mil light stays on cranks no spark

[glenwbl67]

car was running hid wiring harness now no go cranks but that's it.no bcm or anything vs motor in a wb.thanks.

[pman92]

V6 or V8?
Was running fine before in the WB? All you have done is change harness routing to make it look better?
And now no spark?

Do you know if you have injector pulse?
Is the fuel pump running?

Likely a problem with the ignition module wiring you have changed

[antus]

Can you get tunerpro on it and see what the light is trying to tell you? Probably will point you straight to the right circuit.

[pman92]

Isn't the MIL light meant to stay on until it starts?
If it cranks but doesn't start it would stay on.

[glenwbl67]

thanks guys for replys.its vs v6 got injector pulse power at dfi checked pcm with multi m its getting power, earth, signal from cas etc. all I did was move relays and fuses from engine bay to under dash.its an after market harness and its only got 6 wires going to the 2 engine wiring loom connections ,ign, fuel p, tacho, temp, earth for fan relay, efi and ive checked them with test ligt everything seems to be right unless I got 1 of these 6 wires going to engine loom wrong but I have checked them a few times.im not sure if mil light is ment to stay on until engine starts.tps was making weird noise so replaced it.sometimes it seems when you first turn ign on fuel pump runs a lot longer than the 2secs it usually does. don't know much about computers I would have no chance off working tunerpro.is it possible to use tuner pro on after maket harness that's only got 4 wires going to the plug you would connect it to,i forget what its called any ideas greatly appreciated.thanks

[Gareth]

Tps made a wierd noise... WTF?

[pman92]

It couldn't of been the tps making a noise, maybe IAC? Anyway I don't think that's related.

Make 100% sure you have injector pulse. That doesn't mean just power to the injectors, but an earth "pulse" signal as well. Connect a noid light or LED test light across an injector plug and make sure it flashes when you crank it.
Double check you have fuel pressure, pull the pressure line off and make sure it's pressurised.
And double check you have no spark.

Once you've double checked everything, and confirmed you DO have fuel pressure and DO have inject pulse and DO NOT have spark, you need to be looking at the DFI wiring, power earth etc.
The DFI is designed to provide spark at a fixed angle until the engine starts/reaches a certain speed (eg 450rpm) without the PCM/ECU having anything to do with it. In theory (I may be wrong, never actually done it) you can disconnect the PCM and crank the engine over and it will still have spark, but obviously not start as there is no fuel.
The DFI needs a crank angle input and no 'bypass' input (which is what the PCM supplies once the engine starts and the PCM takes control of spark timing) to do this.
If you have injector pulse you have a crank angle sensor that works.
Maybe the power or earth is missing?
Maybe the bypass wiring is wrong?
Maybe the crank angle input is no good? (I don't believe so as I think it goes through the DFI to the PCM)

If you find either:
-You don't actually have injector pulse
-You don't really have fuel pressure, Or
-You actually DO have spark
Then ignore everything I've just said and post back.

[glenwbl67]

thanks heaps pman92 ye ment iac not tps.ill go do what you suggest now got injector pulse checked across plug with t light checked fuel pressure.ill go see if dfi is getting what it should.thanks again pman.changed cas got 5v at pcm but notning at dfi.is it the 18x or 3x and should it be 5v also when ign on

[antus]

18x and 3x will pulse between 0 and 5v more quickly than you can see with a multimeter. If you try to see it on a multimeter you will likely see it as an unstable voltage. Without an oscilloscope to actually inspect the signal a result like this should be considered "probably but not conclusively ok".

With a scope you should see something like the blue line in the "PCM to Dash" image posted for a different reason by vl400 here http://pcmhacking.net/forums/viewtopic. ... 631#p10631 . That is 0 to 5 volt and back per pulse. But the speed of the wave will change with engine RPM.

[glenwbl67]

still wont start got power going to dfi but no spark, no power out of dfi for cas.tried 3 dfi's all same.no cas signal at pcm.pcms got power, earth. thanks antus for help but im no mechanic im a house electrician.i can only check basic things with m meter t light etc.got inj pulse, power at dfi; does this mean pcm's working?im only a beginner this is my first project and ive only used a computer a few times. im shattered it was running fine was booked in for engineers cert had to cancel it cause now it wont start. thanks again