I have a solid check engine light with key on engine off, the fuel pump won't prime, and my car won't start

I did the Honda k test and usually if it's low volts the Ecu is bad, but mine reads 12 volts on all wires instead of 5! Someone please help I don't have another car I'm going to get fired if I don't get this car going ASAP!

Are you sure you performed the K-Test properly. If the CEL stays on, when the ignition switch is turned to ON (Position II), then the odds are that the ECM has failed. I would install a remanufactured ECM (exact Honda Part No. match), shopping for price and warranty.

There you are, I did start my own thread I just didn't know how this site works. Im pretty sure I did the test right, all I need to do is unplug map sensor, turn ignition to on position, and I put the ground lead on the ECM ground on thermostat housing, and the other lead on the connector. I did all 3 wires and most people either find very low voltage, or they find 0v 4.5v and 5v.. But I see battery voltage on all of them. I also was able to find info on main relay harness testing and it seems all wires from relay to Ecu are OK. I did swap out the main relay for a known good one, and nothing. I also swapped the ecu, but no luck, maybe both ecus are bad?

Is that right or did I mess up? I'm so confused. I can't find any information on the I test showing battery voltage..

Be sure to test all under dash and under hood fuses with a test light or multimeter. Be very thorough. Especially check the ACG (ALT) (S) fuse in the under dash fuse box. Also, check the ignition switch for wear, pitting, or melting.

It's important to ensure that you have installed the correct ECM. As the inventor of the K-Test, I've never seen 12 volts! Reference voltage should always be 5 volts.

Any ideas? Thanks so much for taking the time to help me! I've been reading all your replies to similar issues, but I noticed a difference. None of the other people read battery voltage while doing the k test so that just confuses me. And I don't have acces to Ecu or engine harness wiring diagrams.

Sorry I posted that last one before I saw your reply. I did test all fuses and all seem OK BUT there is one that melted... The Ecu fuse is in the corner towards the left and that one is OK, but then all the way to the right towards the firewall, the one in the corner is melted. Looking at a diagram it says that one is for rear window defrost. Once again, I don't have diagrams, so there's no way for me to see if that circuit is directly or indirectly related to the Ecu and main relay or my issue in general

I would remove and clean the main ECM ground, located on the thermostat housing.

The problem is with the ACG (ALT) (S) fuse, in the under dash fuse/relay box; ECM (perform the K-Test); main relay; or the ignition switch. Perform tests in that order.

The ACG (ALT) (S) fuse is in the under dash fuse box, not the under hood fuse box. It's close to the SRS fuses in the upper right hand corner of the fuse box.

I checked that fuse, and it has power (battery voltage) going to it. So if there is voltage and the fuse is good now what? I used a fluke multimeter to check and verify the voltage.

The ECM fuse is good under the hood. I have battery voltage going through it key off engine off like its supposed to. The ACG ALT S fuse has battery voltage only on key on engine off. I swapped the main relay with a known good one, I literally just installed a 3rd Ecu that I know for a fact is in good working order, and as for the I test, I did it again, and it's still reading 12 volts.. But I think I may have done it wrong or it's all grounded out... See, I put one lead on the power side of the battery, and the other one on the power to the map sensor and I get 12 volts. Same for the other 2 wires.. Shouldn't it be the other way around? Shouldn't I have to put one lead on ground, and the other one on the wires? If so, I'm getting really low voltage, but once again, I've installed 3 ecus already..

Yes, you performed the K-Test incorrectly. Here's how it should be done:

The K-Test: Remove the MAP Sensor connector and turn the ignition switch to ON (Position II). Using a multi-meter, check for 5 volts going between the MAP Sensor connector's reference wire (+) and ground. As you look at the connector, this is the socket on the right. Really press the black test lead into a cleaned main ECM ground on the thermostat housing. If the voltage is low, it’s probably indicating ECM failure. Most failed ECMs will record a fraction of a volt. To me, the K-Test is simple, elegant, and accurate.

If you are getting low voltage, after performing the test correctly, the ECM is bad.

What voltage do you record, now?

Ok, if I do it that way, I get 0v. All 3 wires show 0v... I also cleaned the ground wires and didn't help. They weren't really corroded or anything but I scuffed them a little anyway..

