PistonRings

Hi guys

I'm working on an old 1997 Honda CR-V that's not getting a spark.

I've replaced the complete distributor, ignitior, coil ,cap and rotor.

I've tested all the wires and in not getting any pulses from them when the engine is cranked.


if I probe the yellow/green signal wire using a earthed test light I get a pulse from the coil.

so it seems that the ECU isn't sending the pulses signal to the ignitor.

So my question is, what sends a signal to the ECU telling it to send the pulsed signal from the ECU to the ignitor using the yellow/green wire?

thank for any help given

Txdragon

Bad ecu it sounds like.

PistonRings

thanks for the reply

that's what I'm thinking

do you know what tells the ECU to send the pulse down the yellow/green wire?

I'm guessing it's one of the sensors in the distributor (3 black magnetic sensors).

Txdragon

The yellow/green wire you're probing.. Is it the female plug? You're probing with key on position 2? Or you probing the yellow/green in the distributor?

motoxxxman

The yellow/green wire is the signal wire to the igniter, it is the ecu signal. So if that is pulsing, then the ecu is fine, because the pulse is coming from the ecu.
Test the blue wire from the Igniter, that is the tach signal output wire from the igniter, which would be a signal after the igniter. If you do not get a pulse on the blue wire, then either the igniter is bad, or not grounded properly, or there's an electrical issue somewhere between where you probed the yl/grn wire and the igniter. If you do get a pulse on the blue wire, but still no spark, It could still be a ground issue, or bad coil, or bad connection between igniter and coil. Or no power to the coil.
Check fuse #9 in the under dash fusebox. Check for battery voltage at the yellow/black wire going to the coil.

PistonRings

thanks for the reply

it's as motoxxxman said, it's the yellow/green wire that goes from the ECU to the ignitor.

PistonRings

Thanks for the reply

I realise the yellow/green wire is the signal wire, but it's not pulsing on its own and only pulses if I manually probe it.

That s why I asked what triggers the ECU to pulse the yellow/green wire as that could be the fault?

the no9 fuse am yellow/black wire all test out ok.

it just seems that for some reason the ECU isn't pulsing the yellow/green wire.

motoxxxman

Ah ok, I read your post wrong then.
All 3 sensors in the distributor contribute to the ecu sending the signal out the yellow/green wire. Check continuity to ecu for them all.
Also, remove the distributor and look inside at the end of the cam while somebody cranks the motor. Make sure the cam is actually spinning. If it isn't; either the timing belt broke, or the camshaft broke.

motoxxxman

Also, that car has a recall on the ignition switch, which could be the cause of the problem. The symptom is described as the car stalling while running, or not starting while cranking.; due to faulty contacts in the ignition switch. The dealer will replace the ignition switch for free.

Txdragon

Bad ignition switch will cause no fuel and no spark if faulty. If spark is the only thing missing, I don' believe ignition switch is the culprit.

Txdragon

Time to kill a rat with a 12 guage... Tap ECU pin A21 and run that wire direct to your yellow/green wire at the dizzy. Kinda bridge it, bypassing the bullshit in the harness.. If you still don't have spark, replace ECU..

Edit: The ECU is the boss. Nothing tells it what to do, it tells the engine what to do. It sends signals based on input received from sensors. If it's not sending a signal, it's either not getting input or broken. Your dizzy will not send a signal to the ecu, so of your dizzy is not getting a signal, it's wiring or ecu.

PistonRings

Thanks for all the replies guys
sorry I didn't receive a notification about any replies and just came on here to say a few more things I've tried.


Yesterday i checked the resistance on all three sensors I the distributor and they all checked out ok.

I also checked continuity between the wires from the distributor to the ECU and they also checked out.

all earths on the ECU are ok.

I then put a tester on the injector plugs and I'm not getting any pulses on the injectors either.

I can hear the fuel pump prime when I turn the ignition on.
what do you guys think?

motoxxxman

I think you have a bad ignition switch. Free replacement at the dealership.

It may or may not work, but worth a try to see if ignition switch is in fact bad:
Turn ignition on, make sure CEL comes on for 2 seconds than turns off, which is what happens as the fuel pump primes. After that, do not touch the key, leave it as is. Make sure tranny is in park if it's auto, or neutral if it's manual. Grab a wire a couple feet long. Hold one end on the starter trigger terminal, then touch the other end to battery positive. Essentially jumping the starter. The engine will crank. See if it has spark or injector pulse while doing this. Or if fully assembled, see if it starts. Don't be afraid of sparks when touching the battery, it won't hurt you.
Reason I say hold the wire to the starter trigger terminal first, or better yet use an alligator clip to hold the wire to the terminal, is because you don't want to short the wire out on anything as you bring it down to the starter which can happen if you attach the wire to the battery first and touch to the terminal.

PistonRings

Thanks I'll give that a go and report back

I have a power probe so I can just turn on the ignition and then use the power probe to send the 12v to the starter trigger

PistonRings

Just thinking. ..

wouldn't that test only test the wire to the starter motor?

if so then my one should be ok as the starter motor works spins as it shouldon the key?

also is there a test I can do on the ignition switch wires?

all the tests and pinouts I find are for a single plug switch and my one has two plugs

Thanks again

PistonRings

I did the test.

I turned the ignition to 2 and activated the starter motor with my power probe and there was a very dull pulse from the coil but then the battery died, so I hooked up a booster to the battery and now I can't get it to pulse anymore


I also checked the wires on the 2 plugs coming from the ignition switch.
One plug had 3 wires and the other plug has 2 wires.

with the ignition in position 2 I'm getting 4 12v and one ground (I think the ground turns to 12v when the starter is activated).


any more ideas?

thanks again for all the help so far

motoxxxman

yes, the one that was ground is for starter. The other 4 are: Battery power, accessory, and two ignition wires.
Disconnect the starter trigger wire from the starter. Check the same 6 wires again with the key held in the crank position. Also slowly rock the key between 2 and crank and see what happens. You should have power on 4 wires and nothing on one wire. But that one wire will be different than position 2; accessory power drops while cranking, but there should be power on the battery wire, both ignition wires, and the starter wire.

PistonRings

thanks again

I did the test and everything checks out ok.

I've noticed that I can't hear the fuel pump prime (maybe it hasn't from the start).

that would lead me to the main relay bit that wouldn't explain the no spark would it ?

PistonRings

Anyone else ?

motoxxxman

could be main relay, or could be ignition switch.
Did you re-test the ignition switch the way I mentioned above for cranking?

PistonRings

yes I did your test and the switch seems to be working.

I didn't think the main relay would stop it sparking ?

PistonRings

Is it possible for the main relay to stop it from sparking ?

motoxxxman

the main relay controls power to the fuel pump, ecu, injectors, and idle valve.
So yes, it could cause a no-spark if it's not sending power to the ecu correctly.