Would the following info work for a 1971 A/C Idiot light Dash harness to what i believe to be a 1972 forward/engine harness? And could i make the changes at the engine compartment side wiring harness bulkhead connector, or does it have to be done on the fuseblock side? The Dash harness is absolutely MINT and would rather not booger that side up if i don't have to....I have posted my engine side connector info at the bottom here; hopefully someone can confirm i'm working with a 72 harness in the engine compartment...(Pretty sure i am....if it was 71 i would imagine things would work....) This wiring is all in a 70 by the way.....(and i know i have to deal with some lamp re-wiring; not a problem there) I know the power wire has no connecton on the FB side Visibly..Just trying to double check before i dive in.


(Quoted from earlier forum post)

Below are direction to put a '72 dash in a ''70/'71 car. You're trying to do the opposite but this should help:

The changes you need to make are to the dash harness. FYI The 72 dash harness has the key warning buzzer and TCS relay. 70 has them under the hood, key warning is the horn relay and TCS is in the engine harness. Also the 72 dash harness will likey have a seat belt warning light and buzzer, not used in 70.
If you look closely at the wire side of the dash harness bulkhead connector (separate the fuse block from the bulkhead connector) You should see letters marking the rows and columns. The rows are A,B,C and D. The columns are S,T,U and V for the forward lamp harness and W,X,Y and Z for the engine harness. The following instructions will refer to these coordinates.
Includes wire color, engine side connection and dash side connection

FORWARD LAMP HARNESS BULK HEAD CONNECTOR
AS – No wire (Should be black wire for key warning buzzer. Your warning buzzer will be under dash,)
BS – Dark Green – temp sensor – Move from CZ
CS –No change (Light Blue –LH dir signal)
DS –Black – J-block /amp gauge –Move from DX
AT –No change (Black grounds at horn button for horn relay)
BT –No wire
CT –No change (Dark Blue –RH dir signal)
DT –Black/dark Blue/White (looks like Black/White) –horn relay / amp gauge –Move from CX.
AU –No change (Light Green -head light high beams)
BU –No change (Brown –running/marker lights)
CU –Brown/White –voltage regulator / ignition switch (The brown white wire from the ignition switch is a resistor wire, supplies power to the voltage regulator when key is on) –Move from BT.
DU –Tan –brake dist block / brake warning light –Move from BS
AV –No change (Tan –head light low beams)
DV –Red –Main power feed to dash –Move from DW
ENGINE HARNESS BULKHEAD CONNECTOR
AW –Purple –starter solenoid S terminal / Neutral safety switch –Move from AZ
DW –No wire
AX –No wire (would be TCS)
BX –No change (Pink to ignition switch / engine side has white/orange /purple to coil)
CX –No wire
DX –No wire
AY –No Change (brown –coil / tach) Engine side wire to be added. SEE NOTE1
BY –No Change (dark blue oil pressure switch / oil warning light)
CY –Yellow –power to wiper motor / wiper fuse –Move from DS
DY –Light Blue –wiper motor (washer pump) / wiper switch –Move from DT
AZ –No wire
BZ –No change (orange blower motor / blower switch) Used on heat only cars, not used on A/C cars.
CZ –Dark Blue –wiper motor / wiper switch –Move from CU
DZ –Black –wiper motor / wiper switch –Move from DU
Note1: The wire in AY is found in a gauge dash harness only it is for the tach to coil. For a 70/71 harness this wire is not routed through the bulkhead connector. It is routed through a hole in the firewall.
Wires in DS and DT are for the AMP gauge, also gauge harness only wires. You will need to add these wires from the cluster connector to the connections under the hood.
NOTE: The 70 dash harness has the tach wire seperate from the bulkhead connector. Your 72 will have the tach wire in the bulkhead connector. You fwill need to add a wire from the bulkhead connector, engine side, to the coil - terminal or the TACH terminal if using GM HEI Dist.
(End Quote)

My Bulkhead connector is as follows on the engine side:
AS=No Wire
AT=Black
AU=Lt. Green
AV=Lt.Brown or Tan
AW=Black
AX=two Lt. Brown or Tans
AY=No Wire
AZ=Purple (Heavy, 10 Gauge?)
BS=Lt. Brown or Tan
BT=Dk. Brown
BU=Dk. Brown
BV=N/A
BW=N/A
BX= Pink
BY= Dk. Blue
BZ= Orange
CS= Lt. Blue
CT= Dk. Blue
CU= Dk. Blue
CV= N/A
CW= N/A
CX= No Wire
CY= No Wire
CZ= Green
DS= Black w/Yellow Stripe
DT= Lt. Blue
DU= Black
DV= No Wire
DW= Black (Heavy Gauge # 10? I believe it should be the Red Feed; Comes from Horn Relay)
DX= No Wire
DY= No Wire
DZ= Blue

Thanks for reading any and all input that you guys can give me before i burn my car to the ground.....lol. Please chime in on whether or not the chart above seems applicable to my situation.....Any advice appreciated!

