99 Civic won't start, scanner cannot establish connection

Merek

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I have a 1999 Civic HX 5 Spd manual and I'm wondering how the pcm/ecu swap went for you last year? My car is at the shop with issues and the mechanic's diagnosis is the pcm, though he isn't 100% and said a new one would have to be "reprogramed" by a H dealership. Could I try to find one at a junk yard with the same part number, out of the same exact model and simply swap it without any dealership involvement?
No they don't, they are either lying to you or don't really know anything about it. They are programmed by the factory and really all you need to do after installing is to let it run until the engine gets to temperature and the fan turns on and you turn off the car and it's set. Supposedly it can learn itself overtime just by driving and meeting certain conditions but I've found it's just easier to let the car idle and let it do it.

If you can find one I'd definitely go with a used one off eBay. I never did find the original one that mine came with so I must've stuck it somewhere. If you don't have emissions testing look for the Federal one and make sure you get one for a manual, A is the one you want, the L is for automatics so stay away from those, last I checked on there it was lots of those but not many of the Federal 5 speed.
 

Merek

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Sorry I should've updated this thread a long time ago, I've been really busy as of late and another CNC is down, hard drive finally bit the dust and their tech support might as well not even exist right now, they were helping at first but now they won't even answer the phone nor respond to email.

I ended up replacing the ecu and it's been fine, I really haven't driven it that much over the last year but everytime that I have no more issues. The one that I purchased is 37820-P2N-A33, the P2N is specific to the HX model and the only one that will work, D16y5 has roller rockers so a different camshaft, egr, and a 5 wire o2 sensor, the P2P is EX.

I think I've misspoke earlier, the A is the Federal but the L is California, the number down low in the 20-30 range are manual transmissions but if it's over 60 then it's automatic, also stay away from P2E that's the D16y7 so non-vtec.

I believe the last set of numbers A31, A32, A33, etc... is just the revision of the ecu.
 

Merek

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But yes you can replace the ecu yourself, it doesn't even take 5 min and is located in the kick panel on the passenger side, it's super easy to get too, just make sure you get a correct ecu that works.
 
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But yes you can replace the ecu yourself, it doesn't even take 5 min and is located in the kick panel on the passenger side, it's super easy to get too, just make sure you get a correct ecu that works.
Thank you both for the detailed replies. That confirms what I pieced together in my research and I am glad I signed up for this forum! I don't think the shop is that familiar with 90s Honda's and I'm not confident it is the ecu. I'll have to do some more digging and try to find a better vetted solution before throwing parts at it.
 

Merek

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What issues are you experiencing? The main relay is another common problem, you have to drop down the glovebox but it's mounted to the right side under the dash above the ecu.
 

Merek

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90's era Honda's for the most part are super easy to work on they really didn't change much from the mid-late 80's up to the early 2000's. You'll have to look for the ecu code when trying to locate one, I know 96-98 was obd2a but 99-00 are obd2b, however the HX's were all obd2a but I don't know if the earlier ecus would work in the later models without cel codes so I'd try to source 99-00 if at all possible.
 
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What issues are you experiencing? The main relay is another common problem, you have to drop down the glovebox but it's mounted to the right side under the dash above the ecu.
'99 HX with just under 200k miles. I've only owned the car a couple of months and it has been running well since I purchased it (I gave it new NGK wires, plugs, cap & rotor, air filter a month ago; prev owner replaced EGR valve and said he had disassembled the fuel rail to clean EGR ports. Overall it was well looked after car with maint records). When I was driving in the pouring rain a couple of weeks back it went from driving fine to the engine losing all power at once. The battery and oil light came on- no other lights on the dash and I still had good battery power (lights, radio, etc).

I had trouble restarting the car. Eventually it would run if I kept goosing the gas pedal, but very rough and erratic. I had it towed where the mechanic said scan tool is showing P0301,2,3,4 misfires for all cylinders. His best assessment is it could be something internal or needs a new pcm. He had replaced the distributor, but it still had the same issues (returned the part without charge). He said it seems the car is flooding out and will only run when stabbing throttle.
 

