Injectors have no pulse, not getting power to injectors?

Hi,

If you have no power to the injectors on one side of the engine, have you checked the fuses? Each side or engine bank has a separate fuse for the fuel injectors.

Take a look below. Note there are injector 1 and injector 2 fuses. I need you to check both fuses and confirm there is power to and from the fuses.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Also, pic 2 shows the under-hood fuse box. I highlighted the fuses to check.

Let me know what you find.

Take care,

joe

See pics below.

Fuse number two was blown, I put a new fuse on it and restarted the truck, it still has no power to the injectors. I haven’t put a test light on it yet. But the fuse did not blow.

Hi,

Okay, if the fuse was bad, something is happening. When you check any of the injectors on the engine, do any of the pink wires have power to the bank in question? Also, check to make sure there is power to and from the fuse you replaced.

Let me know what you find.

Joe

I put another fuse in, turned the power on, and it blew the fuse. When I pulled the fuse and checked the connections, the left side has no power. I’ve searched for the grounds that I could find and clean them and reinstall them. The only ground that I haven’t got to is the one on the driver side door rail under the dash. But I am really stressed out because it’s my only vehicle, and I work from paycheck to paycheck and it’s costing me a fortune. And I don’t know how to check the lines on the injectors. At least not with the test glad that I have which is included.

Hi,

If the fuse failed as you mentioned, disconnect each of the injectors and see if the fuse still fails. If it does, then we have a short between the fuse and injectors. If it doesn't fail, then connect one injector at a time to see which one causes it to fail.

Once that is determined, check the connector as well as the wiring to that injector. If it is good, we need to replace the injector.

Let me know. Also, the test light you have is perfect. It will do the job if we need to go that route.

Take care and let me know what you find.

Joe

I pulled all the connections to the injectors, plugged a new fuse in, turned the key on, and checked the fuse. It’s still blowing without connecting any of the injectors. And it’s still the only fuse that blew.

Hi,

If the fuse failed with the injectors disconnected, then we know it isn't a shorted injector. That means the short is in the wiring to the injectors. Are you able to trace the wiring from the injectors back to the fuse box? Also, are all connectors in good condition?

Let me know.

Joe

All the connectors seem to be in good shape. But I don't know how to test the connections without blowing the fuse again. I looked under the fuse box and the wires are all connected and in good shape. But I don't know how to find the wire from the fuse to the ignition. Because when I turn the key, it blows the fuse.

Hi,

What to do is this. Disconnect the battery and check the power supply wire on each injector for continuity to ground. Pick a place on the engine or body that will provide a good ground for you. If there is a short in a wire to ground, it will have continuity. If there is no short, the circuit will remain open.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-wiring

Let me know what you find.

Joe

Oh, the friend of mine, and I checked the wiring harness for brakes, and there were none. We also pulled the plugs on the PCM unit and checked the wiring there, there were no brakes there either. It was still blowing fuses at that point. So, we put a 25-amp fuse in it to see if the injectors would fire and everything seemed to work okay at first. I drove it around the block, but the engine light came back on, and it started misfiring. I got it to a parts store and had it scanned. It gave me a P0 300 code. I got it back to the house checked all the injector plugs to make sure they were all plugged in all the way, and then I put a new 15-amp fuse in it and it didn’t blow when I turn the key on. I did this a couple of times to make sure. But the fuse still did not blow. I’m not sure what happened. I checked it with the test light, and both sides are lighting up whereas before only the right side of the fuse lit up. my friend thinks that the PCM might be bad. I’m going to test drive it around the block tomorrow because I have to work tonight and see how bad it still misfiring.

Hi,

Thanks for the update. And yes, that is a very good possibility. Be careful when you change fuses like that. It can cause more damage to something or even cause a fire.

If you have a chance, let me know what you find tomorrow. Also, clear the code and see if it comes back.

Take care,

Joe

Can I clear the code by disconnecting my battery? I have seen this done before but I wanted to make sure that it was okay to do so.

Can you also please send me a link to get a wiring diagram that I don’t have to pay for? I would really appreciate that if you can.

Hi,

As far as disconnecting the battery, it may work. Normally, it is based on the code type. As far as the wiring schematics are concerned, I don't have a "free site" to offer. I have access to most all of them so if you need a specific circuit, you can ask me, and I can get them for you for free.

Let me know.