Jack

I dunno about specifics of wire mappings and such... but it IS relatively easy to remove wires from either side of the bulkhead connector. The fuseblock side is probably easier as there is no sealant gunking up the works.

If the terminal is a male/spade terminal: gently squeeze the edges of the spade inside the connector from the plug in end. This will bend the terminal in slightly and release the lock tab on one edge so the terminal can be pulled out the back side. Use a screw driver to re-expand the terminal before insertion to make sure it locks again. Should also take advantage of it being out to clean the terminal faces.

If the terminal is a female/socket: there will be a small notch on one side of the terminal slot when looking at from the front plug in side. You need to make a bladed tool to fit up that notch and press the locking tang down towards the terminal. When the wire slips out the back of the connector body you know you have gotten it.

Do watch for the mirror image problem on these connectors. Things look backwards one way versus the other.

I dunno about specifics of wire mappings and such... but it IS relatively easy to remove wires from either side of the bulkhead connector. The fuseblock side is probably easier as there is no sealant gunking up the works.

If the terminal is a male/spade terminal: gently squeeze the edges of the spade inside the connector from the plug in end. This will bend the terminal in slightly and release the lock tab on one edge so the terminal can be pulled out the back side. Use a screw driver to re-expand the terminal before insertion to make sure it locks again. Should also take advantage of it being out to clean the terminal faces.

If the terminal is a female/socket: there will be a small notch on one side of the terminal slot when looking at from the front plug in side. You need to make a bladed tool to fit up that notch and press the locking tang down towards the terminal. When the wire slips out the back of the connector body you know you have gotten it.

Do watch for the mirror image problem on these connectors. Things look backwards one way versus the other.


Vrooom, thanks for the reply! It's the mirror image problem i'm definitely hiding from....lol. I'm just hoping for a "Yes you absolutely can" LOL. The mapping ALMOST seems exact, i'm pretty sure it will work, just looking to see if anyone has done the exact same....Thank you again for the info; much appreciated!

Yes you are working with 72 engine and forward lamp harnesses. You can repin them to work with the 71 . I'm assuming you will use the 72 horn relay and locate it on the driver side firewall.

In addition to what Steve stated about the sealing gunk on the engine side of the bulkhead. Because of the lengths of wires, some will be stretched and others have extra slack. I think you will have a neater installation if you moved wires on the dash side.

A couple of minor issues, because of the differences between 71 and 72, the key minder and TCS circuits will not function.

Yes you are working with 72 engine and forward lamp harnesses. You can repin them to work with the 71 . I'm assuming you will use the 72 horn relay and locate it on the driver side firewall.

In addition to what Steve stated about the sealing gunk on the engine side of the bulkhead. Because of the lengths of wires, some will be stretched and others have extra slack. I think you will have a neater installation if you moved wires on the dash side.

A couple of minor issues, because of the differences between 71 and 72, the key minder and TCS circuits will not function.

Elree, Thank you very much for the confirmation! How much more of a PITA will it be to do it from the fuseblock side? (Looks hard to get behind the fuses, does the fuseblock half separate? Sorry for the stupid question, just not sure....) The only reason i was considering doing it from the outside is b/c the dash harness is in unbelievable condition and the engine/forward is going to have to be operated on anyhow due to the obvious 2-4 lamp difference.

Actually the 2-4 lamp difference could not be a big deal as the 4-lamp outers are equivalent to the 2-lamp connections. Thus you could just leave the 4-lamp inners disconnected and all would work. The next owner might really scratch his head and wonder WTF but no harm done ;)

There are 2 screws that hold the inner bulkhead connecter and fuseblock to the firewall. With those removed there are a couple of plastic clips that lock the fuseblock to the bulkhead connector. So they come apart fairly easily. Depending on how much you have taken apart, it can be a good idea to just pull the dash harness completely out. Much easier to work on that way. Not to mention that this is the one area that seems to get hacked up the most over the years. So it could probably use a good going over.

Actually the 2-4 lamp difference could not be a big deal as the 4-lamp outers are equivalent to the 2-lamp connections. Thus you could just leave the 4-lamp inners disconnected and all would work. The next owner might really scratch his head and wonder WTF but no harm done ;)

There are 2 screws that hold the inner bulkhead connecter and fuseblock to the firewall. With those removed there are a couple of plastic clips that lock the fuseblock to the bulkhead connector. So they come apart fairly easily. Depending on how much you have taken apart, it can be a good idea to just pull the dash harness completely out. Much easier to work on that way. Not to mention that this is the one area that seems to get hacked up the most over the years. So it could probably use a good going over.

LOL.....i just got done putting the harness, dash, and heaterbox, cluster, etc....in. Nah, the dash harness is in BRAND NEW condition. Got it off of e-bay, and really could not believe not one cut wire, and clean as h*ll! I'll assume the backbreaking position if i do it from the inside unfortunately!