This 2001 Honda Civic came in with a multitude of problems one of which was a code P1298 stored for an ELD fault (electric load detector circuit input high). I had never had to actually test one of these before although I knew that they existed. The ELD sends a signal to the engine control computer so that the computer can adjust the alternator output in relation to power consumption. The ELD is located in the underhood fuse box. I am pointing to it with my screw driver.
To test the ELD I had to lift the underhood fuse box and remove the bottom cover. Once removed I could access the wiring for the ELD. The wire on the far right of the connector is power supply (battery voltage).
The wire in the middle of the connector is battery ground.
The wire on the far left of the connector is a five volt signal sent from the computer. The ELD will pull the voltage lower with increased system load and should vary with a change in load. For example if the blower or headlights are turned on it should drop. This particular unit was stuck at 3.81 volts and would not change with no loads or full loads applied. If the voltage had been near zero I would have had to unplug the connector and see if the five volt reference signal was being sent by the computer and wiring.
After testing and finding a faulty ELD, it was very easy to change. I removed the four adjoining phillips headed screws that held the two PAL fuses in place.
I released the latch on the harness connector and unplugged the connector.
With the wiring removed I simply lifted the unit. Slid the bar out and installed the new unit.
Below are a couple of pictures of the actual ELD part from Honda.
Hi there,
Like many of the posters I’m having a similar issue, and wanted to add a more specific description in case it helps to lead others to the right answers… My wife has a 2003 Civic EX (automatic). Recently, she’s encountered a problem most similar to that of Jason’s (Sat Jun 04, 05:53:00 PM 2011) – similar, but not identical. It began this winter, so unclear whether it’s weather-related, but when the car is driven a short distance, stopped, and driven again a couple of times, after maybe the second or third start, within a few minutes of getting moving, you’ll be int he middle of driving and the car suddenly stops paying attention to the fact that your foot is on the gas – seems like it’s stuck in 1st or 2nd, but, in contrast to Jason’s problem, the engine does not rev *at all*. I drove her car recently and was able to experience it myself – tried shifting into 2nd and low and back again but it didn’t help. I went to neutral and then park after pulling over, then back to drive, and it was OK again, but it’s always been intermittent anyway she said, so it may not have been anything I did. We had to get a recall repair recently anyway, so we asked the dealer to have a look – the code they got was P1298 ELD HIGH VOLTAGE SENSOR FAULTY – nothing else. They replaced the ELD sensor and cleared the code, though I don’t know if they actually tested the ELD before replacing it, since my understanding is that this sort of thing can be caused by wiring faults elsewhere as well. They also indicated some damage on the spark plugs and replaced those as well. So, after we pick up the car, we go to Home Depot, my wife pulls out after we’re done and on the way out of the parking lot, with me behind her, the car does the same thing again. Clearly not fixed. Any thoughts would be most welcome. Thanks in advance!
-DS
Sparky,
I figured I would update you since that is the point in posting to ensure that we help one another. So to answer your first question, yes the CEL came on after I replaced the ELD. Actually, I cleared it 3 times and it kept coming back. Again, it is so odd that the CEL comes on after driving for close to two hours. Sometimes it comes on after I have driven for two hours, stopped and then it trips on my way home and other instances it comes on during my initial trip within around a hour and half of driving. I checked the voltage on the ELD. I assume this has to be done with the car running since there are no usable readings otherwise. With the car running, the voltage on the wire to the far right matches the battery (around 14.5), ground is around 1.0 and the far left wire is around 3.7 without load and 2.6 with headlights, heater and radio on. So it seems like it is functioning properly. I looked for a short and found nothing. I took off the couple grounds around the transmission (3 I think) and cleaned them and reinstalled them. I cleared the codes after everything was done. As for the O2 sensors – I went ahead and changed them both while I was under the car. I know you said it could just be the primary but neither of them were that expensive so I figured what the heck. Neither one had any visible damage. I started the car 3-4 times and drove it for about 15 minutes and no CEL. As with past history, I know that the CEL hasnt come on unless I drive it for a while so I will have to see what happens tomorrow when I drive it. I will give you updates as we go so you know what the resolution is. I have heard of someone replacing the O2 sensor and it fixed both codes. I really hope that happens. If I get the P0420 code again I will order a cat and let you know what happens. If I get the P1298 again, I will be at a loss since I wont know where to turn. So I’ll post in a couple days to let you know my progress.
Chris
You left some room for guessing. Did the P1298 return after replacing the ELD and clearing the codes? If so, you would need to monitor the five volt signal between the ELD and the PCM. It would be likely that there is a loose connection on that wire. As far as the P0420 goes, the converter may have to be replaced. However since you already have the O2 or A/F sensors, remove the pre catalyst sensor and inspect it for physical damage. If no damage is found install the new sensor. Leave the old post catalyst sensor in place. Clear the codes and drive the vehicle again. The P0420 may not return. Sometimes a lazy front sensor will fool the computer into thinking the catalyst is not doing it’s job.
Sparky,
First let me say that you are a wealth of valuable information and I thank you for your posts. I am quite knowledgeable and experienced in mechanics (not ASE certified). I am a bit baffled on this one as I have never asked a question online before. I bought an 02′ Civic EX 6 weeks ago. Long story short – I ended up rebuilding the manual tranny two weeks ago (bad input shaft bearing). I never drove the car more than 20 minutes at a time before the tranny was rebuilt. On my first trip to work (110 mile commute each way) the CEL came on after about 90 miles. Codes were P1298 and P0420. I cleared them that night. Car sat all night and I drove it to work again. No CEL on the way there but it tripped about 5 minutes into my return home. Same codes. Cleared them again. So basically, they are quite intermittent but somewhat predicable. I replaced the ELD since it was cheap and cleared them again. Once again, CEL tripped. This morning – I drove about 70 miles, stopped for gas and the CEL tripped about 5 minutes after restarting. No blown fuses, no short that I have seen. I assume the 0420 is a less than efficient cat (which the light comes on when it is below 95% which is crazy but I will have to replace since I have emission testing in MD and they wont even look at the car with a code). Now that I have written a book, your best guess? Short somewhere tripping ELD? If it is a short, why is it kind of predicable? Wouldn’t a short trip at different intervals? I can almost guarantee that the CEL wont trip for an hour or so after I clear the code. I bought both O2 sensors but am reluctant to install them because I don’t think that is the real problem. Also, no performance affected. I saw all the talk about the alternator but I would think that I would trip a CEL a bit sooner than 1 1/2 to 2 hours after beginning my commute.
The shorted O2 sensor wiring could definitely have been the cause of the fuse blowing. Are you sure that the harness going to the O2 sensor is okay? It is possible for the PCM to have been damaged but normally only the O2 signal and heater circuits would have been affected. Do you actually have a ELD code or any other?