98 K1500 motor swap but no start

I’m still curious about this picture though, I’m sure @Road Trip copied it from GM Service Manual. It is possible that is a different year than my 1996?

My ‘98 doesn’t have it either. I did extensive videotaping during the removal of the motor and my footage shows only those 2 grounds - not a 3rd (#7 in diagram).

Update: spark plugs are out and engine turns free and smooth by hand.

Interesting insight - after I got “ping and dead” the last time, power seems to return if I disconnect and then reconnect my battery? Does that make sense or is that coincidence?

Next step is to disconnect Coil power and ICM power to see if I can get starter to crank motor by jumping the relay.

Question: how do you disconnect power to ICM? Unplug the whole deal or?? Thanks!

I can't remember, but have you swapped in another battery to eliminate it as source?

Keeper said:

I can't remember, but have you swapped in another battery to eliminate it as source?

Click to expand...

It’s a brand new battery bcs that was part of the original problem… thanks

Mmmm…..my 96 and 97 k1500s with 5.7s only have one braided ground cable running from the rear passenger side block to the frame.

After reading this entire thread it sounds like it’s back to a broken cable/wire that is causing an intermittent loss of power.

I have had it happen to me. The battery ground to block cable broke cleanly about an inch back from the terminal that attaches to the block. Took me a month to find it and only then by sheer (dumb) luck.

Do you know the truck will start and run with only the 10 ga ground wire that runs from the battery terminal to the fender? Sheesh….

Thanks everyone for your contribution to the troubleshooting process. You guys are amazing!

@Road Trip here is the update per your protocol in post 46:

1) Recharged the battery back to 100% - CHECK

2) Removed all 8 spark plugs while waiting on the charger to finish - CHECK

3) Remove 12v power from the ICM & Coil. Verify that the engine spins over by hand with no tights spots anywhere in the rotation - CHECK - SMOOTH ROTATION WITH NO BINDING

4) Check cranking fuses. Get the 12v power to show everywhere on the truck. (Parking lights, headlights, radio, fan, etc.) Take note of anything not powering up - CHECK - ALL GOOD - I EVEN VERIFIED THAT I'M GETTING 12V POWER TO THE FUSE BUS AUX TERMINAL.

5) Crank the engine over by manually jumpering power to the starter with the Ignition disconnected. Including NOT losing power to the rest of the truck for 3-5 minutes. NOT CHECK!!!

Even with Coil & ICM disconnected, I still get "Ping - dead" when I manually jump power to the starter. This time, I disconnected the battery and reconnected it and it brought the power back on.

In addition to the above checklist, I also doublechecked all wires and they match the diagrams with good contact - no pinching or compromised wires.

My next step is going to be removing the Starter and bench-checking it to eliminate it as a culprit.

What else do you recommend?

DHud said:

5) Crank the engine over by manually jumpering power to the starter with the Ignition disconnected. Including NOT losing power to the rest of the truck for 3-5 minutes. NOT CHECK!!!

Even with Coil & ICM disconnected, I still get "Ping - dead" when I manually jump power to the starter. This time, I disconnected the battery and reconnected it and it brought the power back on.

In addition to the above checklist, I also doublechecked all wires and they match the diagrams with good contact - no pinching or compromised wires.

My next step is going to be removing the Starter and bench-checking it to eliminate it as a culprit.

Click to expand...

Good work! Glad to hear the first 4 steps passed the inspection criteria. Especially pulling all 8 plugs and being able to turn the engine
over by hand. This eliminates the remote possibility of a hydrostatic lock from either coolant or an injector that's stuck open.

So given the above, Yes I concur with you removing the starter assembly, and with any luck it will behave
just as poorly on the bench check as it did in the truck.

DHud said:

What else do you recommend?

Click to expand...

There are 2 possible scenarios here. Scenario #1 is that for some reason the starter motor picked up
such a bad internal short that it was putting such a load on the entire electrical system that this was
the root cause of all the problems? If the original starter fails on the bench, the new starter goes in,
and all works as advertised, then this must be the answer.

But what if the original starter seems to work fine on the bench? But in an abundance of caution you
buy a new starter, install it, and the new starter acts exactly the same as the original one?

Here is Scenario #2:

alpinecrick said:

Mmmm…..my 96 and 97 k1500s with 5.7s only have one braided ground cable running from the rear passenger side block to the frame.

After reading this entire thread it sounds like it’s back to a broken cable/wire that is causing an intermittent loss of power.

I have had it happen to me. The battery ground to block cable broke cleanly about an inch back from the terminal that attaches to the block. Took me a month to find it and only then by sheer (dumb) luck.

Do you know the truck will start and run with only the 10 ga ground wire that runs from the battery terminal to the fender? Sheesh….

Click to expand...

