Can anybody help me with this wiring diagram?

I posted it in tech chat earlier but no help. Right now I have the two bigger leads from shunt running in picture below of my under hood “red” to the blue sea fuse block negative and black running to one of my negative battery posts.. I have a smaller 12 gauge wire running to just a negative terminal of the fuse block and finally I have another 12 gauge running to a 2 amp switched terminal on the blue sea fuse block... the ammeter led is on and it’s picking up some current but I know it’s not picking up anywhere near as much as it have in the truck with several leds and switches plus a 1300 watt audio system.. its showing a discharge when I trickle charge it with noco genius 5 at -0.9 which I believe but it’s only showing 2.4 amps total with everything in truck cranked up and turned on included ignition.. do I need to run more jumper wires to each negative lead on fuse block or one to the actual alternator? I’ve popped a couple of my main fuses already trying this... I’m not gonna keep testing my luck though.. the shunt I would’ve thought needed more positive leads to show load... I’m stumped and nothing is malfunctioning at the moment just not picking much current up for what I bought it for.. does anybody have experience with these? I’ve never wired a shunt but it seems simple and I’m just making it tougher than it is.. thanks for any help guys

 

Here’s a picture of it working but this is ignition on with no aux lights being used and radio is playing

 

Do you have a schematic of how its wired up? Its hard to get a mental picture going.

 

Your amp meter will only measure what’s running through the shunt. If you want it to measure total truck current, remove your neg and put on the load side of the shunt. Then run a 1/0 wire from the line side of the shunt to the battery neg.

You didn’t post a wiring diagram of how you wired your setup, so it’s hard to tell you exactly whats your issue is.

Most likely your amp is grounded to your frame.. etc and your frame is grounded directly to your battery via the factory strap. This would bypass the shunt and you wouldn’t see the current.

 

I’ve got both big shunt posts with 4 gauge marine wire one running to the negative battery post and one running to the main negative of blue sea fuse block. This is the blue sea fuse block that I’m referring to and using I’ve got the AB from ammeter running into the smaller posts on the front of the shunt.. then I’ve got the + from ammeter going into the 2 amp terminal on the switched side of the blue sea fuse block and the - from ammeter going into one of the ground terminals on the blue sea fuse block

 

I will try my best to draw something up real quick and post

 

@0xDEADBEEF Here is a drawing of how I’ve got it set up currently. Sorry I’m a terrible artist

 

Where is your 1300 watt amp neg and positive connected?

 

Second drawing attempt for better understanding possibly

 

Take a look at the wiring diagram you posted with the boat motor cranking amps example. You see the neg buss is connected to the battery via the shunt, anything connected to that buss bar it will measure the current of.
Now remove the boat motors neg wire from the buss bar and and connect it directly to the battery. You will then no longer be measuring the cranking current.
Another example would be if you connected the boat motor neg to both the buss bar and battery neg terminal; assuming they have the same resistance the amp meter would only see half the current.

 

Under passenger seat of truck but all of my grounds are connected to the battery throughout that I ran on my own with 1/0 oversized wire

 

So your amp is connected directly to the battery terminal? If that’s the case your bypassing the shunt, causing it to not be able to measure the current.

Btw, your drawing shows going from the battery to the B side of the shunt and the A side connected to the fuse box. That’s backwards. The battery should be connected to the A side of the shunt, fuse block to the B side

 

Ground point from very back of cab with dsp and one amp connected that runs through firewall into battery and to my second grounding point under passenger seat and that grounding point continues on opposite side of truck through firewall to a couple of spots underneath the hood via 1/0 gauge then I’ve got several grounding points on starter transmission and a couple oem spots underneath truck all the way back to the bed with 4 gauge ofc for my switch panel bed lights and other leds back there

 

Oh that’s what I thought the diagram said as well but I blew the hell out of my main fuse when I tried it in reverse the first time. Big arc scared the shit outta me lol.
Idk why this shunt is throwing me off so bad. I’ve wired everything else in this truck with little to no issue whatsoever

 

So do I need to run a jumper to all six of my lugs on negative battery post and to the chassis ground from the smaller shunt terminals?

 

You will never be able to make the shunt/amp meter work like you have it wired.If you disconnect your shunt, I bet your amp doesn’t shut off because it’s getting its ground through the frame which is connected to the battery.
To fix the amp circuit the amps neg needs to be connected DIRECTLY to the B side of the shunt and no where else.
All the grounds have to be isolated, because of that it maybe easier to move the shunt to the positive terminal.

 

I was afraid of that. So could you walk me through or explain how I should go about switching it to the positive side?

 

As is I believe it’s picking up my under hood lights my rear switch panel with USB ports, 12 volt socket and my rock lights only

 

You just wanting to monitor everything connected to the Blue Sea fuse block? If so, put the shunt in-line with the positive wire feeding it. Looks like it need a continuous hot and a switched.

So.. wire battery Pos to A side of shunt, then B side of shunt to fuse block.
Then come back off the B side of the shunt and run the whatever is creating the switched hot, then run that into the switched side.

 

I’d like to monitor the whole truck electrical system if possible