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sprinkles08
sprinkles08, Chrysler/Dodge/Jeep master tech
Category: Dodge
Satisfied Customers: 21601
Experience:  ASE Master and Advanced Certified, Chrysler/Dodge/Jeep Master Certified, Trans and Hybrid Specialist
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I have a question about a no spark/ maybe no fuel problem

Customer Question

Hi i have a question about a no spark/ maybe no fuel problem with my 98 dodge ram 1500 v8 2wd.
Submitted: 9 months ago.
Category: Dodge
Expert:  Randall C replied 9 months ago.

Hello, what is missing? have you sprayed some carb cleaner in the air intake to see if it runs on the spray/starting fluid? have you tested for spark? what do you mean by starter coil?

Customer: replied 9 months ago.
hello randall this truck has been sitting for a few years and want to get it running again so where i am now is .... testing for spark as carb cleaner did nothing and i have no spark at the plugs i have new crank sensor and new cap and new ignition coil sorry for the typo before ...seems i have no power to the ignition coil asd relay is fine and switched with other new relays to make sure. im getting reading out on the crank sensor harnes but thats about where im at right now kinda lost with where to look next
Customer: replied 9 months ago.
also my brother lost the keys a few years ago so the ignition tumbler is missing so starting with screw driver right now hahah dont want to spend the cash if its just gonna have to be scraped but i very much hope not lol
Expert:  Randall C replied 9 months ago.

well, this is a lot of new/added information. what do you mean by no power to coil. What wire are you testing and how?

Customer: replied 9 months ago.
well i have tested the coil from the two wires that plug in to the coil from the bottom if im thinking right the green wire is 12v wire and not getting a reading
Expert:  Randall C replied 9 months ago.

I need to know details , are you testing the green wire key on or while cranking , is mUST be while cranking

Customer: replied 9 months ago.
cranking as it only gets power while cranking .
Customer: replied 9 months ago.
also tested all fuses with test light and all seem to be good as both sides light up while in fuse box
Expert:  Randall C replied 9 months ago.

Unsure and rather involved diagnosing this, The ASD relay is not being entergized if your tests are correct, I need to opt out and open the post to the other experts, One should be along soon to help

Customer: replied 9 months ago.
ok thanks
Expert:  sprinkles08 replied 9 months ago.

Hello and welcome to JustAnswer!

Odds are the powertrain control module is not awake. Does the fuel pump run when the key is turned on, do the fuel gauge and voltmeter stay down when the key is turned on?

Customer: replied 9 months ago.
Hi and thank you...No I can not hear the full pump running and yes both gauges do stay down when key is turned on. I've noticed I am getting low voltage to ignition coil...only about 2 volts with engine cranking.
Expert:  sprinkles08 replied 9 months ago.

The PCM isn't awake then.

What you'll need to do is disconnect the black PCM connector and use an incandescent test light to test it's powers and grounds. The power feeds are on pins 2 and 22 (key on) and the grounds are on 31 and 32.

Customer: replied 9 months ago.
Ok....I believe there are 3 different connectors that go to the PCM...could you provide a diagram of which connector you are wanting me to test?
Expert:  sprinkles08 replied 9 months ago.

You're testing at the black connector.

Customer: replied 9 months ago.
Not to sound stupid...but the black connector from the PCM to what?
Expert:  sprinkles08 replied 9 months ago.

You're checking the power feeds on pin 2 and 22, the grounds on 31 and 32.

Customer: replied 9 months ago.
Ok I will look into this as I am at work and get back with you.
Expert:  sprinkles08 replied 9 months ago.

Great!

Customer: replied 9 months ago.
ok checked power power wires in 22 and 2 with test light and both are ok and same with the grounds in 31 and 32 ....
should i be checking my 5v reference circuit for a short in one of the sensors in that circuit couldn't that be pulling power down only getting 0,46 in 5v circuit in all sensors ? if so do u have a complete wire diagram for this truck from battery to sensors to ignition coils and to pcm thanks for any info.....
Expert:  sprinkles08 replied 9 months ago.

Yes, you'll need to test the 5v reference circuit for a short to ground as well as the sensor ground circuit (black/light blue) for voltage. A short to voltage on the sensor ground circuit will also take the PCM down.

I have all necessary service information but cannot post directly from it due to copyright.

Customer: replied 9 months ago.
Ok if you can not provide diagrams (which I understand why) could you please give a bit of a more detailed explanation of the 5v circuit? I need to know if there are two 5v circuits and what sensors are on each circuit. How would you suggest is the best way to test a 5v circuit ?
Expert:  sprinkles08 replied 9 months ago.

The 5v reference goes to the cam, crank, throttle position and MAP sensors. It should be a violet/white wire, you'll test the circuit for a short to ground with the PCM and sensors unplugged.

Customer: replied 9 months ago.
Okay thanks for that information but wouldn't a short to ground cause a high voltage reading? What if one of the sensors are shorted in the 5 volt circuit shouldn't I do some kind of volt check while I'm plugging the sensors and still connected to the PCM?
Expert:  sprinkles08 replied 9 months ago.

A short to ground would cause voltage on a circuit to drop.

If a sensor was internally shorted then the PCM would wake up when the sensor was unplugged.