94 Accord Intermittent No Start

start

#1

94 Accord intermittently won’t start and throws a Code 15. I clear the code, but it is always a code 15 that it throws when this problem occurs. The engine sounds as though it’s starting and actually catches up with the starter so you hear the flywheel grind indicating that the engine is firing well enough to turn faster than the start. Then, when you let go of the key, it shuts down. Usually when sitting in sun when cabin is hot, but occassionally happens when cab is not hot. This problem is NOT related to engine being hot. About 5 or 10 minutes after opening windows and doors the car will start, as though something in the cabin is cooling down. I have replaced the ignitor and the ignition switch and reflowed the cold solder joints on the PGM-FI relay. I also had my daughter remove the PGM-FI relay and take it into class with her, then plug it back in when she was ready to leave and she still experienced the no start condition until the cabin cooled for 5 or 10 minutes, so that ruled out the relay getting too hot. I’ve wiggled and jiggled every connector I can find and brushed and cleaned the battery terminals and all the grounding straps I can find under the hood. Fuel pump runs fine and supplies plenty of pressure and there IS spark and compression when the no start condition is occurs. Any ideas would be appreciated! Thank you! Jim


#2

Whatever you do,DON’T go to this web site looking for answers: www.tegger.com/hondafaq/startproblems.html---it’s too much reading.


#3

You’ve reflowed the solder on the main relay but it’s entirely possible the relay could have a fault internally; more than likely a burnt set of contact points.

I believe if the vehicle were mine I would replace that relay with a new one. The same heat (caused by current draw) that does the solder in is also simultaneously cooking the contact points.


#4

Do you know if a code 15 is typically associated with the relay failure. I haven’t been able to find anyone yet who can say they’ve seen that association. I also felt like I ruled out the relay when my daughter took it into class with her. Thanks!


#5

The Diagnostic Trouble Code (DTC) 15 is the engine computer telling you that it hurts in the Ignition Output Signal area. It’s possibly a faulty igniter. Ways to check the igniter, and ignition coil, are at: http://www.tegger.com/hondafaq/startproblems.html#badigniter. If you are willing to do the appropriate tests, you can get a good fix done to it.


#6

Well, you have compression and a spark so that leaves a fuel supply problem.

During a no-start, try running a jumper wire from the red/white wire at the main relay to the black/yellow. If the vehicle starts and runs then you know the problem is either the main relay or the relay controls (in the ECM).

Since you’ve replaced the igniter about all I could suggest is to verify that the ECM is getting an electrical pulse from that igniter. It should be the yellow/green wire between the igniter and terminal A21 of the ECM according to the schematic.
In theory, lack of a pulse through that wire/connectors is the source of the DTC 15, but…

Also make sure power is provided through the black/green wire when the ignition switch is turned to the START position only.

There’s other tracing to be done here but I hate to overload it at this point.
I’m still not sold on relay removal and cooling it in a building. That’s a coin flip type of thing IMHO.


#7

ok4450,

I was tracing that yellow/green wire the other day from the ICM and lost it shortly after it went through the firewall on the driver’s side (that confused me since I thought it would enter the firewall on the passenger side). I’m feeling like I have a bad/intermittent connection associated with that somewhere within the cab, but may Haynes manual doesn’t give me enough details to trace out that wire very well. Can you provide more details as to exaclty which is terminal A21 on the ECM? I’d like to have my scope on that connector when the no-start condition occurs. I think you’re saying the signal on that yellow/green wire is ‘from’ the ignitor ‘to’ the ecm??? I was thinking it was ‘from’ the ecm ‘to’ the ignitor.
If you can help me I.D. connector & pin A21 I that would help me trace out that wire for continuity when I’m experiencing problems. I could also snug up that pin a bit as well. I should mention that when I’ve had the trouble before, I disconnected the fuel rail and had LOTS of fuel pressure. Problem is, every time I’m troubleshooting, the car suddenly begins working. The ONLY thing that is consistent is that I’ve opened the doors and windows while troubleshooting and after the cabin cools for about 5 or 10 minutes, the car ALWAYS begins to work. I also can’t find anyone who has ever associated the PGM-FI relay with code 15, so that keeps steering me away from that. This problem is sooooo intermittent it’s a real stumper so far. That A21 conn/pin is my target now. Thanks a bunch!!!


#8

I do not have a diagram of the pin layout on the ECM but according to the schematic I have (Chiltons, always a toss-up as to believeability) shows this yellow/green wire going directly from the ignitor to the ECM.
I would go into the harness next to the ECM and check the wire at that location.
Of course, if the problem is actually the tiny pin connector then that would be a lot harder to figure out.
In the event that the pin could be scaled over it’s possible that simply disconnecting the ECM connector and plugging it back in could clear the problem up.

The main relay is controlled by the ECM and the module/ignitor/whatever provides an ignition pulse to the ECM. This is what tells the ECM to electronically close the circuit in the main relay and activate the pump along with powering the ECM up.
The ECM is basically being told that the engine is turning over and the secondary ignition is working.

Cars are designed like this so they will conform to Federal law that require the pump stop operating when the engine quits during a collision, etc.

Since the ECM is also powered by the main relay my concern was that a faulty set of points in that relay (there are 2 sets, one for the pump, one for the ECM) could be causing the ECM to go stupid and give you that code 15.


#9

Gotcha! I really appreciate your help! I’ll continue to explore with that in mind. Your explanation has provided some clarity to me regarding the relay theory. If I am able to nail it down, I’ll repost with my findings! Again, thanks for your good explanations and patience! Jim