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What does open load short circuit to ground mean

I have spark fuel pressure and constant power to the injector

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An "open" breaks a complete circuit - much the way a switch does. When the switch is "on" or "closed" the load should be powered. When the switch is "off" or "opened", power is interrupted and the load is not powered.

A "short circuit" is usually an unintended circuit that is completed without powering the load. Such would be the case if a battery jumper cable were to be crushed so that the copper conductors contacted each other. The amount of current would exceed the amount intended to be safely carried and if allowed to persist long enough - they would burn. A fuse is usually provides the protection in a circuit. If a fuse repeatedly opens or blows, there's a problem. Installing a fuse with a greater amp rating than the circuit is designed to pass is a dangerous fire hazard.

A "short circuit to ground" is where one side of a power source or battery is connected to a common point - in the case of a car, the (-) side of a battery is connected to the frame, chasis, body, etc.. Individual wires are used to pass the (+) voltage and amps to loads. If one of these wires were to be pinched or crushed between parts that are tied to the (-) battery cable, it has "short circuited to ground".

120/240 volt AC systems in homes consist of 3 wires. They are "hot" (black or red wires), "neutral" (white wires) called "grounded conductors" and the "grounding conductors" (bare or green wires). The grounding and grounded neutral are tied together in the meter socket, electric panel or elsewhere and bonded to the street side of the water meter. This makes all the plumbing, boiler, gas pipes, metal electric boxes, etc. to be at the same potential as earth or ground. Touching a hot black or red wire to a neutral white wire will cause a short circuit, and touching a black or red wire to a white neutral OR a bare or green ground wire would be a "short circuit to ground".

I hope this helps :-)

Posted on Apr 16, 2015

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Means the load... injectors?, anything that requires electricity to work, is shorting out to ground, and since it is open, it is not creating a full circuit to the load, so the current is flowing back to ground before the load and the object in question will not work. electrical problems are so much fun..... also constant power to the injectors does not mean they will fire, if you have an open nuetral, or ground you will still see power but there is no way to complete the circuit, you are seeing the power because you are creating a circuit when you test..... i am assuming you are using a dmm or similar..

Posted on Apr 16, 2015

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1994. Why won't it start?

If the fuel pump/s continue to run with key on, suspect a relay issue. The relay is grounded by the vehicles computer. If the computer supplies a constant ground, the relay will continue to stay closed and power the fuel pumps constantly. If the the ground wire that comes from the computer to the relay is shorted/grounded, the relay will stay energized as well. As for the no start, are the injectors getting a power and ground supply? The ground side of the injector is controlled by the computer as well. Is the vehicle getting spark at the coil/plug? Have you scanned the computer for any trouble codes?

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That means bad injectors, or defective fuel pump, you probably need to replace the fuel pump.

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No injector pulse

hello sir,

absence of ground pulse means there is some kind of shorting circuit in your control circuit.

which can make the ground pulse to get shorted there itself preventing it to reach the circuit properly.

thank you

don't forget to rate the solution

good day

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I have a Saab with a service code P0304 I looked into it usually bad ignition coil...I replaced the coil but No go, any ideas?

P0304 code means - Cylinder 4 Misfire detected.

Possible causes are:

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You would put on a new crank sensor because the ignition system won't work, it gives no spark. So now do you have spark at a spark plug wire end? A blue consistent spark? Probably good ignition system, as long as all spark plugs get a spark.

One thing you always want to check with no start is the fuel pressure. Turning the key to on should turn the fuel pump on and put pressure in the fuel rail at the engine. Autozone and maybe others rent or loan fuel pressure gauges. Multi-port injection systems have high pressure specifications, around 40 psi normally. That is what the injectors require to spray out fuel when they pulse and open the nozzles.

With the injector circuit, the first thing to check is if each injector has power to it with the key in ON. One power wire and one ground wire goes to each injector. The power wire is from a fuse that is powered with key on or key in start, and then it is spliced to all of the injectors. The injector grounds all run into the engine computer, where the circuit can be internally grounded for a split second and cause the injector to pulse. But anytime the key is on, the injectors have steady voltage available to them.

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So, it's the injector circuit. There is a 10 amp injector fuse in the fuse block, on left side, 4th one down. Check this fuse. It supplies constant power to both injectors, on the red wire to injector 1, and a white wire splice from this to injector 2. A steady 12 volts anytime key is in on, run, or start. You can check this with a test light or voltmeter. Ground the test light and probe injector connector's red wire on injector 1, and the white wire on injector 2-both should be hot with key on.
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Are you sure it's not the fuel pump? I would be checking fuel pressure-the injectors need fuel under high pressure against them so they will spray out when pulsed.
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There should be a fuse for the injectors, check that. With key on, not start, the injectors would have power to them on the "injector drive circuit". In other words, constant power is supplied to the injectors when the key is on. The other wire at an injector is the ground wire. The ground wire goes into the engine computer. When the computer internally grounds the injector wire for a split second, the injector is energized and fuel is able to spray out.
Post back if you need help checking the injector circuit-both the power side and the ground side. You can check both with a test light.

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I replaced my fuel pump when my 1999 yukon wouldn't start one day. Now still won't start and I replaced the fuel filter. There is pressure but no gas getting to the engine. Don't know w

Guessing when you say pressure that you have fuel pressure and that the fuel pump is working but the injectors aren't pulsing and injecting fuel into the cylinders. The way your fuel system works is that you should have constant power at each injector and the vehicles computer (the ECM) gets readings from different sensors and send a quick ground pulse in order to complete the circuit. each time the ECM sends a ground pulse, that's when the injector injects fuel so the ground signal/pulse is quick (on and off, one and get the idea). The first thing I would do if your fuel pump is pumping and you have fuel pressure is check the fuse. The fuse you want to check should be a 20 amp fuse in the fuse panel under the hood of the vehicle in the engine compartment. Below is a diagram of the fuse layout and I have marked the fuse you need to check (the ECM 1 fuse). If that fuse is blown you will not have that constant power at the injectors. If blown replace and that should solve the problem unless it blows again which would mean you have a short. If it isn't blown make sure you have power at all time when the key is on. The pink wire at each injector should be the power wire. If no power you need to locate the open wire for that circuit (coming from that fuse to each injector). This is where I would start. If you need further instructions as far as any more testing procedures, reply/comment here or feel free to email me directly at Hope it's as simple as a fuse for your sake and I hope this helped.


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