the only thing i see that is questionable is the resistance on the ground side,

Clamp your jumper cables to the starter body and to the engine block and try to start the truck.

With a good battery, voltage will drop to around 10 or 11 bolts while cranking, the starter can put a 200 to 300 amp draw on the battery

Is your truck acting up and not starting or is it starting normal while you've been testing?

The voltage drop while cranking at around 1 volt can be the meter being dampened and not reacting fast enough to show the true drop

Neal

 

It's been acting up. Atleast 4 out of 5 start attempts I get the 1 loud click now. (And anytime I test something and it does start, I just shut it off and test again). Because it seems most important to test when it's not working verses when it is. BUT, I think I finally found it. A neighbor came by and helped me move wires while trying to start it. (I had thought of this but to be as honest as possible, have a healthy fear of being electrocuted.....but he did not. He called me a wimp in a nice way and said go try it lol).

End of story.....when we bend the small cable going to "S stud" for solenoid 1 way, it starts every time and when bend it the opposite direction it doesn't start every time. I unwrapped some tape that goes around the end of that smaller hot cable and there is a break in the metal crimp/terminal at the base of it. Now to figure out best way to fix it. (I can not find a replacement "pigtail" as I call them where they sell you the end you need to splice a new one in its place). Seems like I will just have to find a similar terminal/eyelet and same gauge wire to make my own........any thoughts?

 

sounds like you and your neighbor may have found a possible cause,

I agree, find an eyelet that fits and some of the same gauge wire and replace that section an see if this resolves the starting issue.

good thinking to move the wires around while starting, fix the wire and report back and let us know if this was the issue

Neal

 

Well I was wrong. Replaced that cable end going to solenoid stud on starter and it still does it. (Starts about every other time and get the 1 loud click every other time)

So now I need to do those 2 different tests using jumper cables. Just to make sure I understand correctly.

Test one, connect one end of jumper cables to battery and other end to main positive starter stud and to starter housing. (This will bypass my cables and if fixes the problem, proves it's in my cables somewhere.....and if it does not fix the issue, it eliminates the cables as a possibility)

Test two, I only use 1 jumper cables from each end. Connecting the ground cable on one end to starter housing and ground cable on other end to engine block somewhere. This will test to show if it's the starter grounding to bottom of engine is the problem. (If it fixes it, I have to remove starter and sand down bottom of engine block.....and if it doesn't fix it.....it's deffinently not the starter grounding to engine as the problem. Is this correct?)

Any test to eliminate the ignition switch, after market remote start, or relay out of curiosity? (Does getting power at the "S stud" for solenoid, when key turned..... eliminate them as a possibility or no?)


Man I appreciate you more than you know Neal!

 

For the first test use the red jumper cable to the positive post on the battery to the positive lug on the starter and the ground cable on the ground post of the battery to the starter housing.
If this helps then move to the ground side, connect both cables to the starter housing and both to the engine block somewhere

for the remote start usually the brake switch will defeat the remote start so try starting your truck with the brake peddle pushed, it really depends on what type of remote start it is. Depending on the type of anti-theft it has the remote start will have to be programed correctly to work. Does the remote start work when used?

The ignition will either provide voltage to the small purple wire or it will not, it the truck has voltage on the small purple wire when commanded to start then its probably not the ignition. The test to watch the voltage when trying to start would tell you if there was an issue, if you loose voltage while cranking then its on that side of the starting system

The relay would also be on the control side of the starting system, if the relay was to fail likewise the neutral safety switch it would stop sending the voltage to the purple wire

The fact that it clicks lends me to believe its on the main power side, when you try and start the truck it puts a very large amp draw on the main power side and this is when the weak points will show up.

DC meters that will measure up to 600 amps are somewhat expensive and most don't have one laying around but for this type of testing would be valuable. Your voltage test between the positive and negative cables at the starter only showing a 1 volt drop while trying to start the truck lends to indicate that the starter is not seeing the full load of the engine. I would expect to see the voltage drop to near nothing if there is a bad connection at the starter or a bad cable.

Neal

 

Performed both jumper cables tests and no change. (The jumper cables I got from my dad were new, never used but only 6 gauge cables, where as I read 2-4 gauge are ideal). Does the tests not making any changes, eliminate the power cable and ground as cause? Do I need to test with higher gauge cables to be sure?

Other things I feel important to remind of.

1. Whenever it acts up and won't start for MANY attempts.....tapping on the starter housing from under the truck (tapping the bottom of the starter) seems to help it start. The first 20 times I ever did this, it worked everytime. Only 2 times ever (out of maybe 30-40 times over 6 months) did lightly tapping on starter NOT work to get started and we had to wait an hour or more, try again and then it would work. To be extra clear I always had to do roughly 3 light taps WHILE she tried to crank for the trick to work.

