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Discussion Starter #1
Okay, so I picked up this ’69 coupe, 350, 3 spd auto on the floor, HEI, and the wiring under the hood is a disaster. Different colored wires connected to other different color wires with crimp connectors or wire nuts. So I decide I need to rewire it. Being new to this I assumed an engine wire harness would take care of the engine so I bought an engine wiring harness made by American Autowire from Classic Industries. I assumed a headlamp harness was just the lights but as I look more at the product description it looks like it covers a lot of the under-hood electrical components so I’ve decided I need that one too.


Now here’s the train wreck. I’ve got a couple pics on Photobucket that help explain. Picture 1 is a close up of the engine harness plug. Notice all the cut wires. The light blue, darker blue, purple (?) and woven covered wire are the only four wires left. Picture 2 is a shot of a hole and a rubber plug in the firewall down and to the left of the engine harness base. There are two red and one blue wire coming through the big hole and a green, orange and black wire coming through the plug.


Sooo, my conclusion is that someone cut the wires coming from the harness base and just wired them directly from the inside through the openings in the firewall. So, logic tells me if I plug in my new wiring harness and connect things it won’t work because half the wires bypass this plug. So, it seems to me, that the only way to get this thing wired correctly is to also buy the dash harness and rewire inside so everything goes to and comes from where it is supposed to which will in turn let me plug in a new engine and headlamp wiring harness and wire everything up correctly using the diagrams in a Factory Assembly Manual. Correct?

I see different versions of assembly manuals or at least different covers when I look online, is one any better than another or are they the same? Also, any recommendations on wiring harnesses or is Classic and AAW pretty much the way to go?

Thanks.

http://s713.photobucket.com/albums/...140/withac_123/?action=view&current=1post.jpg


http://s713.photobucket.com/albums/ww140/withac_123/?action=view&current=2post.jpg
 

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Well we need to know did you buy a Factory Fit OEM line or the update line for modified vehicles harness from AAW. If it is Factory Fit then you must set everything up under the hood as factory so no HEI would be included on that harness and you will have to make modifications. If it is the classic update line you should have HEI capabilities built in to the harness. You also haven't told us if the charging system is stock 3 wire, external Voltage Regulator or was it also modified to use a 1 wire internal Alternator/Regulator?

Both sides of the connector are accounted for by your statement that you have engine and headlight harnesses. The two of them slide together and form the engine bay side of the Bulkhead Connector, as seen in your pictures. That being said everything should pass through the bulkhead connector to the fuse panel on the other side. Either harness option from AAW will do that for you albeit the classic update expects a new style fuse block using blade style fuses. Factory fit expects the OEM glass fuse block on the other side.
 

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Your "holes in firewall" photo only shows up as thumbnail, at least on my end. It's possible that those wires are something that the p/o added, such as gauge wiring rather than buggering up the dash harness. You need to trace those and see where they go. Dash harnesses are expensive, so make sure you really need one
 

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Discussion Starter #4
The new harness is not the full blown upgrade, just the standard OEM with the exception of being modified for the HEI.

Well we need to know did you buy a Factory Fit OEM line or the update line for modified vehicles harness from AAW. If it is Factory Fit then you must set everything up under the hood as factory so no HEI would be included on that harness and you will have to make modifications. If it is the classic update line you should have HEI capabilities built in to the harness. You also haven't told us if the charging system is stock 3 wire, external Voltage Regulator or was it also modified to use a 1 wire internal Alternator/Regulator?

Both sides of the connector are accounted for by your statement that you have engine and headlight. The two slide together and form the engine bay side of the Bulkhead Connector. in your pictures. That being said everything should pass through the bulkhead connector to the fuse panel on the other side. Either harness option from AAW will do that for you albeit the classic update expects a new style fuse block using blade style fuses. Factory fit expects the OEM glass fuse block on the other side.
 

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Discussion Starter #6
Thank you, yes, I forgot to mention, sorry folks, I'm new to this and still learning. It has an aftermarket tach and triple gauge set, looks like I need to trace down some wires before you guys can really help me. That being said, with only four wires coming out of the engine harness base wouldn't that still suggest I probably can't just plug in my new one?

Your "holes in firewall" photo only shows up as thumbnail, at least on my end. It's possible that those wires are something that the p/o added, such as gauge wiring rather than buggering up the dash harness. You need to trace those and see where they go. Dash harnesses are expensive, so make sure you really need one
 

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Well you can use the factory locations and tachometer wiring harness from AAW to send signal to the aftermarket Tach you already have if restoring to factory OEM gauges is not in your plan. The same can be done for Temp, and Volts using the AAW wiring. The Factory position for the Tach is already empty in the Bulkhead Connector and is easy to add at this point in your rewire project.
 

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Discussion Starter #9
So don't I need to return the wiring harness and get one wired for a tach and gauges do I, can't I just use the wiring harness I bought and leave the tach and guages wired like they are?

Well you can use the factory locations and tachometer wiring harness from AAW to send signal to the aftermarket Tach you already have if restoring to factory OEM gauges is not in your plan. The same can be done for Temp, and Volts using the AAW wiring. The Factory position for the Tach is already empty in the Bulkhead Connector and is easy to add at this point in your rewire project.
 

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Discussion Starter #10
Okay, I traced some wires. The big hole has a heavy gauge and lighter gauge red wire coming through it. Both go to the ignition switch so I figured they were important, probably should go through the plugs on the engine harness but have been cut, so I didn’t trace where they went under the hood. The blue wire coming through the big hole goes to a push button what was mounted in the dash that as far as I can tell does nothing. The end under the dash is quick spliced into a switched hot wire and the blue wire taps into a wire coming out of the voltage regulator that goes to the starter.

