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My check engine light just stays on, and when I jump the data link connector Im not given any codes. I took it to my mechanic and he told that it was short to ground, and he is unable to pull codes until that is fixed. Im not sure which wire to follow from the ecu, or where it may be grounded. Any help is appreciated.
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I’m not sure I subscribe to that theory, what tests were done to make this determination? If he really went through any testing you would have a good idea where the ‘short to ground’ was. First check all the fuses as a blow fuse can cause that problem. Also try resetting it by disconnecting the negative battery cable and touching it to the positive cable for a few seconds and then reconnecting it to see if that changes anything. Lastly if the ECU got wet due to a leak or someone spilling stuff on it take it out and let it dry out for a bit and then reinstall it to see if it works then.
RealFixesRealFast has an excellent video for tracking down shorts with using basic equipment. If the diagnostics system isn’t working correctly then it could be your diagnostic box (I don’t know your system) or DLC connectors are the culprits. Trace back the wires from your DLC connectors and inspect the wiring. It’s probably going to be a rubbed-through wire somewhere in the engine bay simply because that’s where the most vibrations occur. You’ve got to get your hands on them and visually inspect them.
Might not be a bad idea to check the health of your diagnostic system by disconnecting an O2 sensor or MAF and then rechecking for codes. That’s a quick way to tell if it’s your diagnostic system at fault or sensors.
Another probable scenario is that the sensor(s) are dead. You have a 16 year old car and chances are good if the sensors have never been replaced there could be multiple dead sensors.
Are you blowing fuses like the MAIN fuse?
Does your car run at all? I would think that any short to ground from the ECU would cause a lot of problems.
Sorry for the late response if any one replies at this time. I’ve got no blown fuses, and I took apart the glove box and passenger air bag and followed the wires and didn’t find any that were out of the norm. The only part of the wires i couldn’t back track were way in the back along the fire wall, but that was only maybe six inches of wire. So I put it all back together and it gave me a vtec solenoid code(code 21), but it keeps blinking the code now! I’m not jumping the DLConnector either, its doing it on its own. My mechanic told me he cut one of the wires to bypass the dlc, and found it was short to ground. I figure the solenoid is the easy fix, but my main concern is the check engine light acting up. Thanks for all the responses.
You might have an ECU problem but as for the short to ground your ‘methods’ of diagnosis are in question as I’ve never known cutting wires to be a part of electrical diagnosis. Normally with a problem like that you need to check all the inputs and outputs for the ECU to verify if it’s getting and sending the correct information in addition to checking it’s power inputs. I don’t think your VTEC solinoid has anyting to do with it, I would be checking the input for the solinoid into the ECU to see if there was an issue there. It does sound like you have an electrical issue but I’m not sure that the ECU is at fault. To be honest I think you should take it to a qualified mechanic to have it properly diagnosed because it sounds like you and your mechanic may be in over your heads. The only thing I think you could do at this point that MIGHT be of some benefit is to remove the ECU and inspect the board for any signs of damage, even if you find some however the damage may be a symptom and not the cause as you may hook up a known good ECU and blow that one too if you don’t find the root cause. Good luck.
[quote=”EricTheCarGuy” post=21904]I’m not sure I subscribe to that theory, what tests were done to make this determination? If he really went through any testing you would have a good idea where the ‘short to ground’ was. First check all the fuses as a blow fuse can cause that problem. Also try resetting it by disconnecting the negative battery cable and touching it to the positive cable for a few seconds and then reconnecting it to see if that changes anything. Lastly if the ECU got wet due to a leak or someone spilling stuff on it take it out and let it dry out for a bit and then reinstall it to see if it works then.[/quote]
Hey Eric, been watching your videos for a long time. sorry to dig up this old post but i have recently been having an issue with my 1994 legend . I have come to also believe that it is potentially a short to ground inside of the ecu. Let me back up a bit there, I had replaced the alternator with an oreiley reman. witch i am guessing either caused or made this issue worse . thing was throwing almost 17 v at the battery. Before i was able to return and replace it the car exprienced some sort of surge and then shut off. Come to find it had fried the cooling fan fuse, cooling fan relay, and ecu fuse replaced all and tried to fire it, now it’s just blowing the ecu fuse/fuse 5 every time. If i remove the main relay the fuse will not blow when i turn car to “on”. so i started unplugging connectors to try to locate a short and bingo IAC connector is short to ground. traced the short back through the loom untill i unplugged the ecu. and boom short to ground dissapears from the whole of that yel/blk whire that runs from main relay to fuse box to relay box c and iac and everything. So now i am looking for an Ecu for the Elusive 94 6spd blk sedan! Any help would be greatly apreciated. I firmly believe that if i didn’t own this car it would already be in the junkyard, but i am commited to keeping it on the road.
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