Error code 42, no spark

Hello, I'm Danny.

I've attached a step-by-step picture diagnostics for Code 42 below. This will help you to troubleshoot before buying more parts or something else. Hope this helps and thanks for using 2CarPros.

Hello, code 42 is referring to the EST bypass circuit, it is the tan/black wire in this diagram. This wire controls the timing advance from the ecm. The ecm is seeing an open circuit or short to ground on this wire. So you're going to have to check this wire from the ignition module to the ecm before changing anymore parts. If this wire is touching the frame somewhere or is broken it is going to mess with the ignition timing and cause a no start.

Well, it would probably take more time to replace an entire harness, than fix the one wire that's shorted out. The EST is the wire by the distributor that has the little plug you would take out to set the base timing. What you would want to check is anywhere the harness has a contact point with the engine or chassis. These are the spots that wear threw because of vibration from the engine. I would go after a single wire versus changing the whole harness. Try unplugging the est timing plug and see if the truck starts, let me know if it does. It's the tan/black wire.

Okay, so going back to your original post, you said you've replaced everything except the distributor. It sounds like the pick up coil in the distributor is bad. Do you have an automotive test light? I can explain how to test the pick up coil with a test light. There's a purple/white wire coming from the ignition module, with your test light hooked to battery negative, and back probe this wire, your test light should pulse while cranking. I'm assuming you have replaced the ignition module as well?

The pick up coil is located inside the distributor, so getting a remanufactured distributor from the parts store is the safest bet. A junkyard distributor will not last long. Also take off the distributor cap and make sure the distributor spins while cranking. Since you've replaced every part except the distributor, that's most likely the issue, you can test the ignition coil to see if there's a signal. Test light connected to battery positive, and the negative side of the ignition coil should pulse while cranking. Same as the purple/white wire at the ignition module, this wire should pulse while cranking as well. Test light connected to battery negative. These tests will give you direction in diagnosing this. Also check the engine to body ground wires and make sure there's no corrosion or bad connections.

The pick up coil in the distributor is the main input for spark and fuel injection. If you connect your test light to battery negative and back probe the purple/white wire at the ignition module, you should get a pulse on the test light while cranking. This is the reference high signal wire, if there's no pulse then most likely the pick up coil is not functioning. You should also get a pulse on the negative wire of the ignition coil.

Good to hear, those pick up coils go bad pretty easy. How long has it been since it ran last? I would think if it's been over a year, it just has bad gas. Replacing the fuel filter and some fresh gas might be all you need to do at this point. You can run a fuel pressure test to rule the pump out. There should be a test port on the fuel rail.
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

It can be a number of things, but doing a fuel pressure test is where I would head next. There could be a corroded fuel pump relay that's not working any more, any number of power issues. You can actually rent automotive tools, like a fuel pressure test kit. From AutoZone and advanced auto. You just have to pay the price of the tool, but they give you your money back when you return the tool. Making sure your fuel system is functioning correctly is crucial. A fuel filter issue will show up on a pressure test.

https://www.2carpros.com/articles/how-a-fuel-pump-works
https://www.2carpros.com/articles/how-to-change-a-fuel-filter
https://www.2carpros.com/articles/how-to-test-a-fuel-injector
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator
https://www.2carpros.com/articles/how-fuel-injection-systems-work
https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester
https://www.2carpros.com/articles/how-to-use-a-voltmeter
https://www.2carpros.com/articles/how-to-check-wiring
https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit
Here's some extra information to help diagnose this no-start issue.

It can show 0 psi or close to it, depending on the problem. The 2 second prime is actually a different electrical circuit, so you want to make sure you have cranking pressure as well. If there's an electrical problem you may have the prime but no cranking pressure or the opposite. If you have 0 psi, you'll need to check for power and ground back at the pump connector, if there's no power (12 volts) back at the pump, you'll go to the fuel pump relay next and so on. If you don't hear the pump prime, which you should, you can go right to the pump and check for power. Bang on the fuel tank as well, it may kick start the pump while cranking. If it starts while banging on the tank, the pump will still need to be replaced. Anything else you might question during these tests?

I don't recommend cutting any holes in anything, especially around fuel vapors. You could end up with a fire, just not safe. Dropping the tank is recommended way of replacing the pump. But make sure you have power at the tank while cranking, you could end up changing the pump and not fixing the problem. Just to be sure.