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Discussion Starter · #1 · (Edited)
Hey guys, I'm trying to figure out the wiring for what's going to be a home built PDU that will handle all the aux. lighting circuits. That PDU will be mounted under the hood and probably be in a Pelican or similar waterproof case. I know where there's a spot in the existing TIPM where I can tap into the ACC/RUN. So the thought process is Relay A only feeds power to the dash mounted rocker switches when the ignition is in either ACC or RUN. That will prevent any accidental battery drain. After some input from usmcdoc14 I may just power the rocker switches directly from the cigarette lighter once I start getting into the dash and do away with Relay A completely. The fuse panel is a Blue Sea Systems 5033 Block. Can you guys take a look and make sure I'm planning this right?

Link to PDF of diagram below:

Wiring Diagram v3



E-95

ETA: Sorry, I didn't think about the fact that PDF's often are carriers for malware and some might be reluctant to open one from a new guy. I added a JPG of the diagram. Harder to read but it's all there.
 

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Howdy E-95,

What you have drawn will work.

I ended up doing something similar. I agree with usmcdoc14 that relay is overkill. If you have the space that is fine but I would do away with it.

You can also combine relay 4 and B into one. You can drive a single relay with two inputs following the attached schematic. Where my diagram says "Tap into wire for dome lamps" you would tap into the wire for the backup lights.

I used the capacitor across terminals 86 & 85 to eliminate pulsing when the relay is triggered by the reverse lights. I did not know if I would get pulsing from the vehicle's can bus system when triggered by the reverse wire so I added the capacitor just in case.

This is how I did my backup lights. They come on with a switch or when in reverse.



If you don't want to mess with the bridge rectifier you can use a single 1/4" watt diode as shown in this diagram.


 

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Discussion Starter · #3 ·
Ah, thanks MoridinTX! Much appreciated! :beer:

I'll admit, I've never done any automotive wiring so this is all new to me. Looks like I need to pull out the books and learn about capacitors and diodes. :)

E-95
 

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Ah, thanks MoridinTX! Much appreciated! :beer:

I'll admit, I've never done any automotive wiring so this is all new to me. Looks like I need to pull out the books and learn about capacitors and diodes. :)

E-95
Welcome!

It was a learning experience for me as well. I wish I could take credit for it, but I learned from others.

The whole can-bus was news to me. I did not realize that the signal was pulse wave modulated (PWM) and that using that to drive the relay would cause the relay to pulse. I am just passing on others knowledge :)
 

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Discussion Starter · #5 ·
Yea, I read something along the way about the computer using PWM to verify onboard system health. Given the resounding advice to power the rocker switches directly off the ACC or cigarette lighter, will the PWM cause any problems? Or do those circuits not utilize PWM?

E-95
 

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Yea, I read something along the way about the computer using PWM to verify onboard system health. Given the resounding advice to power the rocker switches directly off the ACC or cigarette lighter, will the PWM cause any problems? Or do those circuits not utilize PWM?

E-95
The ACC is powered from the battery, not the can-bus. Running the switches from the ACC is fine. The only problem you would/may of have had is with your original design when using the relay triggered by the reverse lights.

The same goes with the design I posted when triggered by the reverse lights.
 

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Discussion Starter · #8 ·
The ACC is powered from the battery, not the can-bus. Running the switches from the ACC is fine. The only problem you would/may of have had is with your original design when using the relay triggered by the reverse lights.

The same goes with the design I posted when triggered by the reverse lights.
Outstanding! Yea, that design is getting altered per usmcdoc14's and your advice once I get some time. At this point I'm not in a huge rush since I can't seem to find any of the parts I need locally. I'm stopping by Graybar and the biggest local boat shop at some point this week.

And usmcdoc14, feel free to shoot me any of your Microsoft Paint designs and I'll be happy to spruce them right up in Visio for you. :D

E-95
 

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Discussion Starter · #10 ·
That's great! And they've got the Weather Pack connectors from Delphi Packard! :bounce:

E-95

ETA: When I order those, do I need to buy both the terminals and connector housings or do the terminals already come with the housings?
 

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That's great! And they've got the Weather Pack connectors from Delphi Packard! :bounce:

E-95

ETA: When I order those, do I need to buy both the terminals and connector housings or do the terminals already come with the housings?
I think they are separate..I would call. I usualy order a bunch of extra anyway when I screw them up.
 

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Discussion Starter · #12 ·
Good idea. I'll screw it up at least the first couple of times!

So my initial plan was to use the Weather Pack connectors for the bundle of wires going to the lights. That way if I need to do some upgrades, diagnostics, repairs, whatever . . . I can just quickly disconnect from the battery and that bundle and then pull the whole PDU to work on it in the house.

But this morning I started thinking, why not use a connector pair just off each light. If I decide to upgrade any lights or just flat out break a set it would be a simple matter of putting the connectors on the new lights and plugging them in. With your experience do you think this is a good idea? Am I over-engineering again?

E-95
 

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Yea, I read something along the way about the computer using PWM to verify onboard system health. Given the resounding advice to power the rocker switches directly off the ACC or cigarette lighter, will the PWM cause any problems? Or do those circuits not utilize PWM?

