Accessory Power - Team Camaro Tech
Electrical & Wiring Troubleshooting electrical.

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post #1 of 21 (permalink) Old Sep 16th, 18, 02:45 PM Thread Starter
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Kevin
 
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Accessory Power

Was wondering if a 69 camaro has accessory power on first click of key or turning key backwards.I have msd atomic efi and every time I try to find a bad ground or want to listen to the radio etc it has to be on ignition and it floods the engine. I have taken my test light but either the fuses are off or have constant power while the key is in those positions.If there is no wire that has power like that then would it be ok to disconnect the fuel pump ground or unplug the atomic? Any help would be greatly appreciated

Thanks,
Kevin
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post #2 of 21 (permalink) Old Sep 16th, 18, 03:42 PM
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Acc is to the back.

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post #3 of 21 (permalink) Old Sep 16th, 18, 05:34 PM
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Re: Accessory Power

Your 69 Fuse block (if that's actually what you have) should be very close to how it is in my 68 Chevy II Nova:




The top arrow one is a battery tap and is labeled BAT. This terminal has power all of the time regardless of key position.




The next arrow down is an accessory tap and is labeled ACC. This terminal will have power when the key is rotated back from the off position and when the key is in the forward Run position and dead at all other times (key off and in crank position).




The third arrow down is an ignition tap labeled IGN. This terminal will have power when the key is in the Run AND crank position and dead at all other key positions (key back towards accessory and when the key is off).




The last lower arrow terminal towards the left bottom of the fuse block is a lighting tap and is labeled LPS. This terminal will have variable voltage between 0-12V only when the parking and headlight switch is pulled out. The variable voltage occurs from how much the headlight knob is twisted one way or the other.





These 4 taps as I call them are for adding additional circuits to the car and if you notice, they are made to accept keyed plastic housings (or one can use standard fully insulated female connectors in any of them). The reason is they are keyed is so that the new addition cannot be plugged into the wrong tap.


Here is a factory cruise control lighting plug that will only fit into the LPS terminal:



and the tap location in the fuse block again:





And one for a rear defroster that will only plug into the ACC tap:



and the tap location in the fuse block again:




Not to tell you how to do things but I would wire up the fuel pump to the IGN terminal (and add a relay is needed) and then also wire the trigger wire for the MSD Atomic EFI also to the same IGN terminal (and again adding a relay if needed). Now wire your radio to the ACC terminal. Now if the key is rotated back the radio will work but not the fuel pump and EFI.

The taps as I call them are fused by the neighboring fuse in the fuse block and it's hard telling how much current you are pulling with the added items and how loaded the existing circuit is and this is why you may have to add relays to where the tap in the fuse block activates a relay and then the main power for the fuel pump and EFI is off of the battery but switch the proper way by the ignition switch.

Jim
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post #4 of 21 (permalink) Old Sep 16th, 18, 06:20 PM Thread Starter
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Re: Accessory Power

Wow thanks so much. Just got it and I would never have things like the radio set on ign for main power. Came wiith three amps and 2 subs and those are run off ign too instead of the radio power antenna lead for remote on. Car is fantastic other then wiring so might be getting a painless present under the tree for a winter project.
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post #5 of 21 (permalink) Old Sep 16th, 18, 06:38 PM
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Re: Accessory Power

Quote:
Originally Posted by NH427 View Post
Wow thanks so much. Just got it and I would never have things like the radio set on ign for main power. Came wiith three amps and 2 subs and those are run off ign too instead of the radio power antenna lead for remote on. Car is fantastic other then wiring so might be getting a painless present under the tree for a winter project.
You just have to investigate and see what can be salvaged and what could be done to make the existing wiring good once again. I've seen minimal damage before that with some work can be made good once again while other times it's best to get either a direct fit replacement or an upgraded universal one.

While a painless present may or may not be "painless" with the installation, there are other choices out there to look at.

Jim

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post #6 of 21 (permalink) Old Sep 16th, 18, 06:48 PM Thread Starter
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Re: Accessory Power

Jury still out if it can be saved. The front driver blinker was not working but running light was fine. The quick disconnect by the fender had no power and someone had removed some insulation and wrapped a black wire around that in what I can only assume was to give it blinker power at one time. On the steering column both sides the light blue has power and then it goes into the harness and have not idea where it goes from there so I ran a new wire for now to pass inspection. Regardless of complete replacement or not I will have a fun time working through the rats nest. Thanks again for the help.

Last edited by NH427; Sep 16th, 18 at 07:02 PM.
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post #7 of 21 (permalink) Old Sep 17th, 18, 09:29 AM Thread Starter
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Kevin
 
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Re: Accessory Power

Any chance you know the color of the wire for accessory off of that 25 wire or so steering wheel shaft harness?

