Radio connector on dash harness (2nd gen)

[BananaDan]

Question for the electrical gurus out there.  I have two items (vacuum pump for brakes, and aftermarket stereo) I need to hook up to switched power when the key is in ACC or ON.  I won't have the stock radio hooked up, so I pulled the red/white wire out of its plastic connector housing.  I put a female spade connector on the wire that runs through my firewall to my vacuum pump (power lead) and connected it directly to the red/white lead on the dash harness for the radio.  



Here are the questions:
I know the red wire is the switched power lead for the radio, but what is that white wire for?  My wiring diagrams say it runs to bulkhead connection D, which then goes to my Reverse/Neutral safety switch on my 727 trans?  Why would the radio connection have a wire that runs there?

Is this the right way or a safe way to hook up the power for my vacuum pump?  It was spliced into a wire under my dash previously but I didn't install it and I didn't take a picture before I removed my dash harness.

How do you recommend I connect the power for my aftermarket stereo?  Is it safe for me to run a wire directly from my new stereo to the fuse box and plug into the same spot the radio lead comes off of?

Is it safe for me to run both the vacuum pump and the new stereo off of the same circuit like this?

Dan

[BananaDan]

Nacho,  you out there?  I could use your insight.  Can the radio circuit be used for an aftermarket radio and my vacuum pump?  My stock radio will not be hooked up.

[Nacho-RT74]

1... the wire running to reverse light is hooked there just using that source like a splice to feed the NSS for the reverse function when key is in RUN. Will be the same than splice it directly to the fuse box, but on this way saving some wire feet. ( 2nd gens doesn't have enough sources to splice powers safe like 3rd gens do ). Obviouslly that means radio and reverse lighs share same fuse.

2... modern radios sucks less power than stock units, so THATS not a problem, and in fact is a gain.

3... how much load requires the vacuum pump ? Does the instruction sheet say that ? As far I rmember fuse what feed the Radio/reverse light is 20 amps, maybe less

[BananaDan]

I found a forum post somewhere that says it has 8 amps stamped on the model # sticker.  It is the 12VVCP pump by Classic Performance.

http://www.classicperform.com/Store/Heating_Cooling/12VVCP.htm

Dan

[Nacho-RT74]

check the fuse size... 20 amps should be fine if the wiring just feeds teh Radio, Back up lamps and the pump... if there is more on the same net, maybe you could upgrade the fuse to 25 amps.

You could use the Blue wire on engine harness though... will feed just in RUN. Radio is being feeded also on ACC and will suck power when you don't need the vacuum pump if you put teh key in ACC just for radio

[BananaDan]

Thanks, it is a 20a fuse.  Is it safe to go with a bigger fuse and not risk melting the wires?  Is there some room to play in there?  I know wire gauge dictates the amount of amps a wire can handle.  I'll take a look at that blue wire idea, that's not a bad idea since the pump is under my hood, then I don't have this extra wire passing through my firewall to get into my dash area for no reason.  One question though, is that blue line protected by a fuse, or should I put an in-line fuse between the blue wire and the pump for protection?  On my previous harness my pump was spliced into the red ignition line under my dash with an in-line 20a fuse.  My mechanic did the install and I didn't care b/c I knew the harness's days were numbered.  But now I would like to reinstall without cutting/splicing/tapping into my harnesses if at all possible.

[EDIT]  I just checked and I don't see any blue wires on the engine.  http://1970chargerregistry.com/Misc/Wiring_Diagrams.html  I see blue wires for the wiper motor, ac compressor (which I don't have), between the alternator and the ballast resistor, the tach and the fuel gauge.  [/EDIT]

Dan

[Nacho-RT74]

blue wire under the hood feeds the ballast and regulator ( also ECU and alt brush on electronic stuff cars )

3rd gens have a fuse on blue line JUST for some specific items inside like some cluster functions feeded from same line, but engine side of the blue line is not. I think 2rd gens not even that. You can splice an in line fuse to the pump though.

maybe even would use a relay to not overcharge the line what feeds the ignition and charge.

although use the radio source is not bad, I think its a better idea definitelly keep the sources inside the engine bay for the engine bay stuff

[BananaDan]

Thanks Nacho.  I'll leave it as it is for now, and if I start blowing fuses I'll relocate it to draw from the engine bay blue wire.

[twodko]

FWIW, I spliced into the radio's switched power lead (shown in your pix) for my SST........no worries.

[BananaDan]

blue wire under the hood feeds the ballast and regulator ( also ECU and alt brush on electronic stuff cars )

3rd gens have a fuse on blue line JUST for some specific items inside like some cluster functions feeded from same line, but engine side of the blue line is not. I think 2rd gens not even that. You can splice an in line fuse to the pump though.

maybe even would use a relay to not overcharge the line what feeds the ignition and charge.

although use the radio source is not bad, I think its a better idea definitelly keep the sources inside the engine bay for the engine bay stuff

Thanks twodko, that's what I want to do with my radio, now just to relocate my pump.

Nacho,
Are any of the blue wires you mentioned better than another to use for providing power to my pump?  These blue wires are hot when in accessory mode, right?  Currently, my pump turns on with the key in first position (ACC), prior to engine start.  Rather than splice (because I want to eventually lose the pump), could I make a pigtail on the ballast resistor with one female spade connector going onto the resistor providing two legs with male spade connectors?  One for the blue wire that would normally go onto the resistor, and the other for the pump?  This way I can undo this mod when I'm able to lose the pump and not have a splice in my new harnesses.

Thoughts?

