Suspected starter failing

Waffle34 · April 10, 2023

2018 5.3 non flex ~40K miles

Replaced battery about 4 months ago due to similar behavior:

Saturday woke up went to start my truck, key in turn to run everything lights up as normal. Turn key to start and nothing, hear a faint click but everything else goes dead. Release key everything lights back up normally. Try again and same thing. Wiggle shifter in park, same thing. Try again and fires right up.

Drove all over saturday and sunday no issues. Tried to remote start this am and nothing. Tried again and sounds like i got half a crank outa it before nothing. Tried key, same thing as above with no crank but full dash lights. Ran and got my battery tester both old school load resistor and needle style and modern electronic one. Both show 100% charge and good with 12.5V on it. Tried key a few more times and started up but cranked slow. Runs fine- volt gauge shows slightly above 14V on dash.

No dash lights or errors. In the past since ive owned the truck and the factory battery like 2-3 times i got the "low battery voltage start immediately" warning as it was cranking but havent seen that since i replaced the battery.

I plan to after work today see what i get on the signal wire when trying to crank at the starter and verify connections are clean and tight.

BUT google searching sounds like the starters are junk on these. If you were to get a replacement what brand would you go with? OEM? Any recalls or TSB's about this issue?

Waffle34 · April 10, 2023

got my starter out. its part# is 12681473. Braided cable is all green and rusty nuts going from solenoid to motor - Will take the motor apart tomorrow see what internals look like.

every parts place says the oem one is 12695760 for my make model year trim engine.

Ive heard theres an older style junk version then a redesigned good version. I assume the currently for sale everywhere (12695760) is the updated version (higher part#).

Waffle34 · April 11, 2023

Motor appeared to be OK inside, more carbon than i expected but likely break-in of the brushes. I did remove the battery cable to engine block ground and it had some starting of oxidation. Also removed the other smaller battery cable to frame ground (thats right behind the front tire where ****** aka salt water gets kicked up wtf gm...) and wirewheeled that clean. Did same on passenger side that goes from the wire harness bundle to frame. Plan is to coat bolt threads (that are exposed lol) and mating surface between ring terminal to frame with conductive grease - Fills in any micro scratches and pits with carbon filled grease so conducts and keeps moisture and oxygen out so it cant rust or corrode anymore. Then coat the outside with fluid film...

If im doing all that i want to remove clean and do the same to the braided cable from firewall to wherever that other end goes (anyone know?). Any other known ground issue areas? Absolutely hate weird ground problems on anything.

Waiting on replacement starter in the mail...

Waffle34 · April 13, 2023

So followup for anyone finding this thread in the future.

Yes the new starter (# 12695760 ) fits and works so much better. I have never heard that truck crank over so fast and strong sounding and i bought it new in 2018. Word of advice: i mixed up some dielectric grease and graphite to make conductive grease which i then slathered between the mating surfaces on all the nut connections (that were only finger tight right outa the box...) and on the bolt threads. I also made sure to smoosh as much as i could into that braided wire. A) it wont ever rust or corrode and B) the graphite fills in any scratches and pits creating a near 100% connection.

Once the old starter was out i did clean the negative battery terminal cable to engine block connection (jackasses buried it behind the starter so take it off and clean it while you can get to it - mine was starting to corrode) with a wire brush along with the neg battery terminal to pass frame rail connection with a wire brush. Then put more conductive grease before assembly for same reasons as above.

I also removed, cleaned, greased the drivers side frame rail ground (both of these are right where the front tires kick up everything from salt spray to rocks - engineer needs a swift kick to the ass for that idea).

I also plan to remove, clean, and apply conductive goo to the block to body connection on the firewall. Also run a dedicated ground from battery negative post to firewall connection with some 8ga wire- Can never have too many grounds especially on these trucks and as far as i can tell there isnt any direct ground from battery to body (where ya know like 14 computers are grounded...) - it always has to go thru something first which is asking for trouble.

You can buy conductive grease - Tweco is a brand ive used and works great but its not cheap and i havent found it locally (used in welding applications usually and many places can get it in a day or two). Dielectric grease and generic powdered graphite (which you can find at hobby stores or hardware stores for pinewood derby cars or graphite lock lube) is relatively cheap and you dont need a whole lot to go a long ways.