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Everything posted by BrentH

  1. @clubba: I was only going by what the original factory installation has listed saying 220 amp alternator with the dual battery setup. This could be due to the loading if you have extras like the 120volt outlets or maybe it is linked into the charging management system in the truck? I would assume 170 amps would be sufficient? It maybe worth a bit more research .......
  2. For anyone wanting to install the second Battery and has a 6.6 gas 2500HD with a main fuse block (the one on the main battery) that has a 250 amp fuse here is a wire diagram: this is the connection to the control relay from the BCM (drivers side, left under the dash). Clip wire and solder in a splice that will control the relay (2 in the drawing). This violet/brown wire applied power after the truck is started. It also runs a relay for the HVAC system. the spliced in red wire runs on the firewall at the same place you put in the wires for the UpFitters switc
  3. Going back a page or two I mentioned that the kit was listed on the Canadian GMParts site for $65 and just had the title “switch”. My dealer ordered it in with the part number for the jet black interior- keyless start. It came in complete. I have it all installed and pulled 4 conductors out the fire wall for my options. All in it was something like $63.99 plus tax CDN. Must be a pricing glitch but I will take it!! Took about 3 hours to get it all in. Thanks for all the posts!!
  4. @Rozz522: for all intentions the second Battery is doable if you can make a few changes to the original trucks charging system: 1. If for some reason (like mine) you have a 250 amp alternator fuse connection at the main battery fuse block you can upgrade a 170 amp alternator to the 220 amp. I did this - it was not a big deal. 2. You need a second battery that matches the original battery to keep charging reasonably equal 3. On the Auxiliary Battery you need an isolation relay that cuts out the Aux Batt during starting. 4. You cut the 30 amp con
  5. So after wasting a lot of time looking for a wire needle in a haystack: I took the X50A fuse block all apart (this is the one under the hood). F79 for the Auxiliary Battery relay is 10 Amp and is connected to nothing. No wire comes from that terminal out of the fuse block. There is no pin for the the fuse to connect to and the fuse is just in there holding a spot. Same with fuse F80. I am no longer looking to hook up the aux battery isolation relay control to anything “original” as the truck does not have the wires necessary. I am simply going to run the contro
  6. Here is the mess - no connection or even the wires according to the drawings. There is some confusion as the power from the under hood fuse panel (X50A) is from fuse F79UA and the wire is red/white but one drawing has it as red/blue - argh! Going to tape it back up and will Find another power source for the isolation relay. the next pic is what I have set up with the power as per the other drawings from the upfitters and the parts for the truck: I still have to hook up the 30 amp fuse but would like to have the battery charging properly first
  7. Working on the “then” right now. Not looking encouraging on my part. Just got the loom peeled back. Was hoping to see a couple (3) wires terminated right there in a small coil. It is a tough spot. Will post a couple pics after. the white arrow in the 30 amp feed from your Aux battery to the trailer plug. if you do not have the Aux Battery the feed comes from the engine compartment fuse block and is “on” all the time. You could kill your start battery if you leave your trailer plugged in and it has some power consumer on board.
  8. No worries @wxman. Pics are super. You must be very flexible to get in there. your second pic is excellent- I will explore that connection. It is totally not where I would have checked. thank you !!!!
  9. @Wxman You are awesome! so the grey relay in your second last pic and also in the second pic has 3 wires coming into it : red/white, black and a violet/brown The violet/brown comes from the BCM and energises the grey relay once the truck is started. The red/white comes from the fuse block right there beside the battery (X50A) and once the truck is running the grey relay closes and White/Red powers the isolation relay in picture . The black is just ground. There are a pile of errors in the GMUpfitters electrical drawings. Your assembly contradicts the wire harness from the pa
  10. Hello, So i have everything installed except for the one control relay that is supposed to come off the body control module to allow charging to take place after the engine is running. A wire from the fuse panel is for the power to close the isolation relay. Some where in the wire harness should be a plugged 4 conductor with three feeds - I cannot find it anywhere - "should be" under the auxiliary battery tray.....frustrated....... I installed the upfitter switches - that job was a couple hours, everything clicked easy. If anyone has the au
  11. My son just checked the truck and the battery connection to the lug I was asking about in the previous post-it is dead - no power going to it. So Hmmmmm....What is somewhere in the truck that has no power and then why is it there?
  12. Hey @Rozz522, I ordered part number 84663447 - J Block Auxiliary Battery, 84471670 Junction Block Cover I still have to get under the hood (I am away till next week) and clarify a few things: "Supposedly" under the battery mount could be the connector X136 which would then allow you to run to the relay KR81 (Auxiliary Battery Relay 1) from this relay you go to the KR79 (Auxiliary Battery Relay 2) that supposedly comes included in the J Block Auxiliary Battery? I ordered the 220 amp alternator so I have to wait for parts to arrive. I have some questions
  13. @Gr8FrozenNorth : did you ever complete this operation of adding the auxiliary battery and increasing the alternator capacity? I just purchased a 2021 2500HD LT and they "forgot" to install the package or couldn't due to missing parts. Anyway I have the parts ordered and a new 220 volt alternator on the way and will be doing this mod in a few weeks when everything arrives. My truck arrived with the 170 Amp Alternator but has a 250 amp fuse for the alternator on the main battery. For a 170 amp alternator this would normally be a 175 amp fuse. For some reason my fuse b
  14. What I think is correct the the 2500HD LT for the Aux Battery circuit: On this drawing though, F79UA 10A is misnamed and actually called the AUX BATT/SCRPM in other locations of the electrical schematics
  15. So here is the crazy thing: On my truck: 2021 2500HD 6.6 gas LT I requested the 220 amp alternator and aux battery - It didn't come that way - no aux battery and a 170 alternator BUT: My fuse panel on top of the regular battery is NOT the correct one for the set up as fitted (according to GM parts) my fuse block is part number 84646133 this is a fuse block from a 1500 diesel with a 220 amp alternator. So my fuse block (X50D) has the following F1 - 250 Amp connected to 170 Amp ALT, F2 - 175 Amp connected to Fuse Bock X50A F3 - 400 Amp connected to Starter Motor T
  16. For you guys installing this, I have a 2021 2500 HD and things look just a bit different on the electrical side and I have a question/favor to ask if any of you have the second battery: Can you post a picture of the open fuse box on the 2nd Battery? The GM part # is 84663447 and I cannot get a clear answer whether the box contains the relays and fuses or it is just bare and you need to add. From the cost it seems it should have the guts. Also, I went to order the kit 84942073 for the 9L7 ( upfitter switches) and it seemed way to cheap - like it was $65 ? that doesn't sound lik
  17. The GM Upfitters site has the instructions I do believe. There is a hole to drill for sure and it does provide a guide to the connector. for some reason I cannot get to the site right now due to a privacy thing from google
  18. Is there anyone out there that can take a couple pictures of the second battery installation? Perhaps the cover off the fuse block and along the wire run? I ordered my truck to come with the second battery and they did not put this in, I instead got the powered lift and drop tailgate. This feature is not available (don't think so?) on your typical LT model so it was a bit of a surprise. The added battery is so I can power things in the back cap while I work out of it when doing on site carpentry type things. I have been through the GM Upfitters and the auxiliary bat
  19. That is the problem, you need to have a z71 or higher package+ to get that option. I have an LT and could not get the option unless I have the rear cargo camera - useless for me as I have a truck cap - not worth paying for. GM sorta shooting themselves in the foot as this would be a sweet "standard" edition to the LT plus packages
  20. Looking for the same - will post if I can get some information
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