Another starts and dies.....

[watchamakalit]

The manche has me scratching my head. I have the dreaded start and immediately die issue. I have had this issue before and fixed it with a good cleaning of the ballast resistor terminals.
 
This round is different. The truck will start with the key in the start position, but as soon as the ignition is turned back to run the truck dies. I have fuel pressure in the ignition switch start position only. No fuel pressure in the run position of the ignition and no prime from the pump. The B+ latch relay and the fuel pump relay have tested good and are reciving constant power. I can jump past the relay and the pump will run and create pressure on both circuits. The ballast resistor tested good. And I have tried bypassing completely with no change. I have completed all of cruiser54's tips.
 
I believe the ecm is not signalling the relays to cycle but I can hear a relay in that area cycle during what should be the prime circut of the pump cycle. I have not tested the ecm pins to see if its providing signal to the relays. My question is where does tge ecm recive signal to tell it that its time to engage the propper relay? Does it read that off the cps? Or is there some other sensor responsible for this? I am pretty sure it is a faulty ecm but have no way to verify this other than dropping $150 on a possibly unnecessary part.
 
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[Minuit]

Got a multimeter with an ohms function? I'd be starting at the ignition switch. Look for a burnt up connector. If that looks ok, it's time to grab the meter and follow the chart on the right:

 

 

[Minuit]

Pin assignments, from left to right.

       I-3                     S

G-1

         B-3     B-2     B-1

 

G-2          A             I-1

[watchamakalit]

I will have to check that. Guess I didnt think about ignition switch since everything else worked normal.

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[Minuit]

That's just the first stop, but none of this stuff can work right in the RUN position if the switch isn't doing its job properly.

[watchamakalit]

Everything checks good on the ignition switch. No burnt wires and everything tested good.

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[Ωhm]

Need to take some voltage measurements. Use the following connectors callout. D1 and D2 are located under the hood, right side of engine compartment. Should have yellow covers on them.

 

D1_5 Battery Voltage (B+) Hot at all times.
D2_4 Battery Voltage (B+) Hot with KEY in RUN or CRANK position.
D1_6 Battery Voltage (B+) Hot with KEY in RUN position (only 2-3 seconds). This ones tricky, because its time limited.

Use battery negative terminal as DVOM ground.

[watchamakalit]

D1-5 no voltage ever
D2-4 got in run and start
D1-6 no power

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[Ωhm]

D1_5 is Fuse Link G (green). D1_5 feeds D1_6 via the Fuel Pump Relay. Check Fuse Link G.

[watchamakalit]

D1_5 is Fuse Link G (green). D1_5 feeds D1_6 via the Fuel Pump Relay. Check Fuse Link G.

Can you be more specific as to the location of the fusible link?

 

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[Ωhm]

Fusible Links are located on the Starter Relay (large threaded stud).

[watchamakalit]

I just probed all the fusible links and they all test good

 

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[watchamakalit]

Hold the phone i think I might have located an issue. I started tracing the wire from the diagnostic connector and found this buried in the harness.....

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[Ωhm]

Yeah, that what we were working toward. Looks like Engine Control Harness Splice_E. If it all red wires you found it.

[watchamakalit]

Yeah, that what we were working toward. Looks like Engine Control Harness Splice_E. If it all red wires you found it.

Sure is. I'm waiting on the soldering gun to warm up now

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[watchamakalit]

I FREAKING LOVE THIS FORUM!!!!!!!!!!!


Wires stripped, corrosion removed, soldered, heatshrinked, and truck running. You guys are awesome.

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