Your ECM is toast, which is what I suspected. Buy a remaufactured ECM from a reputable auto parts store--shop for price and warranty. Make sure it is an exact Honda Part No. match. Find out what Honda Part No. originally came in the car, not necessarily what's in it now.

Properly ground yourself, before installing the new ECM. Spray the main ECM connector with WD-40, to ease installation.

Here's how this all began maybe this will help... I've been having low idle problems, so I read up on how to adjust the idle. The instructions I found were as follows. Let the car get to operating temp, While the car is running, disconnect the IAC so that it doesn't try to compensate, then back out the throttle body adjustment screw till it idles at about 650rpm.. only thing I did different was disconnect the map sensor so I could get to the adjustment screw easily.. Then it said to shut the car off and connected the IAC back up witch I did but inforgot to connect the map sensor. So I removed the ecu fuse for a few minutes to let codes then put fuse back in and started my car (iac plugged in, map sensor disconnected) the engine light came on so I shut the car off and realized the map sensor was disconnected... I plugged it in, removed Ecu fuse again, then installed after a few minutes and tried to start car but that's when I found a solid CEL and fuel pump not priming...

But I've connected 3 ecms though. Could it at all be possible that there are wires cut or shorted? I don't see how this could have happened. I don't know how 3 of my computers can be messed up.. Especially the last one I tried. That was even looks brand new has not been near moisture or anything

Did you disconnect the MAP Sensor, after the engine was running?

The Manifold Absolute Pressure (MAP) Sensor is the “key” sensor on Hondas. It controls timing (similar to the old vacuum advance on distributors) and air/fuel mixture, depending upon manifold pressure changes. Like any transducer, it converts energy from one form to another. Here, it converts throttle body vacuum pressure changes into fluctuating electrical current signals to the ECM. If this sensor does not receive the proper voltage from the ECM, you will experience catastrophic ignition and fuel system failure. Therefore, I reasoned, begin the diagnosis by testing the voltage between the ECM and the MAP Sensor, because it's a showstopper if this sensor does not receive the proper voltage. The result is the awesome “K-Test” and it WORKS beautifully!

With that as background information, it's imperative that the ECM deliver 5 reference volts to the MAP Sensor. You can go over your wiring harness, but I've never seen a problem there. Invariably, the problem is with the ECM. I don't know why you have three ECMs--maybe they have been shorted out during installation. My best guess is that the problem resides with the ECM, however, since they fail the K-Test.

The only other thing you have not done is check you ignition switch for wear, pitting, or melting. These are high wear items.

No I shut the engine off when I saw the check engine light, then when I looked under hood I saw I didn't plug it in. But I think I figured it out!! Could a cut wire to the ICM IGNITION CONTROL MODULE CAUSE THIS CONCER!! If so, the wire at the Ecu is cut!! Only problem is there are a few wires down there and I don't know witch one connects to it. I had speakers installed and they ran new wires to door speakers so by any chance do you know what wire on the alternator plug would be for the ICM? The engine I have is out of a 2000 Acura Integra type r!! I'm going to look up diagrams and jumper the wire! I'll let you know if this fixes it!

Well I connected the wire and still nothing... Dang it I don't know what's going on. It's just hard for me to believe that all 3 computers I have are bad

It sounds like you need to go over the wiring, before doing anything else. There are more than the normal number of variables right now.

Yea, I'm all out of ideas right about now... I've been on this for about 4 days now my car is stuck at a friends house and I live 30 minutes away. It's hard for me to fix it if I need to find a ride to try and diagnose it. Plus I have no wiring diagrams. This is just not good. And I know I have no spark either because I numbered the fuel pump at the main relay connector and let it prime while I tried to start the car and it wouldn't start.

The first order of business is to get the wiring right. Do you have a friend who could tow your car to your place?

Unfortunately no I have no one to tow it. I go out of my way to help people, but no one ever helps me. You have no idea how much I appreciate you taking the time to help me. I guess I'll try again tomorrow it's dark now

I'm thinking about just buying a whole new engine harness. I'm not sure if mine is OK or not. But if no fuse is bad, of my computer is good, my main relay is OK, my fuel pump works if I jumper it, and I get no volts while doing the k test, there's got to be an open somewhere or something.

Yes, it sounds like the problem is in the harness or switch. Don't give up--victory is close!