2005 Chev Astro 4.3 L - Green and white wire going to activate the fuel pump relay is not getting hot with key on or crank. no fuel pump working

I don't know liter size of engine? The relay has two sides, the load side and the control side. The load side, looks like open switch, left side. Terminal 87 is hot all the time. The right side of relay is control side, needs voltage and ground. On the control side, dark green wire with white tracer is voltage, comes from pcm. The black wire is chassis ground.
Are you missing anything else? Engine cranking, you have spark at the plugs where applicable, and fuel injector pulse? With engine cranking, if your missing everything, I'd have to check rpm signal.

For initial prime, you have to check fuel pump relay and wiring circuits. The control/coil side of relay gets voltage from pcm, green wire with white tracer. The ground for control side of relay, should be a chassis ground. Voltage for load side of relay is fuse protected.
This vehicle has an oil pressure switch in fuel pump circuit, just a redundant power supply to the fuel pump. Even w/o the relay the vehicle should start and run, once the oil pressure builds up and that switch closes, the fuel pump will get voltage. There won't be any initial prime w/o the relay.

On the pump harness, the pink wire goes to the sending unit and the gray or tan/white goes to the pump.
On the relay, the green/white grounds the relay from the engine computer, the orange is hot, the red is a jumper wire, and the gray goes to the pump. Keep in mind the relay is only "on" for 3 seconds when you turn the key on. The engine computer must see RPM or oil pressure to continue to power the pump relay.

The clicking noise at the relay indicates that the relay is bad, or that the wires to the relay and/or connector is bad.

A relay is an electronically activated switch. Inside is a coil. When 12v+ is applied to one end of the coil, and a ground is applied to the other end, the coil gets charged, creating a magnetic field. This magnetic field literally moves a metal lever from position A to position B. One end of the lever is attached to constant battery power. When coil not energized, the lever rests in postion A (which in the case of the fuel pump relay is feeding the battery power to an unused terminal). When the coil is activated, the lever moves to position B (which in this case is a terminal connected to your fuel pump wire). Thus, when the relay is activated, 12v+ is being directed from the battery to the fuel pump.

This fast clicking indicates that the relay coil is not getting a constant voltage or ground supplied to it, thus the lever is moving back and forth between position A and position B, either there is a wiring issue, a connector issue, or an internal issue with the relay.
The relay has 4 wires, black, grey, orange, green with white stripe.
black = ground
orange = battery = 12v+ always
grey = wire out to fuel pump (on some cars this wire is tan with white stripe)
green/white = signal wire from ECM

When key is turned ON, the ECM sends 12v+ out on the green/white wire to the relay for about 2 seconds - this activates the relay coil for 2 seconds, thus running the pump for 2 seconds (priming). When the vehicle is started, the ECM sees a constant ignition signal from the ignition module, and sends a constant 12v+ out on the green/white wire, thus activating the relay coil constantly, and thus running the pump constantly.
When car shut off, no more constant ignition signal, thus ECM stops sending the 12v+ out on the green/white wire.
So, you can kind of test your connector ...
1) remove connector from relay
2) jumper a wire from the slot for the orange wire to the slot for the grey wire - fuel pump should run - wiggle wires to verify at connector
3) probe black wire slot with ohm meter - make sure black wire has constant ground - wiggle wires at connector
test relay ...
1) remove relay from connector
2) rig a ground wire to the tab that had the black wire when in connector
3) apply 12v+ to the tab that had the green/white wire - relay should click once and do this every time you apply the 12v+

That should help you track it down to either a connector problem, a wiring problem, or a relay problem.

Make sure you're getting power to the fuel pump after start up. GM cars provide power to the electric fuel pump via the starting circuit when cranking and switch to alternator/battery power via the fuse block and 12v relay with ignition on in run position. Check your fuse block (bad fuse; power not getting to part of fuse block) and fuel pump relay. Could also be plugged fuel filter, bad pump or ?. but not likely because you get fuel while cranking. Check for error codes in the engine control computer (GM OBDII) as well but that probably won't show anything. Good luck and good hunting. I had a similar problem with a Chev Astro. Turned out to be power not getting to one bank of the fuse block because of a burned junction terminal buried behind the battery under the hood. Get out the multimeter and start looking for failed electrical components or broken wires.

