I am in the throes of replacing the crank seal, tappet cover gasket, radiator, and intercooler. With the good access, and since I plan to keep this truck, I figured I'd replace the battery cables. No real issue just tired of the corrosion and poor stock terminals.  I ordered a nice pair from K Suspension but the install instructions leave a lot to be desired. Information is limited from other sources, anyone every tackled this job? One part that seems daunting is the many sensors that share the wire loom with the power cable going to the starter. Getting that apart and keeping it all straight must be a challenge. Any advice is appreciated. 

 

2001 2500 Quad Cab - Bone stock 

Update on my truck.  About a month ago I started having the TC lockup and apps code appear again.  I just cleaned the ground on the alternator negative lead, replaced the military style terminals due to corrosion, cleaned the battery posts, and battery cables ends, then slathered them all up with the anti corrosion spray.  It fixed everything again. 

 Good contact on both power and grounds are a must. Glad to hear you got it sorted out.

I hope that fixed it, but don’t be discouraged if it comes back. Sometimes disconnecting the batteries can temporarily clear up issues when the capacitors drain. If it comes back make sure you do the full WT mod, get great batteries, and test your alternator again. 

I finally completed my WT mod. The first part of it had solved my TC lookup issues but I was having other issues so I completed the mod. I used a 150 amp fuse in this plastic housing I got off amazon. Reused the old charge lead cable, cut into sections. The fuse is easy to access and I have two extras in the cab. Grounded the ground wires from the front wire loom to the back of the gear cases. Everything has been working great. I still have my lift pump on a manual switch but for now its all running good.  

Yes I did the WT mod and parallel battery mod at the same time.  This recent round was due to neglect on my part.  I washed the engine several times without slathering up the terminals.  I'm running Costco battery's and they tend to seep at the posts.  I should be due for batteries next year, I'll search for recommendations.  I don't think I want to go the cheap route again. It's clear to me this little electrical tunup will be necessary on a regular basis.  Although this time I did slather up all connection points to the alternator, batteries and grounds.  I've been using the purple terminal protector, I think permatex makes it.  I see some of you are using oil.  Anything to keep the moisture out and keep them sealed up.  I should probably revert back to dielectric grease, nothing beats that stuff for preventing galvanic corrosion.  

Be aware running parallel ground leads is difficult to diagnose. Being it's possible to have one ground fail and the parallel lead will cover up the failure and hard starts. This is why I do not suggest this. Factory lead position is fine and diagnosing is simple being there is no bridge cable. Just be aware.

I stand corrected, I actually did not do the parallel battery mod.  I was conflating upgrading the alternator ground lead to the battery with the parallel battery mod.  Passenger battery has another 1/0 lead going to passenger side engine block. 

 

I did have yet another flare up of the check engine light, this time no TC lockup issues, but a TP signal low code.  I pulled the APPS bellcrank and all and removed the apps sensor plug, sprayed silicone lube and plugged it in and out a few times, cleaned the mounting surfaces and cleaned up the bolts, and slathered them up before tightening them.  lastly I cleaned up the grounds going to the timing gear housing.  No problems since, and it's been 3 days.  Moral of the story:  keep them clean.