Fuel pump not getting signal from PCM

OK, SO ENGINE IS DEAD, CRANKS BUT IS DEAD
AND now doing pump tests wrong. (as most do)
the relay has 4 pins.
to test the relay you must crank the dead engine.
and all fuses good first.
do not try to test the relay for the short prime pulse or go slowly mad. (2 man job and slow meter you will fail)
prime pulse 1second long, some even disable prime too cold outside, so I never trust the prime.
crank the engine.
2 man crank the dead engine (my guess what's up)
the contractor in the relay 2 pins ,one pin is 12vdc full time key on and 2nd one goes to 12vdc when relay energizes. (and pump gets 12vdc to it cranking.
the RELAY coil does that. in the relay.
the RELAy coil has 2 pins, 1 on this truck 4.3 is grounded hard, other coil is PCM
and is 12vdc from PCM, to coil 0v coil is dead.

that is how it works and how to test it correctly
learn the PCM cuts fuel 4 or more ways,


the facts are (have schematic up now)real.
ECM fuse B not blown or FP relay be dead.
PCM C2 pin 9 runs the relay coil
fuel pump not dead or its ground rusty.G402
Ok other coil pin on relay is grounded G102.
so he PCM sends 12vdc to the relay C2-B7
if not the relay will be dead.

fuse B is hot all the time so super easy to check
12vdc both ends of fuse is good for sure cranking
all fuses to PCM must be good.
battery voltage cranking is near 11v below 10v bad things happen.

if you scan the PCM it may tell you why it fails
why not scan any modern car first?

best on any dead engine, (but cranks fast)
all fuses good
scan it cranking
the check spark first not fuel fuel first
cant burn gasoline, with no spark.
the PCM(ecu) cuts fuel injectors if spark is detected by PCM bad.
the PCM cuts spark and fuel if crash SRS sensors tripped.
the PCM cuts fuel for other reasons even tps bad.
The pump is last. to test./ on any dead EFI engine
and do so cranking.
use a voltmeter to find it.
the pump is bad if 11vdc makes it to pump actual
cranking, and rail is 0psi.
if the FPR fails 2 ways stock closed PSI is 2 times normal and floods, engine if FPR is stuck open
PSI is 1/2 normal or less and engine dead or starves for fuel, weak engine and or idles a bit and stalls
see why I asked whats up? no told./
the real deal
my generic schemo. but is true.

Power flows from the fuse to the fuel pump relay. The control coil in the fuel pump relay gets ground from the PCM. If the PCM doesn't provide ground, the relay contacts won't close and you won't get power to the pump. The PCM won't provide ground if it doesn't see a good circuit from the remote keyless entry module. That's a common failure point. Pull the fuel pump relay and check for ground from the PCM when turning the key to start. If no ground, troubleshoot the RKE module

A bad fuel pump relay ! The PCM not turning on the relay , a open wiring circuit to the fuel pump !A blown PCM/BAT fuse in the IP fuse box ! Do you know what a relay is ? Is the SECURITY light on the dash ?

The line is continuity... it completes the ground signal back to the pcm. Then the fan is turned on. Problem most likely, connector needs replaces going to sensor... common problem. Be watchful when placing new connector on once you have spliced the new one on, since there is only one way that it fits in and might cause damage if forced in the wrong way.

gotta start with the color code of the wiring. verify that is correct first. you have to have fuel pressure for it to run obviously so make sure you wired it correctly. Here is the color code according to Mitchell OnDemand
black/orange= ground for fuel pump
orange/red=power on for fuel pump(only gets triggered from fuel pump relay)
dark blue/white= signal to pcm for fuel level
dark blue/ dark green= ref voltage

If that is ok then check for relay activation. Fuse 17 is the power source for that relay. If you have a good fuse but no relay activation you could throw a relay at it but if that doesnt do it then its gotta go to a shop. But if you are curious....
Relay code
pin 30= hot at all times
pin 86= relay control trigger from the pcm
pin 85= hot in run or start
pin 87= power source to fuel pump.(i.e. orange/red wire)

the relay will have numbers on it designating the correct pins. Get that right first then move on to the next. I'll be here. Good luck!

The fuel pump fuse gets its power from the fuel pump relay, which is located in the Instrument Panel Junction Block.

The fuel pump relay gets its ground from G102, which is located just forward of the left strut tower.

The fuel pump relay gets its power from the Powertrain Control Module Connector "C" Pin 10 ( DARK GREEN/ WHITE wire) for the primary side of the relay.

The sencondary side (the side that provides power to the fuel pump fuse) of the fuel pump relay gets its power from the IP BATT Fuse (30 Amp) HOT AT ALL TIMES in the underhood fuse block.

This should be enough information to figure out why your fuel pump is not getting power. Let me know what you find.

You have 2. 1 At the under hood fuse panel, which is the 3rd one up on the right side (30a IP Batt). Then you have 1 inside kick panel on left side of passenger side. It is a 10a and is called body...above fuel pump relay.

Hello! The fuel pump relay is located on the bottom right of the instrument panel junction block...the junction block is beneath the center of the instrument panel...

Guru.............Saailer


I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

could be relay,,,that's on the passengers side fire wall,,

I would have to check the fuel pump with a scope to look at the pattern and check the amps it is drawing . the grounds need to be checked and the pcm checked and reflashed. on the fuel system that would affect the fuel pump and relay to where it would burn it out is grounds , pcm , fuel pump , fuel pump relay. so you should convince them to replace the fuel pump and fuel pump relay under warranty and replace the pcm . and get a diagram and check all grounds. If the pcm is damaged and the current has been affected and instead of say a 5 volt or 2 volt signal it now has a 13.5 volt signal or if a ground is out then the temp of the relay will keep rising non energized a relay is about 99 energized it is around 140 you can check to see how hot that relay is getting. and if i remember correctly you want the pcm drivers checked.