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Hi y'all. We got an 01 Civic EX 2 door coupe here with the 1.7 VTEC engine. Problem is it won't pass emissions because the OBD monitors reset with a key cycle. Usually this is straightforward as the Backup fuse is often blown. While this has a Backup fuse and it's not blown, the wiring diagrams do not include it. In fact, all the wiring diagrams I've been able to obtain thus far show no constant power to the PCM. Very odd indeed. The owner states this has been going on for years and he had an Inspection station that was 'just passing it' but they won't pass it anymore. (LOL) He also states that it started when an aftermarket alarm system was removed (he thinks). I've done a visual and saw nothing out of the ordinary.

Does anyone know how this vehicle retains it memory or has experience with a similar problem? If the PCM has constant power as I think it should, I need to know on what circuit. I've even checked all the PCM pins on the chart and saw no constant power. Maybe it does it internally with a capacitor?

ric,

We have seen similar issues on a few odd makes/models. We have been able to trick the NY state inspection computer by not shutting the cars off during the OBD2 test. I am not sure if the NH inspection computers are the same, but ours walks us thru an OBD2 check, which is basically a 2 step process:
KOEO- does the MIL come on?
KOER- checks for codes and monitors

If we never shut the car off for the KOEO test, we can still get the car through the procedure. It appears that no real communication occurs between the state and the vehicle during this process.

On a side note, we recently had a 2000 Audi A4 that would not talk to the inspection computer. We could communicate with the vehicle via multiple scanners... or so we thought. It turns out that the ABS module interrupted the network only when the engine was running. We were verifying scanner communication KOEO. Oops.
So, with the ABS module unplugged, the car went through the inspection nicely.

As far as specific Honda issues, none come to mind. Although I do recall reading about certain year/model Hondas that did not truly meet the emissions criteria and had to work out a deal with the Feds. The details elude me.

I have no doubt we could trick this vehicle into passing. Our system is similar to yours, however, there IS a step that asks for the vehicle to be off for 30 seconds prior to testing. That would nix this vehicle. If I lied and said it was off, it would pass. Chances are that is was what the other shop was doing until they got caught or were being watched.

There is a list of con-compliant vehicles for NH testing. This Honda is not on it (yet).

ricmorin wrote:I have no doubt we could trick this vehicle into passing. Our system is similar to yours, however, there IS a step that asks for the vehicle to be off for 30 seconds prior to testing.

Yup, that 30 second wait is on ours as well.

ricmorin wrote:Chances are that is was what the other shop was doing until they got caught or were being watched.

Yikes! Perhaps we need to reevaluate the circumstances regarding when we trick these kinds of vehicles in the future.

ricmorin wrote:There is a list of con-compliant vehicles for NH testing. This Honda is not on it (yet).

I think we had a Volvo awhile back that went through automatically even though the monitors reset every time the key is off- by design.

I have no other helpful advice. It is an odd bird, for sure. Have you verified with a scanner that the monitors are indeed resetting?

Yeah... and funny story. I have a MasterTech with the factory Honda card...factory tool for the day. On the Honda tool monitors were going from set to not set on road test. We know that doesn't happen. So I used a generic code reader and found that they were being reset and staying that way. There's a TSB on software update for communication issues with the factory tool. Ugh!

BTW, I'm not positive that the machine knows if you perform the key off portion, but they upgrade the software a lot. Who's your vendor, Gordon Darby?

Not sure what you mean by "vendor". The company that oversees the equipment and infrastructure is called SGS Testcom.

We have the VCI with Honda/Toyo OE software.

Help me to clarify what I am reading from your post:

1) are the monitors resetting during the drive or you notice them reset once you restart the car?

2) can you get all the monitors to run during a road test?

From the schematics I looked at, I also see no constant power feed to the PCM. Never noticed that before. Weird.

By Vendor I mean the provider for your emission testing.

The monitors only reset during a key cycle. The factory tool indicated otherwise, but was malfunctioning.

