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I believe even more common is micro-cracks in the solder on the PGM-FI main relay, which usually manifest as the symptoms you described. My 1997 Civic used to do this intermittently, though almost predictably, during long exposure to very hot weather. Eric has a video somewhere about this, or just search “Honda” “main relay” in youtube where several videos discuss how to fix it yourself.
It looks to me a lot like the PGM-FI main relay issue that is common on Hondas. Not sure of course, but there’s where I’d put my money.
The PGM-FI main relay provides power to several components including fuel pump, fuel injectors, and ECU. When the main relay circuit board develops micro-cracks in its solder due to temperature changes expanding and contracting the main board, it creates temporary, even permanent breaks in the solder. Depending on which solder has that micro-crack you may lose power to any of those 3 components. There are various symptoms but most appear to be intermittent and are either outside temperature related and/or happens when the engine is restarted soon after being turned off. Given enough repeated cranks the engine will eventually start (probably due to electricity arcing across the cracked solder then heat “healing” the cracked solder, thereby fixing it until it happens again).
I believe one of Eric’s videos identifies it as one of the most common suspects when faced with a no start problem on a Honda (assuming battery’s ok).
The same thing has happened maybe 4 times in the last two years to my 97 Civic but only when driving in very hot weather. When my trusted mechanic was fixing something else on my car I told him about it and he pulled out the PGM-FI main relay to show me the micro-cracks in one specific solder that was causing it. Unfortunately we didn’t have a soldering iron handy at the time so we didn’t get to fix it but will do it myself soon.
Just search youtube and Eric’s videos as there are many videos there showing how to fix it. You just need a soldering gun and maybe some lead. Hardest part is actually taking out the relay in some instances but even that’s not so bad.
It’s all the time
What’s all the time? The light or the switch signal? Was the light still on after unplugging the brake light switch connections?
It seems your car’s brake light switch has two, separate connectors — would that be because the 3rd brake light is separately wired from the other brake lights? If so that might be a clue to what’s going on — maybe check the output of the brake light switch if one of them is permanently on. Lacking any wiring diagram, check to see which wiring colors between the brake light switch and the 3rd brake light match to confirm which connector goes where.
[quote=”chowceal” post=186805]on the voltage drop test, ignition needs to be disabled. is this as simple as pulling a relay?[/quote]
Simplest way would be to remove the fuel pump relay or fuse.
Here’s a nice document on voltage drop testing the starter, as well as charging circuits.
The PCM is probably not the first place to look (very likely the last!). Check the basics first — battery and starter. Typically you’ll need to set your multimeter on the 20V setting DC to check for battery voltage at the battery posts as well as where the charge needs to go to get your engine started. You may want to watch this video as a guide:
Watch the video in its entirety — the part about voltage drop tests is also important. Probably just skip the parts first that need specialized tools (battery load test) — if your car starts sometimes I doubt your battery’s the problem.
It seems to me your battery to starter connection has intermittent problems (loose somewhere? bad/corroded cables? intermittent relay?), but you really need to test one-by-one to rule out each component, starting with the battery and starter. You’ll need someone to help you turn the ignition while you check for battery voltage on the wire going to your starter solenoid.
Good luck!
You may want to get one of those OBD2 Bluetooth dongles that work with a smartphone app in logging and monitoring OBD2 data so that you get at least some information saved if it does happen again. It may or may not capture the specific info you need, but at least you’ll have something.
I have no experience with them so I wouldn’t know which specific dongle and app pair to recommend but among apps Torque Pro seems to be the most popular. Maybe just get recommendations from the Torque Pro users which Bluetooth dongle works best.
I had the exact same problem for the longest time (years!) on my car (Civic VTEC 1.6L 1997, 120K Km). It wasn’t fixed by new transmission fluid, it wasn’t fixed by a transmission cleaning and overhaul, but recently it got fixed but since I did a couple of things I’m not sure which one fixed it:
1. I readjusted my throttle cable to be more taut, since I noticed it had play outside of the recommended specs (my transmission also has a connected kickdown cable but I did not readjust it).
2. I stopped my habit of shifting to neutral when at traffic lights (I developed this habit when my car had (unknown at that time) grounding problems which caused my RPM to drop when I was at stops stepping on the brakes on Drive) since I learned this was bad.
3. My ECU was reset (inadvertently) when I was removing fuses to troubleshoot a no-start condition after I accidentally drained my battery.This all happened within two weeks of each other and I noticed that since these events, my harsh shifting from 1>2 disappeared. It’s still there to a smaller degree when the car does its first shift after a cold start but as soon as I get to do it the second or third 1>2 shift it’s gone.
So again, I’m not sure which fixed it, but if I had to guess it was mostly #3 because that’s the last thing that happened before I started noticing the change. Maybe with the help of #1 & #2.
Just putting it out there in case that helps.
