Woes with a 2004.5 LLY Dmax repeated P0089 Fuel pressure regulator codes.

SRGN said:
That's not good. Verify that the meter doesn't have an offset. 70 millivolts may not sound like much, but it's huge in electronics.
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Checked resistance on the 2 wires to the FPR. 0 resistance, also check every other pin on the connector all others show resistance.
Weird thing I noticed.
On the blue connector to the ECM
Pin# 37(Yellow) - Fuel Pressure Regulator Solenoid Control and Pin# 51(Yellow) Fuel Pressure Regulator Solenoid Control show no resistance to each other.
Pin# 40(Purple/Wht) - Fuel Pressure Regulator Solenoid Supply voltage and Pin# 54(Purple/Wht) Fuel Pressure Regulator Supply voltage show no resistance to each other.
2 connections for each wire to the ecm but only one wire at the connector itself.
Why the 2 wires for each Are they going to different places?
 
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The wires for pin 40 and 54 are tied together at splice 142.
 
Figure out why there's voltage on the ground, it will likely lead you to the problem. May even be one of the wires to the FPR partially shorted to the shield in the cable.
 
SRGN said:
Figure out why there's voltage on the ground, it will likely lead you to the problem. May even be one of the wires to the FPR partially shorted to the shield in the cable.
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That was my next check, tear into the engine side harness and separate the wires to the FPR and see if anything changes.
 
The damn wires go into this shrink crap, then after that they are inside a yellow with green stripe cover.

Also the yellow solenoid control wire has .07 volts while running. .02 volts KOEO


 
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I grabbed voltages off every pin on the connectors going back to the ECM.


This is the wiring is back to ECM so short or issue is on that side and not in engine harness, right ?


















 
Mechanical aspect of these FPR issues.
I cut one of the FPR's that seized up in half. This plunger doesn't move(blue arrow).
This is the case with all the FPR's I have changed out except one and the one that still moves I think is good but
it was off a parts engine and I didn't know the history on it so I tried it.


 
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When your low reference is reading the same as sensor inputs, the computer sees those as 0 volts. I'd start adding auxiliary grounds, if you don't feel like tracking down the bad wires. Tap into the ECM ground leads, and add a ground to where the ground cable attaches to the block. I'd also rebuild splice 171.
 
Rebuild splice 103 while you are at it.
 
SRGN said:
When your low reference is reading the same as sensor inputs, the computer sees those as 0 volts. I'd start adding auxiliary grounds, if you don't feel like tracking down the bad wires. Tap into the ECM ground leads, and add a ground to where the ground cable attaches to the block. I'd also rebuild splice 171.
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I tried this yesterday, tapped into the big ground on the ECM, ran it right to ground, no change.

Gotta find S103, no clue where it is.
What do you think if I start pulling fuses? Would that maybe help locate what circuit it is?
I verified it has 0v with key off.
 
#18 in this image is the location of splice 103.

 
I put a stethoscope on the FPR of my buddies truck tonight, could hear the same vibration so I guess it's normal.
 
Putting the stethoscope on the other truck ain't helping your ECM grounds.
 
If you backprobed the other truck and verified that the grounds read zero it would be good, though. I do worry about your meter picking up EMI and reading it as voltage, sending us chasing a ghost.
 
SRGN said:
If you backprobed the other truck and verified that the grounds read zero it would be good, though. I do worry about your meter picking up EMI and reading it as voltage, sending us chasing a ghost.
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He won't let me do that, doesn't want his truck getting jacked up. Some friend :LOL:
 
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