E-95
The PWM is used on the light circuits mainly to extend/maximize the life of the bulbs, secondary function of the PWM is for DRL. "System Health" check is done by current sensing devices inside TIPM which may employ PWM if current draw is incorrect to avoid frying the circuit . To disband a myth here, the TIPM (Totally Integrated Power Module) not the CANbus is controlling your lights. CANbus (Controller Area Network bus) is simply the communication line between the different Control Modules (TIPM, PCM, Dash,....) like the Ethernet is used to connect different computers.
 

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Guess I'll throw in my 2cents on the diagram.

I don't care for the relay controlling all of your rocker switches. For one thing it's a bit excessive, but most importantly is it is a "all or nothing" system. As someone that has had relays fail and have replaced relays..If that relay fails, you have no lights. If that fuse blows, you have no lights. I would prefer to knock one of those variables out and just power all the rockers with a simple fuse. The current through that circuit will be FAR from requiring any sort of relay.

You also do not need to ground the relay 85's to the battery, any local mounting bolt/ground distribution is more than suitable and easier.

The 7.5a fuse for two 55w lights is not sufficient. At 14v (running) they should pull about 7.8amps, at 12v (just key on) they will pull over 9amps. The 20a fuse for two 130w Spots is also not sufficient. At 12v (key on) they'll pull about 22amps. The 15a fuse for the 200w circuits are not sufficient either, at 12v they'll want to pull about 17amps.

Go through and reconsider your fuse ratings, you want 10-15% higher rated fuses than expected in the circuit. Also consider just running small bladed circuit breakers; if something hiccups and it pops, you'll have your lights back on in a couple of seconds. I would definitely do that for the main 50a fuse feeding the distribution block.


Not sure if I just don't know what I am talking about or everyone just glanced at the diagram...but that's what I noticed.
 

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Agree with the undersized fuses Goodysgotacuda. We are not talking here about current sensitive devices that need to be protected so fusing should be done in accordance to wire gauge and length of the wire used in the circuit since that is the biggest fire risk in such circuits. Clearly the wire gauge should be in accordance to the expected current draw and length of wire with some room to spare.
 

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Discussion Starter · #16 · (Edited)
Panamon Creel, thanks for putting that in terms this MCSE can understand! :)

Guess I'll throw in my 2cents on the diagram.

I don't care for the relay controlling all of your rocker switches. For one thing it's a bit excessive, but most importantly is it is a "all or nothing" system. As someone that has had relays fail and have replaced relays..If that relay fails, you have no lights. If that fuse blows, you have no lights. I would prefer to knock one of those variables out and just power all the rockers with a simple fuse. The current through that circuit will be FAR from requiring any sort of relay.

You also do not need to ground the relay 85's to the battery, any local mounting bolt/ground distribution is more than suitable and easier.

The 7.5a fuse for two 55w lights is not sufficient. At 14v (running) they should pull about 7.8amps, at 12v (just key on) they will pull over 9amps. The 20a fuse for two 130w Spots is also not sufficient. At 12v (key on) they'll pull about 22amps. The 15a fuse for the 200w circuits are not sufficient either, at 12v they'll want to pull about 17amps.

Go through and reconsider your fuse ratings, you want 10-15% higher rated fuses than expected in the circuit. Also consider just running small bladed circuit breakers; if something hiccups and it pops, you'll have your lights back on in a couple of seconds. I would definitely do that for the main 50a fuse feeding the distribution block.


Not sure if I just don't know what I am talking about or everyone just glanced at the diagram...but that's what I noticed.
I guess I should have prefaced my original post with, "I've avoided automotive electrical work like the plague prior to this so everything I'm drawing up here is based on what I've learned in the past couple weeks." :D

With that in mind, I've already eliminated that rocker switch relay from the plan based on usmcdoc14's and MoridinTX's advice. The rockers will be powered directly off either a TIPM tap or a tap in the cigarette lighter with an in-line fuse.

The 85's are grounded to the battery because everything will be inside a sealed case. Grounding to the battery just seemed easier since the PDU will be mounted right next to the battery and it will keep all the ground wires within the waterproof case.

Going back to my first paragraph (I'm a knuckle dragging moron when it comes to electrical) I guess I've had the wrong idea on fusing the circuits. I thought I was supposed to fuse the wire to less than its maximum amperage. So what you're saying is that I should fuse the 110W circuit with a 10A or 15A, the 200W with a 20A, and the 260W with a 25A?

And thanks to both of you for taking a look. :beer:

E-95

ETA: Oh, and I'm planning to use (again, on usmcdoc14's advice) 12ga from the PDU out to the lights and 10ga inside the PDU.
 

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....
ETA: Oh, and I'm planning to use (again, on usmcdoc14's advice) 12ga from the PDU out to the lights and 10ga inside the PDU.
12AWG wire if you are at 10' wire length (ground and positive wire combined length) could be fused at up to 30A max.
The 10AWG bus wire will likely be short from the installation point you've described (less than 3' combined?) so it could carry up to 150 Amps therefore you should be good
 
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