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    2018 GMC 2500HD Denali Duramax

BrennanK's Achievements


Enthusiast (2/11)



  1. I believe the gray wire for the courtesy lamps (X61A, X3, pin 29) which I have un-pined and re-crimped with a piggy back wire is a PWM signal. I didn't realize it was a fading/PWM signal. My old 2005 which I came from was not, so I just swapped accessories over to my new truck without thinking much. The electromechanical relay I am using (Bosch style) doesn't really like the PWM signal. It chatters really badly until the voltage reaches a high enough duty cycle where it finally will seal in. It is the same when turning the lights off where it will chatter until the voltage is no longer present. It seems like most people just drive their additional lights directly off that gray BCM wire without a relay, but I have some higher power lights which require the use of some sort of relay. I am hoping there is a specific relay or device I can use to 'filter' the PWM signal to my existing relay. I can't imagine that the PWM signal is very good for an electromechanical relay long term. The relay is also located under the hood with the rest of my accessory fuses and wiring, so it needs to be able to withstand that environment. I was thinking of maybe adding a diode and a capacitor in series with pin 86 on my relay, but I just don't know what size to use or anything like that. I am a little out of my element on this one. Maybe someone better with wiring skills than me can assist (@pgamboa).
  2. You are correct, however at least in my truck (and other HD trucks from what I've seen) that setting is not persistent. The Parking Assist System will re-enable at each key cycle. That setting is only for that one key cycle. Believe me, if that setting worked I wouldn't have came up with this modification to disable it. I like the factory parking assist system, I just want to enable and disable it on my terms.
  3. Switch works fine, I just don't want to push it every single time I start my truck to disable the system. I want to push it only when I want it enabled. The MyLink settings are not persistent. If you change it, on the next key cycle it turns back on. You cannot disable the seat and the sound, you have to have one enabled, and I do. I want the system to function as intended. just not on by default.
  4. My 2018 has the factory parking assist feature on both the front and rear bumper and it works great - when I want it to. What I run into more often is 'nuisance' alarms. I park in a very tight garage so my seat is rumbling the whole time I am pulling in or out of my garage. I also back my boat down the ramp at the lake several times a week, which requires unplugging the electrical, so it yells at me the whole time I am backing up the trailer. I got tired of the factory 'default on' setting of the parking assist so I devised a way to make it 'default off' with the option to enable it when I'd like it enabled, much like the lane departure warning system. The way this works is when the relay I added is energized via the run/crank circuit in the upfitter junction block it closes it contacts for a configured time of 2 seconds. That contact is wired to ground and then to the park assist disable switch circuit. When ground is supplied to that circuit in the truck the system is deactivated just the same as if you pushed the button in the center console. To re-enable it simply push the button in the center console again. Pretty simple solution that costs under $30-40 bucks and it easily removed again to revert to the factory setup. Here is what you'll need: Custom time delay relay - I used a DROK relay on Amazon OEM upfitter connector (X7) - Connector on Mouser 15547106 (OEM P/N is 13924036 and is no longer available) OEM terminals (or wire taps) for tying into the park assist disable switch - also available on Mouser Here is the process: For the physical connector that plugs into the X7 socket on the junction block you'll need: Aptiv 15547106 (because the OEM P/N is no longer available) The connector is the right design, but it is physically keyed differently. The correctly keyed connector is out of stock everywhere, but with a razor blade you can cut off the second key that prevents it from fitting. Here the connector is before I cut it: Here the connector is after I cut it: Here is the cavity in the junction box in the driver footwell: Next you'll need to wire up the relay module. I chose to use a connector here so I could easily connect and disconnect it. When this module is disconnected the system works as it does from the factory. Here is the wiring diagram I whipped up: As far as X7 connector terminals to order you'll need the following: Function Location Connector Pin Aptiv Terminal Required Run/Crank Power X61A X7 11 35063087 Ground X61A X7 10 35063087 If you choose to remove the factory crimp for the park assist wire and re-crimp with a pigtail you'll need the following pin. Alternatively you can just splice into the wire using your preferred method. Function Location Connector Pin Aptiv Terminal Required Park Assist Disable X61A X5 45 33385008 Here are some general notes from the project: 1. X61A junction box is located in the passenger compartment, under the instrument panel to the left of the brake pedal 2. The park assist system is momentarily ground side switched, supplying a ground reference at connector X5 cavity 45 will enable/disable the system 3. The accessory power on connector X7 cavity 11 is factory fused at 15 amps in the left hand instrument panel fuse box at fuse #30 4. Time delay relay configured for close on power, delay for off at 2 seconds Attached are some OEM wiring diagrams, component locations and system operation descriptions so you can better understand how the systems works and how we are modifying it to make it work the way we want. Park Assist - Power, Ground, Serial Data and Control (UD7 or UD5).pdf X61A Junction Block - Instrument Panel Top View.pdf X61A Junction Block - Instrument Panel X5.pdf Park Assist Disable.pdf
