No spark, no fuel

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Do you know how old the codes are? If you erase the codes, do the codes come back? Sometimes multiple codes can mean computer or computer wiring issues?

Did you check primary voltage at the coil?

I will check the codes and get back to you.
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
GONZO1234
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The codes came on when the short happened. The check engine light was not on before. I did a coil test yesterday the voltmeter was low.
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
GONZO1234
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And if I delete the codes. They come right back
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
JDL
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I checked the codes, they are for various sensors, voltage too high. As an example, check the ref voltage to the throttle position sensor, key on. The wire color is violet with white tracer, ref voltage around 5 volts.

If you want to trace primary voltage to the coil and go at it that way, we can do that. I already gave you the wiring color, dark green with orange tracer. That voltage comes from asd relay, That doesn't mean the relay is faulty, there fuses involved and a computer ground circuit.

I'm not saying that the computer is faulty, I'm just trying to be thorough. I can't see anything from here?
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
JDL
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Does the battery have a full charge? Sometimes when hunting problems, it's not uncommon to run the battery down.
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
GONZO1234
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The throttle sensor has around 5 volts
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
GONZO1234
  • MEMBER
  • 15 POSTS
Battery is charged
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Exactly how much voltage is going to your coil?

You can place digital multimeter leads across battery posts, have helper crank, what is reading? Usually it shouldn't go much below 10 volts. The actual reading on the positive side of the coil should be close to the same.
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
GONZO1234
  • MEMBER
  • 15 POSTS
I did it yesterday and it didn't even get pass 1 volt
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
JDL
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One volt isn't enough, have to backtrack circuit. Check voltage to and from asd relay. Check fuse and voltage to fuse circuit, fuse 6--30 amp, fuse 9--10 amp. One fuse circuit is hot all the time, the other goes hot with the key on.
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
GONZO1234
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I'm not around the truck right now but I will do another coil test tomorrow and see what the volts are. Thanks for your help I'll get back to you ASAP. Do you think I should have the pcm tested?
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
JDL
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At the moment, I'd try to follow the voltage. Let us know when you get a chance.
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
GONZO1234
  • MEMBER
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So I did the coil test again today and the green/orange wire well cranking had about 10.03 for about 2seconds then it dropped to about 0.40. Did the black wire also and it had about 12 volts.
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
GONZO1234
  • MEMBER
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So I checked all the pins at the powertrain control module connectors. A2 has power but no ground.A31 no power but has ground. A4 no power but has ground.A32 no power but has ground.A22 has power but no ground.C11 no power but has ground.
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
JDL
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Our wiring diagrams show c1 and c2 connectors, but, using c instead of a, everything you posted about those terminals appear to be correct.

When you first turn the key on, no crank, the computer will ground the asd relay for a couple seconds, then no ground without cam and crank sensor signal.
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
GONZO1234
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I have power to crank and cam.
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
THADRIAN86
  • MEMBER
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  • 1998 DODGE RAM
  • 5.9L
  • V8
  • 4WD
  • AUTOMATIC
  • 210,000 MILES
Recently rebuilt the engine and the transmission and re installed. Put in a cam headers and intake. Truck ran about 30 miles then abruptly shut off. Engine cranks but no spark or fuel. Replaced the PCM and it ran again this time for about 3 miles came back home and shut it off only to not have it start again. Jumped out the fuel relay and it sends fuel. Jumped out the asd relay as well and you can hear something clicking i'm assuming the distributor? But still no spark. When the ignition is turned on 12v comes up on the coil side of the asd and fuel relay however when you put a voltmeter on the relay the 12v dissipates to nothing when put under load for the relay coil. When I remove the relay it goes back to 12v but it doesn't have enough current to activate the relay. Is something shorting out the PCM or is there something else I should be looking at?
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
GONZO1234
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Also if the terminal appear to ok then what next
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
CARADIODOC
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To get you started, it sounds like you're seeing proper operation but you aren't aware of it. When you turn the ignition switch to "run", the Engine Computer turns the automatic shutdown, (ASD) relay on for one second, then it goes back off. That is done to insure fuel pressure is up for starting, in case it bled down over days or weeks. That relay gets turned on again during engine rotation, (cranking or running), and the computer knows that by the signal pulses it receives from the crankshaft position sensor and the camshaft position sensor.

On models that use a separate fuel pump relay, that relay is turned on either by the ASD relay directly, or the coils for the two relays are in parallel so both are turned on by the computer, at the same time.

The air gap for the crankshaft position sensor is critical, and since the transmission was separated from the engine, if that sensor wasn't removed first, there's a good chance it got damaged or pushed up a little. That sensor on older engines was adjusted by a thick paper spacer glued to the end to set the air gap. Your design is set automatically by the mounting bracket so it can't be misadjusted, but it can be damaged.

You've already observed you're missing spark and fuel pump. Most people get hung up on the first one of those they find missing, then waste all their time in the wrong circuit. You can try reading the diagnostic fault codes first, but be aware fault codes for these two sensors often don't set just from cranking the engine. They usually need more time to be detected, as in when a stalled engine is coasting to a stop. For that reason, be sure to not disconnect the battery or let it run dead until the codes have been read, because doing so will erase them, then that valuable information will be lost.

To read the codes yourself, cycle the ignition switch from "off" to "run" three times within five seconds, without cranking the engine, leave it in "run", then watch the code numbers appear in the odometer display. You can go here:

https://www.2carpros.com/trouble_codes/obd2

to see the definitions, or I can interpret them for you.

If there are no fault codes related to these sensors, start by checking if the ASD relay is turning on. The easiest way to do that is to use a test light and back-probe the dark green / orange wire at any injector, the ignition coil or coil pack, or either smaller terminal on the back of the alternator. In the rare event I told you the wrong wire color, it is the wire that is the same color at all of those places. A test light works best because it is easy to see from inside the truck, and digital voltmeters usually don't respond fast enough.

You should see the test light turn on for one second when you turn on the ignition switch. If you do, that proves the relay and its circuit are okay, and the computer has control of it. It's very rare to find this part doesn't work. What's important is if the 12 volts comes back when you start cranking the engine. If it does not, it is because the signal is missing from one of the two sensors.

Both of these sensors commonly fail on all car brands by becoming heat-sensitive, then they work again after cooling down for about an hour. This type of failure doesn't really sound like what you have. Typically they work okay as long as you keep on driving and natural air flow keeps them cool. They usually fail when a hot engine is stopped, such as when stopping for gas, then during "hot soak", engine heat migrates up to the sensors causing one to fail.

I had one fail exactly like you described, but it was my fault. To help out a coworker at the dealership, I was replacing transmissions periodically, and I got too arrogant to use the paper spacer to set the air gap on the crankshaft position sensors. It was on my 13th transmission job, the engine quit running two weeks later, and was repaired with a new crank sensor. I'm pretty sure it was just because I hadn't set the air gap properly. That one stopped suddenly, like you described, after running just fine for miles.

Let me know what you find up to this point.
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)
Tiny
JDL
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With engine cranking, the ground for the asd relay should be constant. The ground is controlled by the computer.

When you said the coil had decent voltage for a couple seconds and then went very low, makes me think, the computer stopped grounding the asd relay for some reason.
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Sunday, December 13th, 2020 AT 10:01 AM (Merged)

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