1994 Accord MPFI with intermitent no start. Main relay is operating fuel pump. Ignition system is providing spark during no start. Checked connectors C131 and C124. Tested pins B11/12, 13/14, 15/16 @pcm all readings of 360 ohms (testing TDC/CKP/CYP sensors and circuits). No continuity from these pins to ground. No check engine light on. Question#1: When performing flash codes, is the check engine light suppose to flash or the green D4 shift indicator? Indicator lamp is flashing codes 1, 8, and 13. Question#2: Am I correct in suspecting a bad PCM (ecu)? Anything else I need to test? Thank you in advance for any responses.

 

Check Fuel injectors. If you have the right equipment you can do a leakdown test. Ive come upon many earlier model hondas with bad injectors.

 

Both lights can flash if there are codes pertaining to both systems, the engine and trans. Just to be sure here you are saying that the D4 light is the only light giving you all three of these codes?

8 on the trans is a shift solenoid code, on the engine it will need another distributor. Testing for ohms is no longer a preferred method, having an oscilloscope is, but of course most folks cant afford one so out comes the multimeter.

Clear the codes and see what comes back, thanks for getting them in the first place. Honda ECU's are pretty reliable, but not bulletproof.

 

Yes, it is the shift indicator flashing, not the check engine light. So these are transmission codes, not powertrain? I do have access to an oscilloscope and will check patterns. With a remanufactured distributor in the $300.00 range, how do you feel my chances are with a used unit should this be the fault?

 

Once again my friend, clear the codes and see what comes back immedietely and after a few drives. For example, if the D4 light was flashing for a VSS, it is also possible for the engine ECU to store a code for the VSS also. I do not have TCM trouble codes other than this one I gave you, sorry. Dont get a distributor without the CEL flashing the code 8.

I would say that the TCM is only checking for a circuit continuity test on the shift solenoids and wiring, does the car shift normally. If so then it may be an intermittent problem, maybe just a bad connection or corrosion. I do not think that there is a logic test to see if the solenoid actually worked???

 

To get back to the original inquiry, vehicle is showing no transmission issues. Intermitent no start. Had it towed due to the no start. After delivery off the rollback, started for 2 days then finally had it's no start where I performed previously mentioned tests from troubleshoot guide which pointed to cylinder position sensor or pcm (ecu). With no code flash from amber check engine light, this is why I am leaning towards pcm. I will check scope pattern of sensor.

 

If you indeed have a bad distributor or ECU, then if the internal sensor is acting up then I would think that you would be missing either fuel injection or spark during your no start condition, can you please verify that you have fuel injection and spark with your no start.

If you have all good signals going to the ECU, of proper (minimal) amplitude then you have spark and fuel injection, then I would think the ECU is good, more to come though. Do you know how to post pics?

 

As stated, when no start was occuring, spark was available. Today, the vehicle decided to start. I don't like throwing parts at a problem, but I did install a used pcm and will see what happens the next several days.