Astro14

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'99 HX with just under 200k miles. I've only owned the car a couple of months and it has been running well since I purchased it (I gave it new NGK wires, plugs, cap & rotor, air filter a month ago; prev owner replaced EGR valve and said he had disassembled the fuel rail to clean EGR ports. Overall it was well looked after car with maint records). When I was driving in the pouring rain a couple of weeks back it went from driving fine to the engine losing all power at once. The battery and oil light came on- no other lights on the dash and I still had good battery power (lights, radio, etc).

I had trouble restarting the car. Eventually it would run if I kept goosing the gas pedal, but very rough and erratic. I had it towed where the mechanic said scan tool is showing P0301,2,3,4 misfires for all cylinders. His best assessment is it could be something internal or needs a new pcm. He had replaced the distributor, but it still had the same issues (returned the part without charge). He said it seems the car is flooding out and will only run when stabbing throttle.
Previous owner “service” makes me wonder.…

Mechanics who guess make me worry…
 
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Yes you need a better mechanic.

Is it still in the condition you describe where it cranks and fires and sort of runs?

When I was driving in the pouring rain
That may be a useful clue that something under the hood got wet. First thing to consider would be the spark wires but they should dry out in a day or so.
 

Merek

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'99 HX with just under 200k miles. I've only owned the car a couple of months and it has been running well since I purchased it (I gave it new NGK wires, plugs, cap & rotor, air filter a month ago; prev owner replaced EGR valve and said he had disassembled the fuel rail to clean EGR ports. Overall it was well looked after car with maint records). When I was driving in the pouring rain a couple of weeks back it went from driving fine to the engine losing all power at once. The battery and oil light came on- no other lights on the dash and I still had good battery power (lights, radio, etc).

I had trouble restarting the car. Eventually it would run if I kept goosing the gas pedal, but very rough and erratic. I had it towed where the mechanic said scan tool is showing P0301,2,3,4 misfires for all cylinders. His best assessment is it could be something internal or needs a new pcm. He had replaced the distributor, but it still had the same issues (returned the part without charge). He said it seems the car is flooding out and will only run when stabbing throttle.
I know the egr ports all too well, the first time I had that happen it was still under warranty on my 97, Honda had extended the warranty on emissions related parts after entering an agreement with CAFE and extended it to I believe 10 yrs or 150k miles, I received a free tune-up, oil change and the ports cleaned out, I think they also replaced the o2 sensor at some point as well under warranty. The ecu on that car went out just before it expired so I asked them how much a new one was and they said $700 so that had to be previous to 2007 for it to still have been under warranty. I think the ports needed to be cleaned at around 115k miles and I've had to clean them since myself.

The 99 I fought with egr codes as well, there are two different codes for that and not very specific, it's either the valve itself or the ports. I had that car serviced with about everything, timing belt, water pump, etc.... and asked them to clean out the ports while they had it. With that one I basically started over myself from scratch digging into it, I had put some miles on it since but did appear they had cleaned them because it wasn't too bad when I got in there. It ended up being the egr valve, I swapped the one from the 97 over and tested it, I didn't want to spend several hundered from Honda if I didn't have too, I left it like that and then purchased one for the 97.

Gun cleaning brushes work very well for cleaning those ports out, I like the plastic ones the best though and don't have to worry about the metal breaking off into the engine.
 

Merek

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Do you have one of those cold air intakes on your car? I know if you drive through a lot of water they can suck water into the intake. I never used one but they were very popular back in the day.
 
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Do you have one of those cold air intakes on your car? I know if you drive through a lot of water they can suck water into the intake. I never used one but they were very popular back in the day.
Thanks again for replies. No cold air intake on the car, all original survivor. I agree with it not being the most clear diagnosis. Next week I can call around to junk yards and try to find a PCM, should be under $100. Not sure if I would be able to tell by looking inside the old PCM to see if it was fried or how to truly find the best sign of what was actually causing engine to flood at idle and misfire.
 