Yes, I can get them to run during a road test. Of course, the evap monitor requires 2 trips, so that one never completes.

Just for the fun of it, I Googled "2001 civic monitor reset" and came up with this: http://www.driveaccord.net/forums/showthread.php?t=7261

Towards the middle they start talking about a weak battery. I have seen weak batteries turn on SRS lights before... maybe this is resetting the monitors?

Just something to think about.

I'll keep digging as I am able.

Yes, I thought the same. I tested the voltage during crank and it dropped to 9.6, so I substituted a good battery which only dropped to 11.5. But it reset anyway. Bummer.

Thanks for all so far. I've also posted this on iAtn.

Another suggestion: did you look at the schematics for Civics that are a year or two older & younger than your problem child? Sometimes I have found that wiring diagrams don't get updated properly when production changes occur.

LOL. Great minds think alike.

Sure did. The 2000 model had the 1.6 engine and it did indeed have constant power. The 2002 looked identical to the 2001.

You probably learned the hard way like I did to always check this when things look weird or don't make sense.

Oh! How many are the bumps on my head that match the dents in the walls...

Hmmm... I vote for wiring the PCM feeds straight to the battery!

Did you check all the pins at the PCM to determine if all had some sort of signal? Perhaps you might find a "dead" one that might be the mystery backup feed.

More random thoughts:

Harkening back to the comment about the alarm removal- is there evidence of an alarm that, perhaps, was wired into the DLC?

Does it by chance have an aftermarket stereo? Did you disconnect it and check the monitors? I thought I read somewhere about backyard installations going bad when the units get wired into a communication circuit ("K line"?? or something). Not sure if this model is susceptible to this or not. I could also be imagining things.

Did you check all the pins at the PCM to determine if all had some sort of signal? Perhaps you might find a "dead" one that might be the mystery backup feed.

Did not backprobe each one. I did go through each designation on the print-out to see if one could be the backup. I figured if I found a 'dead' one, how would I know for sure it wasn't supposed to be dead? Good thought though, may try that when vehicle returns.

Harkening back to the comment about the alarm removal- is there evidence of an alarm that, perhaps, was wired into the DLC?

I found where they tapped in. Looks like they used a connector for an optional OE alarm system. I assume it wasn't included since it's not currently there. I also checked to see if there was some relationship to this missing optional module and memory retention in the PCM and could find none. Wiring wasn't butchered; just used those splice locks. Again, good thoughts.

Does it by chance have an aftermarket stereo? Did you disconnect it and check the monitors?

Another good thought. It has a an OE stereo, BUT...... the time is flashing, reads correctly, but flashing. I thought that was odd, but couldn't find any relationship. That may require further scrutiny.

Ric, We have had a few Fords with this problem. The keep-alive signal was good but would still reset everytime the key was turned off. I have never seen this on a Honda but if it does infact have an internal capacitor, then it may have failed.

A fellow member on iAtn may have found this problem. Pin 7 on connector E31 is powered all the time, but it's the feed for the main relay. The PCM grounds this to actuate the relay, HOWEVER, it is labeled Power source for the DTC memory Signal. OK. So my take is the PCM uses the 12v there key-off to maintain memory, then grounds it to turn on the relay. That's a new one on me. Vehicle is not here but will be back next week. I'll post an update, but if my conclusions are correct, this Honda will probably need a PCM.

Thanks everyone so far!!!!

Sounds a bit bass akwards to me. The keep alive memory relies on the relay to trigger when key is off. I noticed that on a wiring diagram i was looking at and i didn't quite understand it. I got the impression while looking at it that it was a double feed, if i recall correctly it was a yellow wire. If this were true then there needs to be a capacitor in the pcm to maintain a feed for the momentary power outage. another point here, wouldn't there need to be a diode in the fuse box or somewhere to avoid a feed back issue? I've been away from wiring long enough to miss the obvious and get in a lot of trouble.