The orange wire coming through the rubber plug goes into a bundle of wires behind the dash and the other end goes to a plug high and left on the engine side of the firewall behind and under the passenger side hood hinge and spring assembly. The black wire coming through the plug goes to the aftermarket gauges, and the green one goes to the aftermarket tach.

So where it appears the two red wires and the orange one at least go directly to key components not aftermarket add ons and don’t go through any wiring block, I’m thinking if I want them to run through a new engine/headlamp harness I will need to replace the underdash harness so things hook up right when the engine/headlamp blocks are plugged in on the firewall. Correct? Either that or see if it is possible to patch these direct wires back into the system on the under dash side but then I’d have more weak spots from the splices, right? As much as I don’t want to drop the coin on an underdash harness, I wonder if it’s the only way to straighten out this whole mess. That would replace the wires going directly to end points under the hood with wires wired directly into the plug for the wire harness. Make sense?
 

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The orange wire going up under the passenger fender is going to the heater motor. It sounds like maybe previous owner had a MSD module and one of those red wires were maybe going to it.
 

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To answer your question on getting a different harness...no. If you intend to use the aftermarket gauges you already have you can use the idiot light wire and routing for the Temp gauge. If you are running voltmeter - Camaro's cane with Ampmeters that had their own wiring loop - you can run aux wiring from inside the pass compartment to use a volt meter.

So all you really need is the AAW tach feed harness. I say "need" only if you don't want to run your own signal wire to the bulkhead connector in position X then from X on the other side to the coil or tach lead of your HEI module.

If you do intend to replace aftermarket to factory then you buy two harnesses from AAW. The first being the extension harness to create the service port. The second being the correct console harness as they are different based on type of transmission your vehicle has. As for gauges both OER and Classic Head Quarters make reproductions of the saw tooth gauge packs. CHQ uses the original wiring configuration and external resistors on the temp and fuel gauges.

OER uses internal and at one time used different connectors on the harness then original. I have been told they have gone with the original connectors now but I use CHQ when I'm doing gauges.

On the other hand OER makes a very good Tachometer reproductions and top notch speedometer units. Order the correct Tachometer for the engine you have and you are good to go. All in all the conversion to factory gauges in a non gauge car is a weekend project and other then getting to the bulkhead connector (easy if the fender is removed) and cutting the back of the fuel pod out to fit the Tachometer it is easy skill work. There are templates here for the Tachometer cut out.
 

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Discussion Starter #13
Thanks. I'm thinking where the aftermarket tach and gauges are working I'll leave them alone for now. If I can replace all the wiring under the hood and have it still run I'll be happy. If I can do it without buying an underdash harness I'll be even happier but I'm not holding my breath.

To answer your question on getting a different harness...no. If you intend to use the aftermarket gauges you already have you can use the idiot light wire and routing for the Temp gauge. If you are running voltmeter - Camaro's cane with Ampmeters that had their own wiring loop - you can run aux wiring from inside the pass compartment to use a volt meter.

So all you really need is the AAW tach feed harness. I say "need" only if you don't want to run your own signal wire to the bulkhead connector in position X then from X on the other side to the coil or tach lead of your HEI module.

If you do intend to replace aftermarket to factory then you buy two harnesses from AAW. The first being the extension harness to create the service port. The second being the correct console harness as they are different based on type of transmission your vehicle has. As for gauges both OER and Classic Head Quarters make reproductions of the saw tooth gauge packs. CHQ uses the original wiring configuration and external resistors on the temp and fuel gauges.

OER uses internal and at one time used different connectors on the harness then original. I have been told they have gone with the original connectors now but I use CHQ when I'm doing gauges.

On the other hand OER makes a very good Tachometer reproductions and top notch speedometer units. Order the correct Tachometer for the engine you have and you are good to go. All in all the conversion to factory gauges in a non gauge car is a weekend project and other then getting to the bulkhead connector (easy if the fender is removed) and cutting the back of the fuel pod out to fit the Tachometer it is easy skill work. There are templates here for the Tachometer cut out.
 

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Good answers given. Yes, orange wire is blower motor power.
Blue wire to a push button switch is probably starter button added by a PO.

You're on the right track, identifying each wire and its function and go from there.
Of course, you're taking notes of all the wire functions you're finding - we can't remember forever.
 

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Discussion Starter #15
Thanks tons to all of you.

I think the gauges and tach that the PO's have put in will be good enough for now. Maybe some day I'll upgrade to stock but that's a long way off so I'll worry about it then. As for now, thanks for the help with the wiring. Maybe before I buy the underdash harness I'll take everything apart inside and see if I rewire it like it should be, going through the wire harnesses, but I'm not holding my breath. I don't want to drop that much on an underdash harness but I'm thinking it may be the only way to straighten things out and know for certain that things are wired like they should be.

Any other ideas or suggestions feel free to chime back in.
 

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Discussion Starter #16
I’m comparing the wires coming out of the old engine harness firewall block with the new engine harness I have by AAW. The wire placement and colors don’t come close to matching. I wonder if one of the PO’s wanted to rewire it and rather than find the right wiring block used one they found who knows where, which is why some wires are cut off and wired directly, bypassing the fuse block/firewall block, because maybe the connections didn’t line up. I would assume that if I now get the correct underdash harness, where my engine harness is now correct, even wired for my HEI, that I should be able to wire things up the way they are supposed to be and everything (crosses fingers) should run. Sound like logical explanation? I mean why else would the old wires not line up with the new correct harness?
 

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