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A skipped timing belt should be considered when there is an instantaneous decrease of performance that never comes back. This is very easy to check by removing the upper cover, setting the crank to TDC and make sure the cam pulley is on the marks.
 

Merek

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If the belt breaks these Honda motors are not relieved to clear the valves when it breaks, you'd be looking at bent valves and all kinds of serious carnage if that were to happen.
 

SammyChevelleTypeS3

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I have a 99 Civic that won't start, it cranks over fine but when you turn the key to the run position the fuel pump doesn't run. I found that when you turn the key to run that the check engine light doesn't turn off after a few seconds which should mean there is a code stored but my scan tool says that it cannot establish a connection with the vehicle. I had replaced the main relay a few yrs ago as that's a common issue on these Civic's from that era but also found there can be an issue with the ignition switch. It looks fairly simple to change out, it's the electrical part which is a separate piece that doesn't include the actual switch with the tumblers and I won't have to worry about having 2 keys or having it rekeyed to the car.

The switch when it fails the car can shutoff when you hit a bump in the road or if you have a lot of keys on your keyring which I believe GM also had that issue if anyone remembers. I do have a new switch on order and hopefully should be here tomorrow but was wondering if that could be preventing power to the ecu, I've checked the fuses under the dash and under the hood but all were good. I actually do have another ecu that was in the car when I bought it that is if I can find it, I've looked this evening and struck out, it's way too hot and I'm too tired to keep looking right now. The car is actually CA emissions and I replaced it with the most recent Federal one, I live in VA and they only test if you live in Nova which I do not reside there. I'm hoping the switch solves it but if not then I'll have to find it.

I haven't done this yet but there is a brown pigtail connector at the ecu that you can short with a paperclip and count the flashes on the light to read the code. I literally had taken this thing to the dealer a few weeks ago and had them replace the airbag inflater under the recall and really haven't driven it much since.
The starting switches.... Oh yeah. Had to replace the one in the 1994 F150 when it self destructed. Got to the point you could start without the use of a key. Sorry for the encyclopedia sized comment but you reminded me of some of my last hands on repairs before I ended up disabled.
Sometimes they (Hondas) will jump timing from the battery going weak after trying to start it over and over, If you know what to listen to / are familiar with the normal sound your car makes when you start it you will surely know it is not going to be long out of the shop. Changing the starter on the Hondas from 2007 thru about 2012 models is not an easy / quick job. My 2009 did that when the starter and battery were both going bad. I also had a weakened original wire that was shorting out and that took a good bit (we were wiped out) to locate when all this was going on. The cam position sensor can get thrown off also when all this starting and stopping stuff is going on. If that happens you will end up (for protection of your engine) need to tow it in cause it will not run on all 4 cyclinders. That is the only (what I call major repair) ever needed on the 2009 2.4L Accord we still own. She is still running along like new these days with well over 175,000mi. I am lucky to have a really good friend (honest) who has owned (30+ yrs) his own Independent foreign car shop less than 5 mi from my house. If I ever need them they take the car into the shop and drive me home. Once repairs 100% they drive it to my house and we take a 10-15 mile test run before I drive the guy back to the shop and pay him. That last incident with all those little nagging issues it was in the shop a week plus he had to consult with Honda dealership. They tried to discourage him and to tell him he should give up and bring it to them for replacement of the ECM unit for an additional $900 to $1400 without even looking it over. He declined and told them he had it worked out. He ended up knocking $900 off the invoice and even replaced the ECM unit with one he had been having in the shop and felt he would not need. This guy became a good friend years ago when I would run across little nagging electrical issues with my full size Ford Bronco I used for pulling boats for hunting and fishing. I would take it and my F150 truck to him and after telling him the issues and being prepared to drop them off.... he would tell me what and how to do the repairs at home saving me lots of cash. He taught me lots of troubleshooting with Ford's excessive power window issues in the 90s and even guided me thru the complete rebuild of the front end of those 4 wheel drives. Gave me books and disgrams to follow with all that suspensions work.
 