Joe

Can you please send me a wiring diagram for the PCM to the right-side injectors? I think it’s #1 injector bank, #2 fuse. Then can you tell me how to test it with a multimeter? Thank you so much for your help with this.

Hi,

I would be happy to. If you look below, I attached the schematic and highlighted all the signal ground wires from the injectors to the PCM.

Note that each injector has a pink wire. That is the power supply. It should have 12v with the key in the run position or start position.

Here is a link that you may find helpful when testing wiring:

https://www.2carpros.com/articles/how-to-check-wiring

If you are testing for a signal ground, it is easier with a test lamp. Connect the test lamp alligator clip to the battery-positive terminal. Probe the ground wire with the test lamp. Have a helper crank the engine. If the ground is working, the test lamp will strobe on and off.

Let me know if that helps.

Take care,

joe

See pics below.

I got a new PCM for the truck. But it won’t start until I can get it through the passkey system so I’m clearing the codes by disconnecting the battery cables and then connecting them with a jumper cable to get rid of the residual charge in the PCM battery. And then try doing the three, 10-minute cycles to reset the pass key code. But it drains my battery so quickly, and my battery charger is only a four-amp charger, that I can’t maintain a 12 V charge in the battery while doing that process do you have any suggestions other than taking it to a mechanic to have it done?

Hi,

Your battery shouldn't drain that fast. Are you sure it is good? Also, could there be a heavy drain on the battery?

Let me know.

Joe

I got the engine to run well, but I got a p0641 code. So, I need to know what sensors are connected with the 1 circuit.

And maybe you can tell me what to look for?

Hi,

The code is unique. The PCM provides a 5v reference to the oil pressure switch and the MAP sensor (manifold absolute pressure sensor). These 5-volt reference circuits are independent of each other outside of the PCM but are bussed together inside the PCM. Therefore, a circuit condition on one sensor's 5-volt reference circuit may affect the other sensor's 5-volt reference circuits. The PCM monitors the voltage on the 5-volt reference circuit. If the PCM detects that the voltage is out of tolerance, DTC P0641 sets.

Start with the oil pressure switch. Disconnect it and check for power. If you have a digital multimeter, you should see 5v with the key on. You can do the same with the MAP sensor

Let me know the results.

Joe

I did as you suggested and checked the map sensor plug as well as the oil pressure sensor plug for power. Both carry 5 V. When I disconnected the oil pressure sensor, my engine light turned off. And the truck runs just fine. When I plug it in, the engine light comes back on and the oil pressure gauge shoots to 80 pounds. When I jiggled the wire, the oil pressure gauge went back down to zero and the truck ran fine. So, I ordered a new pressure sensor for it and that should take care of the problem. I appreciate all your help Joe. You’ve been very patient with me in this.

I would also like to ask you about how to wire the new throttle body that I have. The old one still works fine, but it probably needs a new one, but I need a wire diagram for the plug because apparently the new sensors are wired somehow differently. If I need to, I can take a picture of the sensor and the throttle body unit and send it to you so that you might have a better idea of how I can wire it.

Hi,

Thank you for the update. I'm glad to know you found the issue. Make sure the connector or wiring to the sensor isn't the issue.

As far as the throttle body, if it isn't causing problems, I would leave it alone. If you have a new one and the sensors are different, that can lead to new and more difficult issues to resolve.

Let me know if the new part takes care of the problems.

Take care,

Joe

Oil after changing out the oil, pressure sensor, the engine light went off for about four days, and then it came back on, and told me that both of my field banks are running rich. And so, I changed out the air filter because it was very black and very old. Hoping that this will solve that problem. But my question is, would it be the new injectors that I installed? Because they are four hall injectors, rather than the original two whole injectors, which I still have. They seem to be very clean.

Hi,

If the fuel pressure is within specification, then I would suggest reinstalling the original ones to see if the problem goes away. There is a good chance that is the cause.

Let me know.

Joe

I put the original injectors in, and so far the light has not come on. But it took a couple of days for it to do that before, so I’m going to wait for another day and see what happens. Meanwhile, I’m going to clean out the mass airflow sensor Because I bought some mass airflow sensor cleaner. I figured it would be a good idea and it might help a little more.

Hi,

Thanks for the update. Hopefully, that will take care of the issue.

If you plan to clean the MAF, here is a link you may find helpful:

https://www.2carpros.com/articles/mass-air-flow-service

Let me know how things turn out for you. I'm interested in knowing.

Take care,

Joe