No Spark

[kstigler]

Do you have an immobilizer light on the dash or anything during cranking? does the car have immobilizer?

Have you checked the relays?

Not sure what an immobilized light is?

I have checked fuses but not relays.


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[avguy]

So... how does having the top timing belt cover off help? I can see if the two top pulleys are in time. How does that help me with the lower crankshaft timing validation? ...

It's simply a quick test to validate that the belt is in good condition (no teeth missing, etc), and that the belt loop motion is consistent and smooth as the engine cranks. It doesn't completely rule out a timing belt loop issue, but a visual check that looks good does make that a far less likely possibility. If there is any doubt, a compression test can be done for additional diagnosis.

Again, I'm not telling you this is the cause of your no-start, only that it's quick and easy to get a good, basic evaluation of the condition of the belt loop.

[kstigler]

What about other sensors? Like coolant sensor, etc? Would those shut down an engine?


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[avguy]

I don't think any sensor except the crank would result in no spark at all. Have you tried to see if the injectors are working? They're on a different circuit from the coils, and would provide additional diagnostic information if they're working (or also if they're not).

[kstigler]

I don't think any sensor except the crank would result in no spark at all. Have you tried to see if the injectors are working? They're on a different circuit from the coils, and would provide additional diagnostic information if they're working (or also if they're not).

I am guessing that the injectors are also not working.. no gas smell when cranking the engine.. I would expect some gas to escape through the combustion system out the exhaust..

How can I verify an injector is working? Can I pull one out and plug the cable in and turn the engine?

[kstigler]

So.. I found a schematic for the power distribution for this car.. I found the "Main Relay" that, according to the schematics, supplies power to the fuel injectors and a series of other components.. according to the schematics, I should have a constant 12V at the coil and one side of the contacts, and the coil circuit is "made" by the ECM grounding the Main Relay coil. Ok.. I am testing voltages.. i have 12 volts at the contacts but not at the coil.. OK! sounds like I am on to something.. no fuses between the coil and the battery.. so, I suppose it's time to pull the fuse box out from under the hood, and take a look at the wiring.. I pull the battery, disconnect the fuse box, flip it over and start tracing wires.. hold on.. there is a factory wiring jumper around the contacts on the relay! The relay is useless.. doesn't matter if the coil is hot or not, the contacts have a jumper around them.. hmm.. so I put everything back and start checking voltages.. sure enough, there is 12 volts at the fuel injectors at all times. not just when the main relay is energized.. so what the? the relay is useless, it's installed for no reason since there is a factory jumper around it.. sigh..

still can't start the car, still no spark

Schematic in question attached..

[avguy]

If I'm reading your last reply correctly, the only thing you did was to confirm that the injectors are getting voltage. But, as the wiring diagram shows, the ECM supplies ground to complete the circuit and fire them. Did you confirm that they are (or are not) getting ground and firing? How about the testing of the wires coming into coil pack - what did those results show? Also, you previously posted that you 'metered' the crank sensor. Was that done using a multimeter or a scope?

[kstigler]

If I'm reading your last reply correctly, the only thing you did was to confirm that the injectors are getting voltage. But, as the wiring diagram shows, the ECM supplies ground to complete the circuit and fire them. Did you confirm that they are (or are not) getting ground and firing? How about the testing of the wires coming into coil pack - what did those results show? Also, you previously posted that you 'metered' the crank sensor. Was that done using a multimeter or a scope?

I replaced the crankshaft and camshaft sensor.. I also have a friend that works at a junkyard, so I picked up an ECM from another Aveo just to see if mine was dead. no change.

What I don't see, is when I am cranking the car, the tach does not indicate any engine movement at all.. I don't even see the 200+ RPM from the starter turning the engine

I have not tested the wires to the coil pack.. that is on my list and I was looking for that wiring diagram when I ran into he main relay diagram

[RexSmith]

I contacted the OP offline - and he mentioned to me that for him - the fix was that an under-hood fuse labeled DIS (10A) had been blown. He replaced it and that fixed his problems. (My problems are on another labeled circuit - and in another thread here on the forums)