Thanks
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post #8 of 21 (permalink) Old Sep 17th, 18, 04:18 PM Thread Starter
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Re: Accessory Power

So the radio and almost everything else was on accessory I was just not turning the key back enough. I had to wiggle the wheel to rotate it more. That being said the fuel pump is hooked up to that so I have to track it down and move it. On the fuses that donít light up under accessory they still barely light up my probe. Not sure if power can slightly bleed over or a bad ground but it seems every fuse has slight power under accessory?
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post #9 of 21 (permalink) Old Sep 17th, 18, 06:21 PM Thread Starter
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Re: Accessory Power

So I just tested with a multimeter and under accessory I am getting 7 volts on all connections and 13 on accessory connections and things like the horn which always are on. Any ideas?

Thanks
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post #10 of 21 (permalink) Old Sep 17th, 18, 07:16 PM
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Re: Accessory Power

What voltage is this "slight" amount of power ?. (I'm a slow typer and saw you answered this)

While I don't know what probe you have, maybe look at the below video and it might help. While it may not be connected directly to what issue you are having with showing slight power on things, it might help tracing down ground and/or power issues.


Power can "bleed" or backfeed and a good example is when the parking lights up front and/or the taillights in the back of the car do not ground well. These bulbs are normally an 1157 type of bulb with two filaments and one filament is for the brake light (the brighter of the two) while the other filament is for the parking lights (the dimmer of the two). Normally if the 1157 bulb is grounded well then when power is sent to it for something to activate the brighter portion (brakes applied or turn signals) the brighter of the two filaments will light up and then it goes to a ground. The problem is when there is no ground on these type of bulbs and now if the brakes are applied power gets sent to the brighter filament, then through backwards through the dimmer filament and then the remaining power eventually finds a ground and goofy things happen like the dash turn signals lighting up when the brakes are applied and things like that.

I would go over your grounds and you need a decent sized cable from the battery negative post to the engine block and then more connections from the engine to the firewall or from the battery negative post to the fender and/or the firewall. Looking at a ground connection normally will not reveal poor connections electrically. Mechanically they may be tight and solid but you need to concern yourself with making good electrical connections.

Jim

1974 Spirit Of America Nova (being restored), 1973 Nova Custom, 1968 Chevy II (Garage Find 2012)

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Last edited by SOA-Nova; Sep 17th, 18 at 07:20 PM. Reason: I'm slow with typing things out :)
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post #11 of 21 (permalink) Old Sep 18th, 18, 05:33 AM Thread Starter
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Re: Accessory Power

Thanks again for your help and I will look into ground issues. Besides the 7 volts I am seeing on ign which triggers the atomic efi and fuel pump everything works as it should. All dash lights behave like they should, all blinkers and brake lights work correctly etc. I am going to call MSD this morning but what are your thoughts on putting a toggle or push button switch on the ign switched power feed? The atomic has a large red wire that is direct battery and a smaller red wire that goes to 12v ign power. Would also be a slight anti theft device if you think that would work? I can't see many amps going through that wire since it is really just a remote on to I assume a relay inside the atomic. Also dumb question but how do you get tap connections as you called them above off the fuse panel? I tried to squeeze it, pull on it etc but no dice. They obviously lock themselves onto the terminal.

Thanks,
Kevin
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post #12 of 21 (permalink) Old Sep 19th, 18, 04:14 AM
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Re: Accessory Power

As stated, grounds, grounds, grounds!

I chased a "no rear lights" issue for a week. I could not figure out why my turn signals, brake lights, or parking lights did not work. With an volt/ohm meter, I had clean 12 volts on each required wire running to the bulb sockets. I then realized that I was grounding my meters black lead to the body. I removed one tail light assembly, and noticed (finally) that the bulbs were grounded to the taillight assembly, and that this assembly had "nipples" that were supposed to touch the body when the taillight assembly was bolted to the car body. Because they were removed when the car was painted, they did not ground themselves. Instead of removing paint, I built a ground strap for each taillight assembly, grounding them to a bolt in the trunk. Everything worked!

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post #13 of 21 (permalink) Old Sep 19th, 18, 07:39 AM Thread Starter
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Re: Accessory Power

Do you know if that device is off say the taillights can it affect things still? My plan is too take my meter and check for ground on all the ground wires I can fine. So far everything in the engine bay is showing me 12 volts when I touch the ground. Thanks guys for all of the help. If I ever figure it out I will be sure to post what it was.

Kevin
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post #14 of 21 (permalink) Old Sep 23rd, 18, 02:35 PM Thread Starter
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Re: Accessory Power

Ok so update on my issue. I added ground wires, stripped paint etc and still was having issues so I tried the remove one fuse at a time approach and lucky me the first fuse I went too was the issue. The fuse was for gauges 10 amp. When removed and I go too accessory I either have full voltage or none just like it should and my fuel pump no longer cycles in accessory which was the main problem. So what should the gauges fuse power because the only thing I have noticed is when in accessory I donít have a red gen light on the dash. Everything is working on my console gauges, dash blinker indicatorís, high beam, and all dash and console lights. Anyone know what that fuse should be powering up before all the 48 years of backyard mechanics played around?

Thanks
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post #15 of 21 (permalink) Old Sep 23rd, 18, 02:57 PM
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Re: Accessory Power

Do you still have fuel gauge, temp, and oil warning self-test lights when you turn the key to run? Brake might be on that as well but not sure without my wiring diagram.


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