readymix
3/4 ton status
If you have +12Vdc to one side of your injectors "481(red) and 482(white)" then you must have a broken wire or a bad ECM....unless both injectors are faulty
CK5
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So you have power to the 12V input TO the ecm from battery power right? Its not very likely that the ECM has failed both the grounding circuit AND the power supply leg output TO the injectors too.
If you've got no power AT the injectors, you can simply supply that with a jumper or something right from the battery if you wanted. That will for sure tell you if the power or switched ground is missing.
You need to get as close to the ECM pin terminals for the power and ground feeds to the injector and test with a noid light if possible during cranking. If that harness has a poor connection, it could be the answer (more often it is than having an ECM failure or component failure).
What's also troubling though is this comment about the fuel pump relay not activating. If that's true, it would almost seem like your ECM might have bad power and ground connection because both of those circuits failing internally in the ECM would seem to be very unlikely.
Just to be clear, where is the ground for the ECM?
Unfortunately, I don't have a pinout for the ECM connector, or a wire diagram so I can't help much there.
Are we talking about the ECM's ground itself, or the ground path that your each injector gets from the ECM connector?
If you can pinpoint that pin terminal location - I'd highly recommend that you jumper a direct path to ground right from the battery or something in order to ensure yourself with no doubt that the ECM has a good ground. In a situation like this, a nice set of jumper wires is indispensable.
I guess what I am trying to say is that you want to try to minimize the use of any of the wires that exist in your current harness that are involved in making the injectors pulse. In the end, it isn't that tough to do, and there's no real cost involved. ECM replacement on the other hand becomes VERY expensive.
Still a little confused about that fuel pump relay comment though...
Are we talking about the ECM's ground itself, or the ground path that your each injector gets from the ECM connector?
If you can pinpoint that pin terminal location - I'd highly recommend that you jumper a direct path to ground right from the battery or something in order to ensure yourself with no doubt that the ECM has a good ground. In a situation like this, a nice set of jumper wires is indispensable.
I guess what I am trying to say is that you want to try to minimize the use of any of the wires that exist in your current harness that are involved in making the injectors pulse. In the end, it isn't that tough to do, and there's no real cost involved. ECM replacement on the other hand becomes VERY expensive.
Still a little confused about that fuel pump relay comment though...
readymix
3/4 ton status
Injector one (wire BLU 467) goes to the ECM on pin D16
Injector two (wire GRN 468) goes to the ECM on pin D14
Injector two (wire GRN 468) goes to the ECM on pin D14
ChadRay13
1/2 ton status
Find the power wire at the ECM and run a jumper to it.
In the case of jumping the injector. It's a good idea, just unplug it from the ecu first to prevent back feeding the electric current.
In the case of jumping the injector. It's a good idea, just unplug it from the ecu first to prevent back feeding the electric current.
Ok, so I bypass the and wire the ECM live to the battery with a jumper. It starts
So, what the heck am I missing?
readymix
3/4 ton status
What wire did you jumper exactly. There may be a break in the wire or a fuseable link
c16
ChadRay13
1/2 ton status
So it starts and runs when you apply an outside power source(jump wire)? This tells us that some where along that wires travels is a break. It could be something from the wire is snapped/broken or the pins for the fuse/relay is not making connection. What you need to do is get a test light. See if it lights up at c16 at the ECM. If/when it doesn't. Follow it to the next item in the circuit. Test the wire. If it lights up the the break is between that spot and the ECM. If it does not light up follow to the next spot in the circuit. Checking for light.
I suggest a multimeter because some lights will come on with low voltage but not enough to power the component. A multimeter will let you know you have B+.
I suggest a multimeter because some lights will come on with low voltage but not enough to power the component. A multimeter will let you know you have B+.
Ok, I have power to the fuse block.
readymix
3/4 ton status
C16 on the ECM is circuit 440. That comes from the ECM-B fuse.
I have already check the fuse with a multi meter, but will check where the fuse goes in. I have power to the firewall side of the fuse block.
readymix
3/4 ton status
Circuit 440 goes to a few different places you could check for power. They all come from the ECM-B fuse
1. 440A goes to the fuel pump relay (1.0mm orange wire)
2. 440B goes to the ECM on C16 (1.0mm orange wire)
3. 440C goes to the ECM on B1 (0.8mm orange wire)
4. 440D goes to the engine connector on pin "Z" (1.0mm orange wire)
5. 440E goes to the oil pressure switch (1.0mm orange wire)
1. 440A goes to the fuel pump relay (1.0mm orange wire)
2. 440B goes to the ECM on C16 (1.0mm orange wire)
3. 440C goes to the ECM on B1 (0.8mm orange wire)
4. 440D goes to the engine connector on pin "Z" (1.0mm orange wire)
5. 440E goes to the oil pressure switch (1.0mm orange wire)
readymix
3/4 ton status
I'll be outside mowing the lawn, but I'll check in on this thread when I get time to see if you need anything else form the Helm manual.
It looks like we are on the right track though.
It looks like we are on the right track though.
I have found that meters can show 12v regardless if there is enough amperage to power the item in question. A test light will be dim or not light if the voltage supply is weak. I always use a test light for quick power supply testing because of this. Light it up on direct battery voltage when you start so you know how bright it should light up.
ChadRay13
1/2 ton status
Amperage stays consistent in a circuit. 0v-12v the Amperage should always remain. That is why you check ALT out put on the negative battery terminal. Amperage will how ever decrease within a circuit the more resistance that is in a circuit. So I can understand If there is an added resistance factor some where in the circuit there being less than sufficient amps. But you will see a voltage drop at the component in which you are trying to power.
A multi-meter is always far more accurate of a diagnostics tool than a test light. Assuming you have more than the $2 one from HF. A test light takes very little actual amperage to light up. In terms of electrical components and sensors 1v can make or break the computer from reading things correctly. Such as an oxygen sensor that uses 1v reference voltage. and .92v is ideal output to ECM.
The ECM how ever should take very little amperage compared to say an electric fan.
I don't mean to come of rude or arrogant in any way.
Edit: I am waiting for Fordum to pipe in, correct me about something and get way more technical. lol
A multi-meter is always far more accurate of a diagnostics tool than a test light. Assuming you have more than the $2 one from HF. A test light takes very little actual amperage to light up. In terms of electrical components and sensors 1v can make or break the computer from reading things correctly. Such as an oxygen sensor that uses 1v reference voltage. and .92v is ideal output to ECM.
The ECM how ever should take very little amperage compared to say an electric fan.
I don't mean to come of rude or arrogant in any way.
Edit: I am waiting for Fordum to pipe in, correct me about something and get way more technical. lol
You guys are probably right. I have a nice Fluke meter but it's "old". Bought it in 1995 "old". I just remember chasing my tail diagnosing a power seat problem. All the grounds were good, power supply showed 12v. Could jumper power to the motor and it would work. Older tech in the next bay says "try it with a test light" and sure enough it was really dim. Ended up poking the wire till it was bright. Found a corroded connection under the carpet. Bought a test light after that. 
So, that situation always pops up in my mind when I look for power supply problems. These new fangled LED test lights probably light up at the drop of a hat. My old light bulb style test light can and will vary it's brightness depending on its supply V strength or ground depending on what I am testing.
So, that situation always pops up in my mind when I look for power supply problems. These new fangled LED test lights probably light up at the drop of a hat. My old light bulb style test light can and will vary it's brightness depending on its supply V strength or ground depending on what I am testing.