WHAT ENGINE ?????? 4, 5.2 or 5.9 Liters?
Fuses are First, always for ever. on electrics or EFI.
dry rail cranking ! you must crank it.
(if you have liking injector or leaking regulator it can drop fast ,so crank on) yes, 2 men or 1 and small boy, LOL
so check voltage at the pump cranking. please stop guessing.!

the ECU commands up the PUMP , cranking or running
so crank and read voltages at pump or at FP relay.

pump activating, is by premissives. not just a key on event
due to crash and burn rules. (unlike on TV)
same with injection. (spark must be good)
first , buy your self a voltmeter (DMM/DVM) its a very easy tool to use
and on volts, mode, totally harmless to you or car. !!!

be aware, that on some cars
if there is no spark, there is no fuel pumping
or it might take a second to detect no spark and the pump is cut
or on one of my cars the pump works the engine starts for 1second
and the ECU sees no spark (dead tachometer ) even though spark is
good the ECU sees no spark and ALL fuel is cut, injectors and fuel pump relay ( you never monitored the action of the relay?. and its dead.? i bet?) spark monitoring can fail with good spark, !!!
the path, on all cars.............. pins and colors change to confuse...
-------------------------------------------------------------------------
the FUEL pump relay is in the PDC
it has 4 pins, its just a 4 pin std, relay.
a coil and a contactor
if the coil is not HOT (12v across the coil) cranking
there will never ever be pump action.
so the first test is to check the PUMP relay coil wires.
the coil hot side is 12vdc key on
the other wire, marked. C20 DB (dark blue?)
it is 12v keyon
and when you crank the PCM grounds this wire and it must go
to 0v, (0.5v max) if not the PCM is in CUT FUEL MODE.
99.999999% sure, its not a bad PCM. see?
if this line dont go low you must find out why the PCM is in cut fuel.
this is pretty easy,its called a scan tool. got one
they only cost $9 (ask)
if the coil is hot at C18 relay pin and 0v at C20
this state the Relay is energized.
so we check pins C16 and 17,of said relay
we check C16 first. its 12v even key off, hot at all times if not, the fuse is blown. (or battery totally dead)
then crank and pin C17 goes hot(note my order of testing, its not random) C17 dead, is bad relay, C17 12v, cranking is dead pump.

C17 is DG/wht wire, (darkgreen.with white stripe?)
if this wire is cut the pump is dead
so is the pump dead, if hot this wire is, and the pump ground wire is cut.
when i say cut that means cut or corrosion,etc.
eg; gross resistance in the path.

takes 4min to show, and longer to type this...
the G305 pump ground black must not be bad. (12v on black wire is just that while cranking)

i will not fully cover PCM permissive on the pump.
but will do so in short.
1: ECU sees spark loss, for any reason.. even when good real.
All ECu do this differently. many read the spark coil primary
wires of inductive (EMF) kickback , on one or all coils.
other cars its just the tachometer signal dead.
2: CMP errors (cam sensor)
3: CKP errors. (crank sensor)
4: TPS stuck at WOT , usually only cuts injectors.. (unflood mode)


ive built and programmed PCMs from scratch and am aware of all pitfalls here. am.
if have the drawings, ask.
or log in to Alldata.com

again, connect the $9 scan tool
keyon
crank for 5 seconds. (min) max 15)
does RPM roll from 0 to near 300? no? bingo.
does DTC 340 or 350 store as you crank or release key
and do not turn off key, wait 1 second, see if DTCs are stored
in the PCM looking with any scan tool made..
if yes, BINGO !!!!

When you first turn on the key, no crank, the fuel pump should run for a few seconds then stop. There shows to be an oil pressure switch in parallel with the fuel pump relay. It's just a redundant power supply to the fuel pump. Once it cranks enough to bring up oil pressure and the switch closes, the pump will run even w/o the relay. Both the fuel pump relay and oil pressure switch get voltage from the ecm b fuse.
At the fuel pump connector, check voltage and ground, when problem is ongoing. Gray wire is voltage--black wire is ground.
You could pull the fuel pump relay, use jumper wire between terminals on load side of relay. The load side is that line with arrow head, when energized that line moves to the other terminal. As you can see, the orange wire is hot all the time, the gray wire carries voltage to fuel pump. If it runs with jumper, then check control side of relay, the control side has to have voltage and ground, dark green wire with white tracer is voltage comes from pcm. The black wire is ground.

won't claim as a solution but...

Have you verified that fuel is pupming (is the fuel pump working?)

there is a pressure regulator on the end of the fuel rail that is vaccuum activated.... is thier vaccuum getting to it to create pressure for the injectors..

Just s few items to check....

the fuel pump relay is on passenger side front fender second one from the left facing engine. THERE IS 4 WIRES COMING FROM IT, Orange, dark green with a white stripe, Black with a white stripe and gray. the fuse is on the inside fuse box it is listed as ECM-B FUSE.

There is no fuel reset button on this van.

To test the circuit before removing the tank, you will need a voltmeter or cheap test light. Disconnect the connector at the fuel tank. On the harness side, locate the gray wire (fuel pump wire). Connect the test light to a good ground. Have a helper crank the engine over. While engine is cranking, the gray wire should have power. If it does, and the pump is not turning on, then the pump must be bad and need replacing. If there is no power on the gray wire with engine cranking, the circuit is the problem, not the pump. Go back and find the fuel pump fuse in the junction block (the fuse relay block where the fuel pump relay is). Check the fuse, also check if there is power going to the fuse. This fuse should be hot at all times. The circuit goes from battery to pump fuse to fuel pump relay to gas tank and the fuel pump.