[quote=”ashystyle” post=186195]Did my own battery load test. The battery did not went lower than 10.5v during the start of the engine.
Have not done any other battery tests.
I will have to do the alternator test. But since the alternator sits very badly hidden.. its kind of hard to get to it and its terminals.
Is there any video showing where all the power and ground connections are on the Jeep Cherokee XJ 1995?Thanks![/quote]
If it’s hard to do an alternator test on your vehicle just try checking your battery voltage with a volt meter each time after a regular drive. Give it a few hours after driving before you measure the battery voltage. You should be measuring more or less 12.6 volts with a good battery. Lower than 12.4 then your battery or charging system is suspect.
Another quick test to see if your battery is charging is to run the engine and see what the charging voltage is. It should be around 13.8-14.5 volts. Then turn off the engine and right at that moment you should see 13.2 volts, which would then drop rapidly then very slowly settle to around 12.6 volts (position your volt meter so you see it through your windshield as you turn the ignition off). If you see 13.2 volts or higher right at the moment you turn the engine off it’s a sign that the battery was charging.
If you don’t see these numbers then move on to your alternator to test the charging circuit. Do voltage drop tests on both the positive and negative sides. Sometimes wires may look good and clean but may have unseen damage or corrosion that’s causing high resistance which only a voltage drop test can show. Ideally the voltage drop on the positive should be no greater than 0.2V and no higher than 0.1V on the negative.
Also do a voltage drop test from your battery negative to the chassis ground, as well as other locations such as the engine block to battery negative. Turn on most of the electricals like headlights, A/C, and radio when doing this. If you see a result higher than 0.1V drop on the ground side then you have a bad main engine or chassis ground connection somewhere. In my experience a drop of 0.2V on the ground side results in a very obvious inability for the battery to charge properly especially at idle.
There’s only one wire to it, right? I believe it’s the optional fog light connector. There should be one on the other side as well.
There are two cooling fan (ECT) switches — A & B. Are they OEM? I suspect one of them is either not switching or is switching at the wrong temperature. You should probably test both.
There’s an Accord service manual here. Check out the test for Fan Controls bit in section 23. The two switches have different specs and are supposed to engage at different temps. There are further tests in section 22 of the units shared with the A/C.
Are you sure that the radiator fan is running (and not just the condenser fan) when you observe the temperature not going down at a stop? If so then (this might be a stupid question) is the radiator fan blowing in the right direction (towards the engine)? If so then is it blowing air fast enough? That might be hard to verify unless you compare it to another similar Accord with a working radiator fan using a wind speed gauge, unless there is a dramatic difference.
If all of the above are in working order then the next suspect is the radiator fan control module.
I used to experience that on my ’97 Civic AT. Turned out to be bad battery and engine grounds (do a voltage drop test).
RPM drop was more pronounced at stops because of the load on the alternator from the brake lights. I have the 75amp stock alternator so there wasn’t much room for bad electrical connections. The random drops may be due to some high amperage electrical device that periodically turns on and off, such as A/C clutch or radiator/condenser fan.
I don’t know that cleaning the FITV alone would necessarily work. The valve itself might be faulty and no amount of cleaning will fix it.
Have you seen this one? http://www.hondaaccordforum.com/forum/do-yourself-section-26/fitv-cleaning-28486/
If you haven’t yet, try to do steps 1-3 in that article to see if your FITV is working properly after the cleaning. You’ll need to feel if there’s suction going to the FITV even after warm up. If there is then it’s not working. There are further steps there in that article that show how to try to fix it if you’ve verified it’s not working. If none of them work it’ll have to be replaced.
At this point I’d say the FITV is still your #1 suspect as it’s also consistent with your other symptoms. Your engine is running lean and might explain the overheat you experienced when the engine was under heavier load (carrying heavy stuff uphill). Your engine continues to run lean so I’d avoid using it too much if possible until you find the fix.
Might be a good idea to do tests on the head gasket after you’ve fixed the surging problem just to make sure. The earlier you catch a blown head gasket the better. I learned this lesson the hard way and eventually had to replace my engine after a few years since the initial failure. Since then I’ve installed a coolant temperature gauge with an alarm that beeps when the temps go into dangerous levels.
Does your service manual have the electrical wiring diagram of the various systems? If so trace the path that the failing components take and note the connector(s) that is (are) common to them, if any. That’s where I would start checking. For example, based on some wiring diagrams on the Internet, the headlights and the right sliding door on the Odyssey both go through the C203 connector. I don’t have the service manual so I don’t know where that connector might be but based on Honda numbering convention it would be somewhere under the hood. Backprobing the wires in the connectors that power those failing components with a volt meter would be essential in finding the fault to find at what point the circuit loses battery power.
Can’t say how work on the dash would’ve affected under hood wiring but at this point you probably have to expand your area of search.