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Low voltage to fuel relay

Camocoaltrain
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Camocoaltrain

Camocoaltrain

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I have a 2000 3500 5 speed. New built engine. Currently getting about 9 volts to fuel relay. Truck started and ran upon engine install but oil change place arced alternator on oil filter. Injector pump was fried, so I replaced. Traced back to computer. Sent off twice and got same result. Installed computer on another truck, same result, have to jump pins for relay to start engine. Sent off to Auto computer specialist this time, same result. Fass comes on and works fine but injector pump won't create pressure while this relay is getting low voltage. Please help. I have used this site for testing wires and can only come up with computer failure but after repairing 3 times now with two companies, I'm at a loss.

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LorenS

LorenS

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I wish I could help with this! Hopefully someone will come along with a short list of items to check.

 

My guess out of left field is that there's a bad wire splice, corrosion, etc. somewhere upstream of the relay.

 

Or, the proverbial bad ground.

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Mopar1973Man

Mopar1973Man

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image.png

 

If you look there is only a fuse in between the fuel relay and the VP44. Which is the same fuse that powers the ECM, PCM and VP44 all share the same power source. (Red/white) Then the (brown/white) is the trigger to the relay. So my suggesting is change the #3 fuse in the PDC and then change the relay. 

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W-T

W-T

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Camocoaltrain,

 

Please show the method and the device of "how you are measuring" this DC voltage. 

Allow us to see your analytical procedure...photos of your connections to your DC multi meter and the display. Let us see how you connect your probes.

 

 

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LorenS

LorenS

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Where did you measure the 9 volts at the relay?  Was that the red wire (connection #30), at the red/lt green wire (#87), or somewhere else?  What did you use for a ground when measure the voltage?

 

Did you measure the voltage of the brown/white wire (#86)?  If you aren't getting 12V at #86, it may not be enough juice to consistently operate the relay.  If your G102 ground was bad, I would imagine you'd be having other problems, too.  That's the ground for (#85) the relay.

If (#86) doesn't have 12V or more, does (#36) coming out of the ECM?  I imagine it does if you've sent off the computer that many times!  But, that wire may have a corroded connector, or bad spot in the wire.

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Dieselfuture

Dieselfuture

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32 minutes ago, W-T said:

Camocoaltrain,

 

Please show the method and the device of "how you are measuring" this DC voltage. 

Allow us to see your analytical procedure...photos of your connections to your DC multi meter and the display. Let us see how you connect your probes.

 

 

Great to see you hanging around here once in awhile, hope things are going good for you. Thanks for your knowledge and contribution to keep our gremlins under control.

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W-T

W-T

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I too was wondering where @Camocoaltrain was in the fray of this topic.

 

Also, @Dieselfuture thank you for the acknowledgement...my dismal record of activity due to circumstances will improve slightly and my recent absence from the site was a technical error that has just been corrected with the assistance of @Mopar1973Man...hence, I will be here to annoy the participants with zealous intent in the pursuit of technical excellence regarding the CTD platforms.

 

Cheers   

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dripley

dripley

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On 5/10/2021 at 1:57 PM, W-T said:

 

I too was wondering where @Camocoaltrain was in the fray of this topic.

 

Also, @Dieselfuture thank you for the acknowledgement...my dismal record of activity due to circumstances will improve slightly and my recent absence from the site was a technical error that has just been corrected with the assistance of @Mopar1973Man...hence, I will be here to annoy the participants with zealous intent in the pursuit of technical excellence regarding the CTD platforms.

 

Cheers   

Good to have you back. With your help I made the gremlins leave me alone for a good while now.

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W-T

W-T

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Hey @dripley...thanks, it's gratifying to know efforts are awarded in simple ways...I feel successful when others have achieved results from helpful hints.

 

Now if @Camocoaltrainwould chime back in with his findings perhaps an answer could be discovered and assist him in this task. 

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