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98 K3500 won:t fire


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maglisn
New User

Dec 14, 2013, 2:50 PM

Post #1 of 9 (3085 views)
98 K3500 won:t fire Sign In

98 K3500 Chevrolet, 7.4L. installed rebuilt 7.4L, can"t get spark at plugs. Checked all grounds, have power to coil. Scan tool shows trouble code p0336.


Hammer Time
Ultimate Carjunky / Moderator
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Dec 14, 2013, 3:05 PM

Post #2 of 9 (3076 views)
Re: 98 K3500 won:t fire Sign In

That's a crank sensor code. You likely don't have any injector pulse either. You'll have to troubleshoot the crank sensor circuit to determine what the problem is. Make sure you didn't bend the pins over in the plug when you plugged it in.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



maglisn
New User

Dec 14, 2013, 3:22 PM

Post #3 of 9 (3071 views)
Re: 98 K3500 won:t fire Sign In

crank sensor has power to the pink wire, Trying to find out what the values of the other 2 wires. The pins are good.


(This post was edited by maglisn on Dec 14, 2013, 3:32 PM)


Hammer Time
Ultimate Carjunky / Moderator
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Dec 14, 2013, 3:30 PM

Post #4 of 9 (3065 views)
Re: 98 K3500 won:t fire Sign In

That really doesn't tell you a whole lot. The correct way to do this is with a lab scope. You need to determine the integrity of the other 2 wires back to the PCM and be able to read the signal where they connect to the PCM.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
Ultimate Carjunky / Moderator
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Dec 14, 2013, 5:33 PM

Post #5 of 9 (3053 views)
Re: 98 K3500 won:t fire Sign In

Pink is 12 volts with key on
Purple is sensor ground and will have less than 0.1 volts with key on while back probing connector.
Yellow is sensor signal and should have 0-12 volts while back probing the connector and cranking the engine. If your using a volt meter the voltage is going to be averaged out depending on cranking speed. You can also turn the crank by hand to see the true 0 and 12 volt signal on a volt meter. HT is correct that an o scope is the best tool for viewing hall effect sensor signals.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


DanD
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Dec 15, 2013, 10:24 AM

Post #6 of 9 (3034 views)
Re: 98 K3500 won:t fire Sign In

Just a thought here; but was the crank sensor reluctor ring installed when the timing cover went on?



It has happened to me when the machine shop missed it when they did a rebuild on a 4.3lt. Cost them a second timing cover and a whole bunch of labour to diagnose and then install the reluctor ring. LOL
Dan.

Canadian "EH"






maglisn
New User

Dec 15, 2013, 3:52 PM

Post #7 of 9 (3016 views)
Re: 98 K3500 won:t fire Sign In

f
Found the problem, Crank sensor air gap was too wide. Thanks for all the help.


DanD
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Dec 16, 2013, 4:58 AM

Post #8 of 9 (2997 views)
Re: 98 K3500 won:t fire Sign In

What the reluctor on the work bench to wide an air gap???

Just joking; glad you found the problem.

Dan.

Canadian "EH"






Sidom
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Dec 16, 2013, 8:03 PM

Post #9 of 9 (2980 views)
Re: 98 K3500 won:t fire Sign In


In Reply To
What the reluctor on the work bench to wide an air gap???



Thats always such a crappy feeling......Got it done, cleaning your hands with a rag, getting ready to fire it up, do your final checks, drive it and your done. Only to walk over and see _________ sitting there on your tool box...... Shocked Shocked


(This post was edited by Sidom on Dec 16, 2013, 8:04 PM)






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