Hi, welcome to Just Answer.
Do you have a voltmeter to check for voltage to the coil Dark Green orange striped wire?
Alright, try switching out the ASD relay in the underhood fuse/relay box, with the A/C relay and see if you get power to the coil...if so, than see if the engine will fire. If not, let me know and we'll test from there.
Alright...could you remove the ASD relay and probe all the terminals for voltage? How many have around 12 volts with the key ON?
Alright, put the relay back in and have some one turn the ignition key on and off, place you finger on the relay, does it feel or do you hear it *click*.
Allright...take a piece of wire and shove it into one of the two terminals that didn't show any voltage in our last test. Place the relay in, and it will further shover the wire and hold it in there. Take your meter and measure for 12 volts on that wire while someone cranks the car. If it has voltage, we're good. If not, remove the relay and place the wire in the last spot and take the reading again.
One of those terminals is the power supply to the coil, injectors, etc. The other is the computer ground signal to the ASD relay. We know the ground signal is good becasue there is 12 volts to the two terminals AND the relay clicks. So once we determine if 12 volts leaves the relay we'll know this is a bad connection between the relay and the components. See the wirng schematic below to follow along, I think our problem lies at Joint Connector #2, which is inside the Power Distribution Box there.
Is this with the relay intalled or with the relay removed? Also is that number 1.99 volts?
Alright, lets do this...can you run a wire from the battery positive to the Dark Green/ Orange wire on the coil and splice it in. Buy one of those fuse holders, and place a 30 amp fuse in the wire so incase there's a short, the fuse will blow. After the wire is in place, see if the engine will run...if so, we know this is definitly the problem and we'll go back to issolating the power supply to the ASD.
That's what I believe, but the ASD circuit and the fuel pump relay circuit do not share any common areas, except they are both signals to the engine computer. Adding power to the coil will also power everything the ASD is supposed to operate, and I've had wiring problems with the ASD before so I think it may be your only problem...but we'll know if the truck runs or not. If it doesn't than the connection problem for the fuel pump relay and ASD relay may be in the PDC box where they're connected into. Below is the schematic for the fuel pump relay. What we'll do is figuer the ASD circuit out and repair it and if this also takes take of the fuel pump relay output - great, if not we'll trace down the fuel pump relay problem too.
Alright, can you pull out the fuel pump relay and check to see how many terminals have voltage, as you did with the ASD relay. Also, on the relay there shoul be the numbers 86, 87, 85 and 30...can you tell me which of these terminals on the ASD relay had the 1.4 volts with the ignition key ON? Was it terminal #30?
Can you check the voltage accross fuse ## (rated 30 amps) in the same PDC box? Check both terminals of the fuse with a voltmeter.
Could you check all the fuses in the PDC and see if any others are reading the same? Also what brand voltmeter are you using? Is it analog or digital?
When you say all the fuses are reading the same you mean that the voltage is fluctuating? Or at 1.4 volts? Also, if you place the meter directly on the battery, what is the reading?
Alright, you should be able to take a measurement with the fuses installed, there are two metal tips at the top of each fuse which you can place your meter probe on, while the fuse is inserted. See if the reading is 12.30-12.45 volts, if it is, than measure the ASD relay terminal 30 one more time and see if it's 12.30-12.45 volts...if not - we have a break in the wiring under the PDC box; and this may be what's affecting the fuel pump operation as well.
No, the ASD is simply a relay which protects the circuit. The ASD circuit includes the fuel injectors, ignition coil, and some sensors...the fuel pump is on it's own circuit because it's a higher amperage motor. The only two common areas both of these circuits share is the computer itself and the power supply from the battery to the PDC box.
We need to eliminate the idea that there is a "reset" of any type on the truck for anything...the only reset there truly is, is the computer through a scan tool or battery disconnect for resetting the idle and fuel trim values. If we are loosing power to one of the ASD terminals there is a hard wiring or connection problem under the PDC box that may also be interfering with the fuel pump relay as well. Electrical problems like this can even be a nightmare for a experienced automotive electrician, but that's also why they would charge anywhere from 2.0-8.0 hours to rectify this.
I think we're close to a solution, if you were measuring the voltage with the fuse removed before, we weren't getting a correct reading. So with the fuse installed if we have around 12 volts on each side, yet only 1.4 volts on the #30 ASD terminal...you need to unbolt the PDC and look under neath at the wiring connections. It's a mess of wires under there and can become very confusing...so we need to take our time and figure out why the connection between the fuse and the ASD #30 terminal has that voltage drop. At the same instance we can test the wiring under the fuel pump relay as well. It seems as though if we power the fuel pump separately and the ASD Dark Green/Orange wire...the truck should run. I had a similar problem a few months back on a 1500 Dodge truck and low and behold it was a bad connection at the fuse under the PDC box...but this customer didn't have the fuel pump issue.
With the fuel pump relay removed, jumper terminals 87 and 30 with a piece of wire. turn the key on, can you hear the fuel pump running? Should use a 10 guage wire, there's a lot of current through this circuit.
Sounds like there's a bad connection at the computer harness or disturbing it there, caused a connection at the PDC. How about if you now remove the ASD and jumper it between the #30 and #87 terminals, will the fuel pump run and the engine fire becuase we have power to the coil and fuel pump pressure?
While the engine runs (if it does) wiggle the wiring at the computer and see if the engine dies.
So keep the computer plugged in...jumper the ASD and the Fuel pump relay both...does it run than?
It may be that the battery is getting weak now, do you have a charger that you can place it on? A weak battery can cause these type of electrical changes. We need to know before digging further into it.
Alright, after the battery charges, be sure the negative cable is tight and follow the negative cable to the battery and be sure it is not corroded or loos on the body or block...ground problems can also cause various electrical faults. After the battery charge and ground check, keep the ignition key on and wiggle the computer wire harness and the harness going into the PDC, listen for the relays to start clicking indicating the wiggling of the harness is causing the wires to make contact somewhere.
I'll be offline for a couple of hours, so let me know the results when you can.
Well it does sound like the computer is playing a large role in this problem, and it may very well be the root cause. But I personally haven't had the computer cause the ASD and the fuel pump relay to not trigger. Do you have access to a code reader to check for diagnostic codes? Is the check engine lamp still comming on when you turn the ignition key on?
What voltage were the wires going into the PDC reading? And can you describe those wire colors?
This is the computer your disconnecting - correct?