  5. Well I think I got it. I had an order into Mouser and figured what the heck and added on a few of each of the OCS 1.5 and 2.8 terminals in stock to see if they worked. It was worth the $5 dollar gamble... If anyone wants to do the wiring themselves and save a few bucks over buying a pre-terminated block for any upfitters switches and power this is what you need: For the physical connector that plugs into the X7 socket on the junction block you'll need: Aptiv 15547106 The connector is the right design, but it is physically keyed differently. The correctly keyed connector is out of stock everywhere, but with a razor blade you can cut off the second key that prevents it from fitting. Here the connector is before I cut it: Here the connector is after I cut it: Here is the cavity in the junction box: As far as the terminals I found 3 that will work. For cavities 2,3,5,6,8,912,13,15,16,18,19 use Aptiv 33385008 - this is for all the smaller cavities, so that terminal is only good for 20-16 AWG probably. For cavities 1,4,7,10,11,14,17,20 use Aptiv 35063087 or Aptiv 35063083 depending on your wire gauge. Both fit the larger cavities. All these parts are in stock at Mouser and you can order them in quantities of 1 or more, so no bulk ordering required. For under $10 bucks you can make your own connector, have a much cleaner look and save a few bucks.
  6. I am not controlling the signals listed above, the truck is, they all originate the BCM. I use them to power the coil of relays to turn on and off my accessories. My truck has the parking assist default to on, it is ground side momentary switched. So I have a time delay relay that when it is energized it will close it contacts for 10 seconds. I am using the two wires from the X61A:X7 to power the relay and provide a ground reference to the common on the relay. Then you can wire the NO contact to X61A:X5:45 to disable the parking assist on truck startup. This basically defaults it to off, but if you push the button in the center console it will turn back on. The other two are pretty easy. I have additional backup lamps that are controlled by a relay that will close it contacts when X50A:X5:M8 goes high. I also have puddle lamps installed that I want to control via the interior courtesy lamp circuit. So I have another relay that will close its contacts when X61A:X3:29 goes high. I don't need switches for these accessories because they are all controlled by the truck already, just need the signal wire from BCM to fire my relays. I prefer to do it this way because then I can power all my accessories from one spot and fuse and wire everything how I see fit. I bought some of the service terminals, so I will keep you informed if they work. Thanks for the help!
  7. Unfortunately they do not work very well when you have a diesel Denali with all the switch spaces taken. Additionally, I am not using switches at all, hence why I am trying to tap into wires. If it helps, these are the wires I am using: Description Junction Box Connector Pin Accessory Power X61A X7 8 Ground X61A X7 10 Park Assist Disable X61A X5 45 Courtesy Lamp Signal X61A X3 29 Back Up Lamp Signal X50A X5 M8 Only 2 of those are part of the up-fitters connector you listed and of those two only the ground is actually pined out. Furthermore the wires that are pinned out are part of the OCS 2.8 connector size, so I couldn't even move the terminals to a new cavity because the other cavity I need is the OCS 1.5 size. That kit is designed to be used with the RPO code 9L7 which my truck doesn't have and I don't have any interest in adding because it doesn't do what I am looking to accomplish.
  8. I appreciate the effort, but that is exactly the type of part I am trying to avoid. I am not using the factory up-fitters switches, so I will be using different terminals and cavities on the connector. I have a custom up fitters solution I am using that I made a while back. I just need to tap into some wires in the X61A junction box and the method I prefer to use for tapping into wires is to re-crimp the factory wire with my new additional wire.
  9. Thank you for the information! I am glad I am not the only one struggling to get information. Aptiv is essentially useless unless your a major customer too, hopefully you having a service account will help. Out of curiosity, how did you discover those service terminals? I cannot really find any cross reference to the Aptiv part. Either way I will probably buy a few just to see - I'll let you know what I learn. Thanks again!
  10. I am looking for some help tracking down Delphi (Aptiv) terminals. On my GMT-800 Duramax truck I was able to always get them (and all the connector parts as well) directly from Mouser Electronics. Mouser was nice because they often had a minimum order quantity of 1. I recently got a K2XX truck (2018 Duramax) and I am starting to transfer over some of my custom up-fitter accessories and I am seriously struggling to get parts. Almost all of the wires I need to tap into are located in the X61A junction box beneath the steering column. That is also where the factory up-fitter connector is located, the X7 connector. From what I understand this truck uses the OCS series connectors in those spots and the connectors are unique because they're a mix of OCS 1.5 and 2.8 terminals in one connector. The OEM connector for the X7 location is Aptiv 13924036 (per attached TSB), but I cannot find that anywhere, Mouser says it is obsolete. The Aptiv 15547106 will work (and is available) if you slice off one of the guides molded into it. I understand the approved GM 'solution' is to use GM 19328970 which is already terminated with leads. However I don't like to use butt splices if I can help it and that doesn't help me tapping into a few other connectors on the X61A junction box that are already factory terminated. So my real question is, does anyone know where I can buy the terminals for the OCS 1.5/2.8 connectors? Everywhere says they're obsolete, on crazy back order or a minimum order of 10,000 or something. The interesting part is even Aptiv themselves don't have these connectors or terminals in their catalogs, almost as if they're GM proprietary. I'm specifically looking for Aptiv 13849930 and 13849935 for use in the up-fitters X7 connection block. These terminals are used in a few other areas that I would like to tap into as well and I prefer to cut the factory wire and crimp on a new lead and the factory wire and re-insert it into the connector. Not to mention it helps me avoid buying lots of GM's overpriced single wire leads and using lots of butt splices. Any guidance would be greatly appreciated. I never expected to have such a hard time getting information and parts for this truck; it was super easy to get all the connectors and terminals for my 2005 before. Up-Fitter X7.pdf
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