2. Also seems to be affected by heat somewhat. First few months it seemed like it only ever did it when hot. But more so lately not always the case. Just like first few months light tapping on starter always worked to get it to start, but now more so lately, not always. A few times it didn't work.

I put 2 brand new GM starters on already. Both acted exactly the same for #1 and #2 listed above

Other things I feel could possibly be clues.......I put the first starter on months before transmission was rebuilt. As far as I remember, we had no issues after putting first new starter on until after the transmission rebuild. After that we have had MANY issues. (The rebuild is another whole story to get into with the guy being dishonest and incompetent). He only replaced the 3rd and 4th clutch pack instead of actually rebuilding the trans like we discussed, by later saying it's "standard" to only replace the "hard parts that are bad" and there was something on the bill about "replacing shifter cable.". After getting back, we noticed the lights by the shifter in the cab worked. They hadn't before that because we never knew there was lights there to indicate gear prior to that. But they worked for one day then an odd burning odor, then they didn't work anymore.

Oh.....also the cluster had several gauges that didn't work when we first got the truck. (The common bad stepper motors). We sent it in and had all stepper motors replaced and upgraded blue LEDS. Got the cluster back, everything worked great, then literally 2 days later it went in for the trans "rebuild".......and when we got back, the cluster worked when you first started the truck, but within a few minutes.....all the gauges would just "freeze" in place. Not be all the way down or all the way up like the bad stepper motors cause, but just "freeze" wherever they were.


Thoughts?

 

Using the jumper cables as described will validate that the cables are good,
Making sure there is 12 volts at the small wire (Purple) while cranking and not losing 12 volts validates the control circuit from the ignition
Checking for voltage lose while cranking validates that the starter is getting the needed voltage to crank if the lose is less than 2 or 3 volts, GM says it needs to stay above 10 volts

Check the voltage going into the solenoid and out of the solenoid while cranking is next, this will validate that the solenoid has good contacts (have you checked this?)
Having to tap on the starter usually indicates that either the starter brushes or the solenoid is bad or something is wrong with the stator or rotor

I'm struggling with believing that you have had 3 bad starters especially GM or ACdelco brand, I've had very good luck with these


Neal

 

Ok, I will retest the purple wire getting 12 volts while cranking and retest voltage at Starter while cranking as well. (I too feel like some tests need repeated as it just seems crazy nothing is "showing itself" by this point).

My multimeter usually shows the battery itself having anywhere from 12.8v-14v (with the truck not running). I know the 12.8V is great, but seems like the 13.5v or more is "too high" without the truck running and the alternator part of the equation. So wondering if my multimeter is accurate? Can you have much over 13v at battery terminals without it running on a 12v battery? (Feel I should take battery in and have it tested to make sure it doesn't have a bad cell, even though volts are always good and it's a new battery 1 year ago) and also wonder how accurate the old multimeter I have is.

How do I check the voltage going in and coming out of the solenoid exactly?

And Its only been 2 brand new GM starters but still even then, it's extremely hard to believe there would be 2 brand new GM starters bad out of box, but not only bad out of box, but both with the exact same problem/acting the exact same way. To me, that really screams it can't be the starters. Now I know tapping on the starter working is most often a sign the starter is bad/going bad......but that usually only works a few times at most before it goes out completely.......not working 40 times over 6-9 months. So that part always makes me circle back that it's a loose connection/poor power wire/bad ground. (And again, the part about 2 brand new GM starters both doing this, further says it's not the starters to me)


​​​​​​Finally, is the a way to test the neutral safety switch (I think it is on the transmission) as again it all started after trans taken out and put back in twice? Also the cluster not working also started at exact same time. (After he "rebuilt" trans). Just feel it HAS to be related somehow........pinching wires, hitting the sensor on trans, even bumping a wire or routing the harness barely differently bending a weak wire in different direction, causing a intermittent short.

 

a normal automotive battery should show 12.6 volts when fully charged, this is based on the number of plates/cells in the battery, 6 cells at 2.1 volts per cell.
The voltage will be higher when the engine is running and the alternator charging.

On the solenoid there are 2 lugs with 2 cables connected, the main power cable comes form the battery to the supply side of the solenoid, the second side is power to the starter motor. The solenoid is just a large set of contacts controlled by a low draw/amp side (control side). When you turn the key the control side of the solenoid is provided with 12 volts closing the large contacts (solenoid) and allowing voltage to pass to the starter motor.

I was also including the original starter and the 2 you replaced, and I agree that it is unlikely that you have gotten 2 bad GM starters but its not impossible I guess

The neutral safety switch is in series to the purple wire, if not working it will not pass voltage to the solenoid through the purple wire

Neal,