Dan

[Nacho-RT74]

thats why I told you about use the blue wire, they are not hot on ACC like Radio it is.

yes you can, easier to use one of those double kind terminals to splice from ballast prong itself, and easy to get it back to stock.




or attach directly to the pump wire one of those terminals used on back of fuse box which gets a male leg to another terminal instead use the "splitter" pictured above... I couldn't find a pic of the one I'm talking about

[Nacho-RT74]

this one:



will make a smaller conection assembly at ballast prong and also one point less able to be loosen

[BananaDan]

Ok, so the blue wire on the ballast is what I'll use, with one of those adapters.  Thanks Nacho.  One thing, to make sure I'm clear, the blue wire isn't hot on ACC but it is hot in RUN after the engine is started I assume?  That should be good for the vacuum pump.  Even though mine ran on ACC before, I don't see why it would have to.  Right?

Dan

[Nacho-RT74]

yes, Blue wire just in RUN, not in ACC... thats why I suggested that source

[BananaDan]

Thanks Nacho, again!  I'll report back after I'm done.  Oh, what size fuse would you recommend?  I think the old splice job had a 15A fuse in-line, but the pump seems to be rated for a 6A-8A draw.  Does it matter?

[Nacho-RT74]

you could use a relay too.

if rated 6-8 amps, and not more sources, I would use a 10 amps fuse

[BananaDan]

Sorry, one more question.  Does it matter which side of the ballast resistor I use?

[Nacho-RT74]

the important is the wire, blue coming from ign switch. Ballast works the same no matter which one hooks on which side if brown or blue, but the power to the pump must be taken from where you hook the blue wire

( 4 prongs resistors are key coded but just to be sure primary and secondary resistances are correctly hooked, but singes are easier )

[BananaDan]

I re-did the wiring for my pump tonight Nacho.  How does it look?  I couldn't find the silver terminal you pictured, but I found the brass colored ones.  I would have preferred the other ones and maybe I'll mail order some, but I went to three auto parts stores and called two others and no one has them.

New in-line fuse for the vacuum pump.  It's ok that I put the fuse on the pump side of the wire run, right?  The way my mechanic did the previous install (when he tapped it into my dash harness red ignition wire), he put the in-line fuse on the dash splice side of the power run.  I figured I'd rather put it somewhere easier to get to for easier fuse changes if need be.


I plugged it into the right side as you can see, which has a blue and brown wire going into it.  The left side has a dark blue wire with a tracer and a light blue with a tracer going to it.

[Nacho-RT74]

not the brown side...

brown is the side going to coil, and gets power THROUGH ballast ( power decreased ) when in RUN. Use the other harness plug

NOTE...

if your car its a 70, it should be electronic voltage regulator and dual field alternator... cars with this setup are with the brown side being BOTH brown. Are you sure you got the right year engine harness ?

reason to be both brown since 70:

on earliers with single field alts, there is not a blue wire going to front of harness more than the one to + lead of coil ( coming from ballast ). When the charging system become on dual field alt/electronic regulator ( 1970 ) as standart equipment, the second field is feeded by a blue wire, then the coil + lead become on brown, so 70 and lates cars should get both wires BROWN on ballast splice. Thats I never talked to you about this detail. You are wiring a 70, right ?

...

The fuse can be there, not a problem. On that location you are just limiting the area of protection to JUST the pump. If you locate closer to the source splice, you are widening the protection to the pump AND to the wire, in case of a short on wire. Actually there is not a problem. We are talking about a new wire with nice soft isolation, it looks not close to heat sources able to melt the wire cover!

If thats was a problem we would get a fuse on EVERY wire of the car LOL, and actually not even the blue main source on engine got a fuse from factory LOL

[Nacho-RT74]

Forgett it I just checked a 70 diagram, and it looks brown wire change to coil was actually on 71s. Sorry!!!

anyway, the deal is, splice the power on plug with BOTH blue wires. This is the RUN source direct from key. The bown wire splice is full 12 volts just on START, then on RUN power is got through ballast

[BananaDan]

Ok, so move it to the left side with the two blue wires with tracers?  Easy enough.  To answer your above questions,  yes this is a 70 Charger, 440-4, auto trans.  It does have the Orange box EI system upgraded prior to me.  I replaced my engine harness last year with one from Bill Evans.  My wiring diagrams are not of total help to me since the car originally came with points, so they don't show the EI wiring.

Maybe I can bench test the ballast connectors with the pump disconnected after I start her up to be sure?  I have a voltmeter, but I'm not an expert.  Would I just touch the black on the VM to a ground, and touch the red to each ballast male prong while she's running and verify which one is delivering 12V?  How much voltage would the wrong side of the ballast be delivering?

Dan

[Nacho-RT74]

don't worry about the ballast side, either side works the same on ballast. You can in fact turn around the wires to ballast rpongs and will work the same, THE DIFF IS MADE by the wire hooked up as main source to feed the pump. You ned 12 volts on RUN and that is given by the double blue wire ( yes, traced )

[BananaDan]

Ok, now I'm confused.  I thought your posts above said I should move it from the side I'm on now (blue and brown wires) to the side with two blue wires, each with tracers?  Should I leave it as-is, or move it?  Is my voltmeter test idea correct?

[Nacho-RT74]

ok... step by step LOL

switch around the harness plugs from side to side on ballast, keep the splitter terminal and pump wire where it is right now, and you are SET, LOL

that will make the pump, getting full 12 volts in run from the right WIRE



Then... trying to explain it better

the side of ballast doesn't matter, the wire where is sourced is the important . the BALLAST itself works the same in any direction, but the stuff you hook up to their wires not

SORRY, sometimes is hard to me explain stuff in english