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Discussion Starter · #1 ·
Hey All,
I was pulling my camper to the ocean (29' Jayco Jay Flight) and had almost made it to the camp site. On the highway i went to pass some traffic and hit the pedal a bit in HEAVY-TOW (nothing crazy or floored) to get the rpms up to pass when my transmission threw 2 codes. P0700 and P0735. Naturally i pulled over, cleared the codes on my CTS3 after googling what they were and the problem went away (i wasn't in towhaul mode like an idiot) and had no more issues towing the camper and babied the truck to the site, drove around a bit at the ocean and even switched the DSP5 to my normal #4 driving mode. I did have the trans fluid flushed about 7500miles ago, i do regular maintenance on the truck. I had some motor work done on my truck and it's been doing some goofy things sporadically. I can't electric start my truck due to the truck saying the hood latch is open, i bought a new hood latch, put it in, same problem so i just disconnected the hood latch so i wouldnt keep getting the hood ajar ping while driving. Also when the hood latch was connected, if i put my windows down and hold it a second to long when the window is completely down it would ping the hood ajar, the hood latch tells me the hood is open until i pull the latch to open the hood. So that's the back story. I have reached out to a well known allison trans guy to have the trans built, probably won't hurt to have it built for the truck mods I've done, but my question for the forum is this.. the guy that performed the work on my truck didn't put die-electric grease in the clips no longer used, there's a couple under the hood and a couple for the exhaust no longer used, so should i grease the un-used clips? I reached out to the forum awhile back about re-grounding the truck and how to do it but i can't seem to find my model truck (2015 GMC 2500HD LML Denali) on the reaponse i got and how to upgrade the ground wiring. I read and read this forum and some say the big 3 points, others say 2 for GM trucks, i have 6AWG wire, and am capable of grounding the truck but just don't know where to other then the battery on the negative side.

Now that I've typed this novel, i need help with grounding for my truck, where and how to do it properly and also should i grease the un-used clips? Could a ground issue be the reason for the TCM throwing that code as I'm having weird electrical issues?

2015 LML GMC Denali
165 GPH Airdog 2
HSP DELUXE INTAKE AND Y-BRIDGE KIT
P1 Racing 4" full exhaust
MBRP 4-6" Tip
Cognito Leveling Kit
DSP5 Switch
CTS3 Monitor
Fleece CP3K Conversion
 

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When you say 'clips' are you really talking about wiring connectors? If so, a little dielectric grease to prevent corrosion is fine. These electrical connections aren't bearings, no grease pushing out, etc.

The main thing about grounding is to make sure all the main ground points have been cleaned and very lightly greased with di-electric grease (just to help prevent corrosion, not to make the electrical connection better) when re-assembled. A shiny clean metal-to-metal connection is required. You can replace the ground wiring with larger diameter wires, better terminal connectors. Make sure the engine block to battery wiring is enhanced and then other ground points, such as the firewall ground point, run to the engine block. Frame grounds to the engine block. You don't need several grounds cables on your batteries, one is just fine as long as it is a good one unless the factory has designed more than one ground wire. I believe my passenger side battery has 2 grounds coming to the battery.

Some trucks have a circular device ( I forgot what it is called) where the grounding cables pass through and it tells the ECM how much electricity is being used and the ECM uses this information to keep the batteries fully charged. If you wire grounds around (not through) this device, the ECM doesn't get the information needed to correctly handle the charging.
 

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Discussion Starter · #3 ·
Thanks Ron,
Yes i mean the factory wiring connectors. I know there are 2 along the frame on the passenger side for the stock exhaust and DPF system and 9th injector im assuming and they are exposed to the elements, i do have them ziptied up but moisture is still able to find its way there. I live in the DelMarVa area and we get all types of weather and i don't want that to be a short or the reason im exsperiencing these electrical "glitches". I want to upgrade the ground points with heavier gauge wire, heard horror stories of guys jump starting cars and it shorting the TCM. i just dont know where the factory ground points are other then the goofy one under the front speaker by the windshield which is known for issues, i just haven't pulled that apart yet. Thats my dilemma. And i was curious as to know if this is a possibility, ground issues on why my tranny "glitched". I re-installed a factory ground-band from the firewall to the block but thats all I've upgraded. Did you upgrade your grounds? And if so.. anyway you could give me the cheat sheet and where the stock ground points are? I do have that voltage/amperage regulator you had asked about. I think most new GM's do.
 

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Download the electrical drawings for your truck from gmupfitter.com. There are many grounds throughout your truck. If not grounded properly, it can feed back and cause random stuff to happen, just like you are describing.

There is at least one full drawing for the grounds alone.

Sent from my SM-A705W using Tapatalk
 

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Good advice by Blue06Sierra. Here is a link that will get you a little closer to the Electrical manual for your year and model of truck GM UPFITTER - Body Builder Manuals

I have not done any upgrade to the grounding in my truck, but I have removed and cleaned all major ground points as a part of my service. With the exception of the ground points at the speakers. I'll wait until having some problem that points to that one.

I believe I installed some rubber plugs (not sure that is the correct terminology) for my modification, but I don't have any DEF, so no worry for me there. Yes, you could and maybe should, use a liberal amount of grease to help keep those items from degrading.
 
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Discussion Starter · #7 ·
Blue06Sierra and Ron, i appreciate all your guys help. I was able to find the schematic to a specific ground point and even pictures closely related to they physical locations. This is something I'll tackle this upcoming weekend and I'll update and repost my personal pictures and experiences in hopes it helps the next guy.
 

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Those electrical drawings are priceless.

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