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So Connector going into fuel pump module control.
I see the yellow and orange wire going into the FPCM and now I need to test it to see if there is voltage and how much? I’m using a multi meter in pictures below but not sure what I’m looking for yet. Also I imagine the car should be on when I run the test correct? Or only ignition on?
I see the yellow and orange wire going into the FPCM and now I need to test it to see if there is voltage and how much? I’m using a multi meter in pictures below but not sure what I’m looking for yet. Also I imagine the car should be on when I run the test correct? Or only ignition on?
Not really much to test unless you have an oscilloscope. Mainly that the wires are intact and not broken. If you wanted to be thorough you could check the yellow/orange wire at the PCM side as well.
Originally Posted by NickLR5-19
my guess is it must be electrical issue because I’ll try starting and it won’t start for 3 or 4 times and pressure stock at 1.3psi or so, then all of a sudden I try again and I see the pressure quickly climb to the 7psi desired and then it keeps adjusting and matching desired thereafter. Odd.
I think this is important and that you should focus on this first. Since you have a multimeter, measure the battery voltage while the engine is cranking. At rest the voltage should be near 12 volts. When you crank the engine it should not drop below 9 volts or so. While running you'll see 13-14 volts. If you see anything less than 9 volts while cranking then your main battery could be at the end of its life and should be checked and possibly replaced. Most auto parts stores I've been to will do a battery check for free if you can get the truck or the battery to them.
New battery and still an issue. I'm thinking wire loom short somewhere b/w PCM and FPCM. taking to a shop next week because I don't know how to check the wiring well enough. What a pain.
Summarize again where I am: Issue. I start the car on first try in the morning. Then low pressure sensor voltage drops below 1V and low pressure fuel pump PSI drops far below desired and car dies. Sometimes the high pressure sensor voltage also drops.
Then i try starting 3-4 times, eventually it starts, voltages all go back to between 1-4V and fuel pressure matches desired pressures and car will run faultless for as long as i run it.
So far I replaced:
Battery and voltage looks good
High pressure fuel sensor
Fuel pump LR082740
FPCM
Low pressure fuel sensor LR082759
MAY NEED TO REPLACE fuel tube LR 096832 - I have a new one in the box
O2 sensors
PCV Valve
Error:L462 - Discovery 2019
Vehicle scanned on 14-05-2025 13:31
Using IIDTool BT V4.0 B0306-99
PCM-Powertrain Control Module
P025A-13 (AC) Fuel Pump Module, A, Control Circuit Open - circuit open
P008A-84 (AC) Low Pressure Fuel System Pressure - Too Low - signal below allowable range
