1990 Accord Check Engine Light Problem

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  #1  
Old 10-09-15, 09:09 PM
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1990 Accord Check Engine Light Problem

1990 Accord LX, 4 dr, AT, 259,807 miles. Check Engine Light won't come on for 2-3 seconds after turn on ignition key. When it is a very hot day with all windows up (inside car at least 120 degree Fahrenheit or above), CEL will come on for 2-3 seconds right after turn on ignition key. When it is not so hot day and even it is around 100 degree Fahrenheit inside, CEL won't come on when turn key to on. Other than CEL problem, all others are normal, easy to start engine and radio is normal. It has been like this for many years and O2 sensor has been changed with no help to resolve CEL problem. This will fail smog check and my smog check is coming in a couple of months. It was working intermittent two years ago when I had smog check, but not any more. Does anyone know where to check and how to fix it?
 
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  #2  
Old 10-09-15, 09:19 PM
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Right after you turn the key on or right after you start it ?
The check engine light usually comes on when you turn the key on and before starting engine.

If the computer senses a problem it should be stored as a retrievable code.
 
  #3  
Old 10-09-15, 09:34 PM
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CEL should come on for 2-3 seconds right after I turn key on before starting engine, but it won't come on. There isn't any code stored.
 
  #4  
Old 10-09-15, 11:55 PM
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probably need a wiring diagram for a starting point then you could check the terminal for the check engine light at the ecu as its fairly easy to access generally the ecu would supply ground to the circuit for the function test but a wiring diagram would tell you for sure and let you know witch terminal to check with a volt meter to see if it is supplying ground to the circuit for a couple of seconds after turning key on.
if the ecu is working then your probably looking at a bad connection maybe a bad bulb seeing how it comes and goes would follow the wiring diagram from the power source checking that power is going through the fuse block then next spot to check voltage would be removing the instrument cluster.
 
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Old 10-10-15, 07:32 AM
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It has been stated to me by these professionals, quite emphatically, that the ECU is the LAST thing by far that ever goes wrong with a Honda's engine control system. I have also been told that an amazing number of people blame that mysterious black box for just about everything that goes wrong with their car, probably because they have no idea how it works.
A few anecdotes do not a trend make. I cannot use a few emailed anecdotal accounts of ECU failure to go against what the pro's tell me.

There are some auto manufacturers who are notorious in the trade for installing ECUs with poor durability, but Honda is not one of them. Remember that the ECU/ECM is fundamentally an emissions control computer. Honda has been "green" since the early '70s, with its landmark CVCC engine. Honda takes emissions and quality very seriously, and commits appropriate resources to both.

Now, there is an important point to be made here... There are two primary telltales for a healthy ECU/ECM:

The behavior of the Check Engine light. If, when you first turn the ignition key to "II", the Check Engine light comes on for two seconds, the fuel pump runs during those two seconds, then the light and fuel pump shut off after that and the light stays off, the ECU is FINE. Whatever's wrong with your car, it's not the ECU.
The presence of an error code behind the light. If the Check Engine light comes on solid and never goes off, comes on while the car is running, or takes a long time to go off, and there is no error code stored in the ECU, the ECU MAY be faulty. However, other problems can cause a no-code condition, such as pinched, corroded or crossed wires, which is why I say "MAY". You have to do some primary diagnostics before replacing the ECU.

So there you have it: if the ECU was bad, you'd have clues. If those clues are not present, look somewhere else for your problem. Even if the clues are there, you STILL need to check for things like a disconnected ECU ground wire, missing engine ground strap, pinched wires, crossed wires, that sort of thing. These can all cause symptoms similar to a bad ECU.

Finally, if you're the sort who is comfortable removing the top from your ECU and inspecting the guts, you can probably use that as a way of telling if your ECU is bad. From my understanding, failed components are visually very obvious, exhibiting signs like leakage and bursting. If you're handy with a soldering iron, you can likely replace those components (provided the circuit board is not compromised), which are commonly and cheaply available from electronics stores the world over.



If car runs fine and it's more of a nuisance, I'd simply let it be. What gives. Maybe do the jumper clip thing and read codes anyway.
 

Last edited by ukrbyk; 10-10-15 at 07:48 AM.
  #6  
Old 10-10-15, 09:54 AM
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Thanks for comments and suggestions. I have left this problem for > 4 years. Here in CA, we do smog check every two years. This problem was intermittent and had 50% chance come on for 2-3 seconds when first turn key to II position two years ago. It failed smog check 1st time two years ago due to CEL didn't on. However, it was working normally after 20 minutes. I had smog check again and it passed. It is now constantly won't come on unless the very hot day with all windows up. I will need smog check in a couple of months and need to fix this problem before smog check.
 
  #7  
Old 10-10-15, 01:23 PM
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It's electronics if it's temperature related. Out of curiosity, put bag of ice where ECU is. It's normally, for your year, somewhere in the floor, most likely, under pass side floor panel where feet go. Even open the kick panel and put ice onto ECM case. If it fixed the issue - well, you got your answer. Heck, I'd go do smog with that in place.
 
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Old 10-10-15, 03:32 PM
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ukrbyk, I think you misunderstood my problem. CEL works normal when inside temperature is very hot. If inside temperature is hot or not so hot, CEL won't work. Not the other way around. In other words, if it is related to ECU/ECM temperature, putting ice onto ECM case will not help.
 
  #9  
Old 10-10-15, 06:51 PM
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You right. Read post so many times and still missed it. Then heck number 2. Put heat blower against it. Heat pad or something. Keep it warm.
 
  #10  
Old 10-11-15, 03:15 PM
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I took off instrument cluster, inspect circuit board, light bulb, and they all look good. I switched CEL and battery light bulb. Then, I turn key on to check lights. CEL, battery, and other light come on and work as normal. However, when I put back instrument cluster back to its position and turn key on, CEL doesn't come on, but battery light on and off if I wiggled wire. I now know it is connection problem. I inspected wire and don't see anything obviously cause this problem. Put everything back and all lights work like normal now.
 
  #11  
Old 10-11-15, 04:04 PM
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Khool. Amen and forget about it then.
 
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