Casey has shared some hard-won firsthand knowledge about this from his own vehicle. This is
where Shurkey would tell you to measure the voltage drop across each connector while the load
is drawing the full current through it. For example, with a new/perfect 2 gauge cable, if you measured
the voltage drop across the length of that cable while the starter is turning, I would only expect to see
a 0.1v-0.2v drop? (From battery terminal to where the 2 gauge wire connects to the starter.)

Hypothetically speaking, let's say that the 2 gauge cable is made of 24 individual strands of copper,
but 22 of them have broken, leaving only 2 strands still connected. Guess what? Those 2 strands
are plenty big enough to give you a 0.0-0.2 ohm reading on your multimeter, and could probably
pass 5-10 amps no problem. But there would be several volts showing when the starter is cranked
over. And if the cable is completely broken an inch away from the end, that's when you see the full
battery voltage across the cable whenever you try to crank the starter. (And the part that's no fair
is that like Casey said your primary 2 gauge ground cable is bad, but the starter is able to get by
on the woven ground strap that's between the cylinder head and the frame, and from there it
makes it back to the battery via the G101 ground that's on the fender close to the battery itself?

So maybe before you pull the starter you check for any voltage drops across any connectors? And
especially between the high current 2 gauge cables, both positive and ground. Who knows? If you
are lucky all the problems will stay with the original starter and show on the test bench. But copper
is like aluminum, you can only bend it so many times before it physically fails.

****

You know if this was a 26 week old truck all this jibber-jabber about internally failed power cables
would be so much hot air. But on a 26 year old vehicle where a lot of the previous engine bay history
is unknown, we have to take the extra steps to prove each piece of the electrical/mechanical puzzle
is still fully functional.

Speaking of which, IF the starter works well on the bench, then despite the fact that your battery is
new, as a precaution I would want to have that battery load tested just to be sure. At this point,
even the new (virtual) load testers that shout some sort of Van Halen into the battery in order to
check the internal impedance and infer the goodness factor is better than nothing.

Best case is you find some old geezer who still has one of these in his shop, {See 1st attachment}
for this is the real deal put a genuine current load on the battery and see if the voltage flattens
while meeting the challenge. (NOTE: I was classically trained on the industrial strength SUN VAT-40,
but as a hobbyist I get by on the much more affordable load tester in the 2nd attachment.) It's a
carbon pile load tester that helps me identify/remove the weaker batteries from the fleet. It has
never lied to me...

Again, sincere thanks for not taking any troubleshooting shortcuts in steps #1 through #4.
We are simply going to outlast the problem, and maybe even learn a thing or two while we're
at it. (I for one have learned that the FSM line drawing out of Volume 4 of the '99 C/K manual seems
to have an extra ground strap thrown in for good measure. :0)

Best of luck. And be sure to make some time to enjoy Father's Day. With these projects it's
all about the Pace, Grace, & Space.

Road Trip said:

So maybe before you pull the starter you check for any voltage drops across any connectors? And
especially between the high current 2 gauge cables, both positive and ground. Who knows? If you
are lucky all the problems will stay with the original starter and show on the test bench. But copper
is like aluminum, you can only bend it some many times before it physically fails.

Click to expand...

I like this thinking - but how do I test for voltage drop on these lines if I can’t get the starter to engage before everything dies? The “Ping - dead” result is immediate…

DHud said:

I like this thinking - but how do I test for voltage drop on these lines if I can’t get the starter to engage before everything dies? The “Ping - dead” result is immediate…

Click to expand...

You know, if the headlights were unaffected and the only thing we were getting was the "Ping - dead" results, I'd be pretty confident
that it has to be the starter. My gut feeling is that pulling the starter and see how it plays on the test bench would decide it for me.

But if the starter is fine on the test bench then the only variables we have changed are the A) Power cables to the starter, and B) The
battery used to drive the starter. This is when you decide to get a helper to turn the ignition key while you test the suspect cables/connections.
(An old analog meter would stay steady during the "Ping - dead" transient, but would jump if there was an internal cable issue? And of
course with a digital display multimeter it would be harder to see.

It's late, and I'm probably overthinking this. It's one thing to test a cable for resistance out of circuit, but this is only good
for completely good/completely bad (open) scenarios. But on the other hand, testing/measuring the voltage drop of the
electrical circuit while under load is the no-nonsense method to really prove out your older wiring. With any luck the
starter will fail on the test bench and testing for voltage drops will be superfluous?

you may want to pull the battery while you are pulling the starter and have them both tested at the same time. I know its a new battery but i have limited faith in current manufacturers and sometimes you just get a bad one.

If that is the case, relief at solving the problem may be accompanied by strong and sometimes new and different car repair language. Also tools and other random objects may be accelerated towards unsuspecting inanimate objects in the shop.