Join Date: Dec 2017
Location: Central Arizona
I'll ask the obvious,, how old are the batteries? The batteries are connected in parallel to give AMPLE amps to the starter. If one battery is old and weak, it drais the other.
(edit, I just caught the mention "they are fairly new",, here in the desert SW 2 years on a cheap battery is good,, 3+ is a miracle,, a top dollar battery seldom lasts 4-5 years here. The change from hot to cold / cold to hot usually takes then out. Also a AGM battery like the Optima red or similar is a POOR choice for a truck battery. They do not absorb amps at nearly the rate a normal wet cell LA battery can. Hard on the alternator, and leaves batteries less than fully charged)
I'd first take BOTH batteries and have them load tested. If one is down, REPLACE THEM BOTH. To avoid electrical issues in these trucks replace the batteries as a PAIR.
Second have the alternator tested at a good electrical repair shop. The bobo's at the discount parts houses with a meter usually know LITTLE about what the equipment is telling them, and it won't tell you much ON THE TRUCK anyways
Third,, what aftermarket equipment is there??? If there is a retro-fitted alarm and remote start or a hacked audio system by a 10th grader working as a stereo installer, you definitely need to start there and search for all power wires that could connect to EITHER battery ans the positives are connected at the starter.
2004.5 Silverado CCSB LLY
Sinister EGR delete,
S&B air box and up-sized S&B intake mouthpiece,
CAT converter delete,
ATP 5 stage tune - Edge CST w/ EGT and backup camera,
5" AFE Power full exhaust kit
Airlift 5000# bags w/ on-board remote compressor
Just a nice CLEAN stock truck for towing the toys to the playground with a back seat full of grandkids
Last edited by MarvDmax04.5; 10-02-2019 at 06:35 AM.