Hi,

I spend some time searching around, but didn't have any luck with my specific problem, so if someone knows of another thread, please let me know.

My 2003 Civic EX developed some issues a few weeks ago and I'm trying to track it down and could use a little help. I took it to the shop a few weeks ago, but don't have the cash to have them fix it, so I'm gonna try the DIY route.

I have three issues, which the shop seemed to intimate could be related to each other. 1) My speedometer has stopped working 2) My check engine light and battery light are on 3) I experience intermittent stalling.

The shop said that the VSS and O2 sensors were giving codes and that the fuse box needed to be replaced, but that replacing the fuse box might clear up the other two issues, so I should replace that first. From looking at the receipt, it looks like the issue specifically with the fuse box is the ELD (electric load detector). I ordered that part and installed the new ELD last night, but still no change in my problems.

I guess my question is would the fuse box itself really be causing the issues? I looked it over last night whilst replacing the ELD, and it looked to be fine to me. The shop seemed to indicate that the problem was the ELD, but that the whole fuse box needed to be replaced.

Anyone have any thoughts?

Any help is much appreciated!

Drew

 

BTW, codes are:

P0141
P0135
P0500

I believe two are the O2 Sensors, the other is the VSS.

 

When they said to replace the fuse box, did they specify which one? They may have been referring to the fuse box under the driver's side of the dashboard, which has the MCU (multiplex control unit) built into it. I have seen cases where a bad MCU has caused multiple issues, all of which were fixed by replacing the interior fuse box. Then again, I've also seen cases where a slowly-dying alternator caused all kinds of weird issues, too. Electrical problems are a PITA.

If you can source a used interior fuse box, that's great. New ones are not cheap. If you just want to buy a new one, the best price will likely be from Majestic Honda. (click the link)




And you are correct; the P0135 and P0141 codes are for the primary and secondary O2 sensors. P0500 is VSS Circuit Malfunction.

 

Hi IWM,

Thanks for replying!

Sorry, I meant to mention that it's the fuse box in the engine compartment. What you're saying makes sense. I could see something being wrong with MCU causing problems, however everything they've told me thus far indicates they thought it was the engine fuse box. Granted, I don't know a whole lot about cars, but that doesn't make sense to me....but, like I said, I don't know a whole lot about cars .

And hopefully it's not the alternator, as I just had it replaced less than a year ago.

One thing I noticed last night as I was doing some poking around is related to the intermittent stalling I've been experiencing. It will idle fairly normally, but then when the fans kick on, the engine struggles a bit, then returns to normal. Then, same thing once the fans turn off again. Monitoring the voltage as this occurs, it will droop as the engine struggles, and then bounce back again. I'm assuming that it's an electrical problem that is causing the engine to struggle when the fans kick on and off, or when there is a large electrical load.

Any thoughts off hand of anything in the engine compartment fuse box that could cause these issues? I read a few threads suggesting a new ELD, but as I mentioned, I replaced that already and no change.

Thanks again!

Drew

 

I have got a couple of tests to perform before you start trowing parts on your car.For sure it is very hard for me to see what's exactly going on with the car,(without of scanner especially)but I have got a case with 2007 Honda Fit. Similar trouble in a way that when the fan kicks in the motor just cuts intermittently.No codes however.The problem was a leaky ignition coils.Three of them were leaking voltage and grounding themselves before reaching to the spark plugs.This test won't cost you anything but the spark tester and a piece of wire.Take one by one coils out of it's place (with the spark tester connected to it) start the engine and grounding one side of the wire go around and along the coil.Make sure there are no voltage leaks.

 

Radiator and condensor fans are controlled by the multiplex box, as it is computer circuitry one cannot tell if it is dead visually. It wasn't me has posted a instrument cluster self diagnosis link, try it to test your cluster. Multiplex boxes are absolute junk, they do not age well, if you are going to try to replace another component I would try that one. American Honda prices are very reasonable, about a third of Honda Canada inc's pricing, just for adding daytime running light function. Good luck.

 

Hi guys,

Thanks for the replies. I'm at work right now, but I'll try and take a look at these suggestions hopefully tonight or tomorrow night and report back what I find.

Drew

 

eviee1973,

Was this the link you were talking about?

https://honda-tech.com/forums/showthread.php?t=2908290

I didn't see anything about testing the MCU. Is there a way to test it specifically other than swapping out the part?

Also, I'm going to try to test the ignition coils as soon as I can get to the auto parts store. Report to follow.

Thanks guys!
Drew

 

Yes that was the cluster self diagnosis link, it's not even in the Honda shop manual. There are multiplex self diagnosis which can be performed as per Civic shop manual, however they do not provide a conclusive failure with intermittent problems. An air conditioning electrical problem apperas to have been caused by mine, however testing indictated everything was ok. Finally my Civic'c multiplex box did a complete failure, yet somehow managed to recover, after frying my alternator.

 

OK...sorry for the delay...super busy holiday.

BUT...yesterday I fixed the problem! It was a dead fuse. I put my car up on jack stands and looked underneath and found a wiring harness that had broken loose from the chassis and had a wire sticking out that I think shorted to the chassis, blowing the fuse. So, I taped up the harness, secured it and replaced the fuse. All systems go!

Thanks for all the help and suggestions!

Drew

 

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