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.

My apologies for taking so long to reply, but it looks like these instructions require for the engine to start. I have no spark at all thus the engine wont run at all in bypass mode or not. If I'm missing something in these instructions please let me know thanks!!

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.

I'm currently living 45 minutes away from where muly truck is (because of Christmas vacation) but i'm trying to go to a nearby salvage yard tomorrow to pull and entire engine wiring harness, which contains the wires from ECM to ICM. Is replacing the entire harness myself a good idea?

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.

I tried unplugging the tan and black wire like you said and still couldn't get it started. What's next? Is my next step still replacing this wire? If so how hard will that be i'm not a wiring expert and actually hate doing anything with wiring normally, but i want to fix this without hiring someone else if possible. Also i talked to a person at a local AutoZone and he said any wire running to the ECM should be grounded but when i checked every wire i checked was hot. I do not know if this means anything but could it possibly be that my ECM connectors are shot?

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?

With my truck still at college almost an hour away itll probly be a couple days before i can get to testing that because im working full time during xmas break but if i do and the pickup coil is bad then it will be as simple as replacing that without having to do a bunch of wiring right? Ive lifted my cap a couple times but never really took time to look at the pickup coil. And do you reccomend getting a brand new one or would that be a part im as well off getting from a salvage yard? Thanks!

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 .

I also must have forgotten to mention that i have checked my coil for spark (disconnected the coil to distributor wire and put a spark plug in it and held it against the engine block to see if it sparks) and couldn't see any spark. I don't know if i just missed it or if i did it wrong but it seems like the problem is somewhere before the distributor possibly. The ignition control module was the first thing i replaced BTW.

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.

Okay, so upon inspection i found the pickup coil was bad. It was a stock coil so it was riveted instead of screwed but no problem i just replaced the whole distributor. Now i have spark but i'm not getting fuel. My guess is i just haven't ran the truck in so long the fuel pump went bad but i'm looking for any tips and or suggestions. Thanks!

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 has been about 6 months since it ran. I was able hear the fuel pump kick on just last week but today i couldn't. Would a bad filter cause it to stop pumping?

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.

I'm going to do a pressure test this weekend. i just want to know this in advance so i'm not having to wait for a reply after the test. If the pump is not working will the gauge show 0 after attempting to prime the pump?

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 think that's it because i have replaced the filter and put fresh gas in it and still got no fuel and i couldn't hear the pump kick on. so i'm guessing it's the pump because i have also checked the relay and fuse. I'm sure once i do the test I will realize there is something else i forgot to ask, lol. but for now i think that's all. Thank you so much you've been a huge help in trying to get this old girl back on the road!

I actually do have one more question. If i do go after the fuel pump how do you recommend doing it? I have watched videos on both pulling the bed back and dropping the tank. To me dropping the tank seems like an easier method but i have also seen people cut a hole in the bed. Cutting the hole seems simple enough and easier for one person but do you recommend it?

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.

So today i ran a pressure test and it showed 0. I replaced the fuel pump and the relay and still nothing. I completely forgot what you said about checking for power at the tank and that must be my problem and thats all on me for forgetting. Now that im back at college where my truck is ill be able to work on it more so how do i go about making sure i have power?

Okay, we're going to skip forward here since you've replaced the fuel pump relay already. There should be 2 hot wires (12 volt) while cranking, where the relay sits. So take it out and check the pins for 2 for 12 v cranking. Now there could be corrosion in fuse panel where the relay is too, so you'll have to check it. If there isn't 2 hot pins at the relay, then go to the back of the ECM and check pin F6, it will be dark green/white. You will have to find it according to color. This wire should be 12v while cranking as well. Here's 2 wiring diagrams to help. Make sure to pay attention to wire condition also, you most likely have a broken or corroded wire. Check around where you have been working on the truck so far, that you didn't move any wires or hide the problem. Since you had the fuel pump running before. Check all the ground wires near the pump on the back of the frame too. The 2 thicker wires at the fuel pump are power and ground, the power is the thick grey wire.

My fuel pump relay isn't in the fuse box its on the firewall directly in front of the ECM in the engine bay. I don't think the location should matter as long as i am finding the right wires. right?

No it shouldn't. Only wire color matters.

Okay, i now have power to my fuel pump and can hear it priming when i put the key in the on position, but i'm still not getting fuel into the engine. I assume it's either my injectors or a clog in the fuel line, but again i don't want to go spend more money and not have it work.

Okay , how did you get power to the injectors and can you take a picture of the throttle body with the injectors in it for me? The 2 second prime is a different circuit than the engine running circuit. You can hook a test light to 'battery' positive and check the injector pulse from the ECM while cranking., since the ECM grounds the injectors to pulse them. How long has it been since the engine last ran? Injectors can seize up if it's been sitting for along time. I'm assuming you have fuel pressure now?

It has been about 6 and a half months since it ran. I'll take pictures of the throttle body and injectors and send them to you when i am back in town where my truck is. but right now i'm at home to watch the Superbowl, lol.

Okay, start with verifying fuel pressure, and watch the injectors in the throttle body and watch for fuel while cranking the engine, either the injectors are closed up or the ECM is shutting down the injectors for some reason. Recheck for power at the injectors and make sure there is an injector pulse coming from the ECM. You can use a test light for both these tests. In my previous post are the instructions for testing the injector control. Enjoy the super bowl.