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The 1999 generally has none of the stuff that SammyChevelle was talking about.

I have not experienced it personally, but I have heard of the D series timing belt skipping a tooth or two without completely stripping. The engine might still run -- badly. Generally the symptom of being off by one tooth is it starts but it has very little power and won't rev over 3000 rpm.
 

SammyChevelleTypeS3

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The 1999 generally has none of the stuff that SammyChevelle was talking about.

I have not experienced it personally, but I have heard of the D series timing belt skipping a tooth or two without completely stripping. The engine might still run -- badly. Generally the symptom of being off by one tooth is it starts but it has very little power and won't rev over 3000 rpm.
ooops.... sleep in my eyes did not catch 1999. Sorry. Only a complete 10 years off! 😳
 
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I appreciate all the replies. I asked the mechanic about skipped timing and he was able to explain why he doesn't think that is the case. I'll start with replacing the PCM and go from there. He told me I could take care of whatever I want with my car in the lot for the next 2 weeks. I pulled the kick panel and opened up the PCM to look for any obvious damage (didn't see anything)....but it seems strange that the part # 37820-P2N-L33 matches that of a 2000 model year Cali emission car when it has spent it's entire life in Delaware (records and carfax show this). So I'm on the hunt for a Federal version of 2000MY, part#37820-P2N-A33 ?(I was reading the 1999 PCMs are known to have a higher rate of failure, so I figure 2000MY is the way to go)
 

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Merek

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I appreciate all the replies. I asked the mechanic about skipped timing and he was able to explain why he doesn't think that is the case. I'll start with replacing the PCM and go from there. He told me I could take care of whatever I want with my car in the lot for the next 2 weeks. I pulled the kick panel and opened up the PCM to look for any obvious damage (didn't see anything)....but it seems strange that the part # 37820-P2N-L33 matches that of a 2000 model year Cali emission car when it has spent it's entire life in Delaware (records and carfax show this). So I'm on the hunt for a Federal version of 2000MY, part#37820-P2N-A33 ?(I was reading the 1999 PCMs are known to have a higher rate of failure, so I figure 2000MY is the way to go)
The same with mine here in VA, if you actually look under the hood it will say California somewhere, I can't remember either the hood or the radiator support. I think what happened is that to fulfill demand they used those CA cars throughout the country, I also read that some manufacturers opted to sell CA emissions vehicles in all 50 states. I would definitely look for an ecu with the 49 state emissions, if anything you'd get better mileage. When I swapped it in mine there wasn't any codes or anything and I really did the research trying to figure out what's different between them and the only part that differs is the ecu so it's the fuel mapping.

Evidently the A33 is no longer available new, they are still offering the A32 so I would try to get one of these two.
 
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I appreciate all the replies. I asked the mechanic about skipped timing and he was able to explain why he doesn't think that is the case. I'll start with replacing the PCM and go from there. He told me I could take care of whatever I want with my car in the lot for the next 2 weeks. I pulled the kick panel and opened up the PCM to look for any obvious damage (didn't see anything)....but it seems strange that the part # 37820-P2N-L33 matches that of a 2000 model year Cali emission car when it has spent it's entire life in Delaware (records and carfax show this). So I'm on the hunt for a Federal version of 2000MY, part#37820-P2N-A33 ?(I was reading the 1999 PCMs are known to have a higher rate of failure, so I figure 2000MY is the way to go)
I can't really tell for certain, but it looks like the small electrolytic capacitor just below and to the left of the center screw has leaked and corroded part of the printed circuit board. This was a very common occurrence on early/mid '90s Honda Accord transmission control modules (TCMs). I have fixed a few that were not badly corroded by un-soldering the bad capacitor, cleaning up the board with Q-tips using vinegar and alcohol and soldering in a new replacement capacitor. Look closely for signs of leakage under that capacitor and a possible "fishy" smell which is associated with the electrolytic fluid (as suggested in post #17).
 
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