmission harness for this can be found new repro around though and for the price...mmmmmm... IMHO it worths better get the full harness than just the plug.

Need to mention 72 and 73s (74s and lates got it too but they are different) got an specific neutral system to activate the seatbelt warning system relay. Dunno how is on manual cars. I don't have the diagrams for it.

[boardog]

thanks for the help. makes things a lot easier. i have a plug off the steering column i have a question on. its the 3 pin shown in the pic. i can't find anything on the dash harness that matches up.
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[Nacho-RT74]

The three wire plug from steering column is not used on A, B an E bodies cars. Those are actually used for Chryslers/Imperials to feed cornering lights. Sometime ago Mopar set this turning switch as a one piece replacement for all bodies althought on original years they were sold specifically for each model… switches with and without the cornerin light feed


With cornering lights…original one
 

Without:



Laters replacements began to use a spring loaded plain stud instead the rolller for the horn ring contact.

[AKcharger]