What would stop car from providing spark during cranking?

[XtreemeChaos]

I'm having a crank, no start condition with my car. More detailed info here: http://ls1tech.com/forums/general-maintenance-repairs/1751814-car-cranks-won-t-start-no-spark-what-check-next.html

What signals need to be sent to the IGN relay under the hood to allow the injectors to fire and provide spark?

Other than VATS and crankshaft position sensor, anything else that would prevent car from starting?

[joecar]

What year/model/vehicle...?

Do you have battery voltage at each injector and each ignition coil...?
When cranking, do you see PCM signal at each injector and each ignition coil...?

[XtreemeChaos]

What year/model/vehicle...?

Do you have battery voltage at each injector and each ignition coil...?
When cranking, do you see PCM signal at each injector and each ignition coil...?

It's a 99 trans am.

This is the first time I've had to troubeleshoot electical / wiring issues. Where exactly do I test the injectors and coil? I have confirmed there is no signal during cranking using a noid light. I've placed a multimeter lead down the boot beside both wires going into the injector plug, but am only seeing a negative value on the multimeter.

[5.7ute]

Both injectors & coils use a common power input for each bank. If you do not have power at either with the ign on, start with the fuses & work from there.

[XtreemeChaos]

Both injectors & coils use a common power input for each bank. If you do not have power at either with the ign on, start with the fuses & work from there.

#1 (http://ls1tech.com/forums/general-maintenance-repairs/1751814-car-cranks-won-t-start-no-spark-what-check-next.html#post18469535)
10-10-2014 01:06 PM by XtreemeChaos (http://ls1tech.com/forums/member.php?u=11728)

Looking for a little help here.


http://www.hotrodlane.cc/New%20LS%20...0Not%20Run.htm (http://www.hotrodlane.cc/New%20LS%20Links%20Page/Engine%20Cranks%20but%20Does%20Not%20Run.htm)

Things I've checked per the above guide.

Step 2: No DTCs after letting it crank for 15 seconds.
Step 3: Fuel is enabled per EFILive
Step 4: RPMs show ~150 while cranking in EFILive
Step 5: INJR1, INJR2, ENG CTRL, ENG SEN, and A/C CRUISE (http://ls1tech.com/forums/general-maintenance-repairs/1751814-car-cranks-won-t-start-no-spark-what-check-next.html#) fuses do not have power on either side.

Step 5 links to the Ignition Relay diagnosis, which I can't find anywhere else.

Other steps taken/notes:

Ignition Relay replaced in the fuse box (http://ls1tech.com/forums/general-maintenance-repairs/1751814-car-cranks-won-t-start-no-spark-what-check-next.html#) under the hood.
Fuel pressure is good.
Confirmed no spark by grounding spark plug.
No Injector pulse - tested with noid light.
Security light goes off after key is in ignition and turned on 4-5 seconds.
Re-seated PCM harnesses.
EFILive shows readings for Injector Duty Cycle (http://ls1tech.com/forums/general-maintenance-repairs/1751814-car-cranks-won-t-start-no-spark-what-check-next.html#), Spark, and Commanded A/F ratio.



(http://ls1tech.com/forums/newreply.php?do=newreply&p=18469535)

[XtreemeChaos]

Both injectors & coils use a common power input for each bank. If you do not have power at either with the ign on, start with the fuses & work from there.

Checked the INJR1, INJR2, ENG CTRL, ENG SEN, and A/C CRUISE fuses and they do not have power on either side. I've also swapped and replaced the IGN relay.

[joecar]

It's a 99 trans am.

This is the first time I've had to troubeleshoot electical / wiring issues. Where exactly do I test the injectors and coil? I have confirmed there is no signal during cranking using a noid light. I've placed a multimeter lead down the boot beside both wires going into the injector plug, but am only seeing a negative value on the multimeter.I assume you set your DMM to VDC...

if you don't see the signal from the PCM on any injector and coil, then either there are connector problems in the wiring, or there are ground problems.

Let's see if I can dig up the 1999 F-car No-Start diagnostic chart.

[XtreemeChaos]

I assume you set your DMM to VDC...

if you don't see the signal from the PCM on any injector and coil, then either there are connector problems in the wiring, or there are ground problems.

Let's see if I can dig up the 1999 F-car No-Start diagnostic chart.

Is this the cart you are referencing? http://www.hotrodlane.cc/New%20LS%20Links%20Page/Engine%20Cranks%20but%20Does%20Not%20Run.htm

I followed it down to Step 5, which links to the Ignition Relay Diagnostic, but the link is dead and I can't find any other references to a Ignition Relay Diagnostic.

[XtreemeChaos]

Is this the chart you're referencing? I've made it down to step 5, where it links to an Ignition Relay Diagnostic, but the link is dead and I can't find any other reference to this diagnostic.

http://www.hotrodlane.cc/New%20LS%20Links%20Page/Engine%20Cranks%20but%20Does%20Not%20Run.htm

[joecar]

Is this the chart you're referencing? I've made it down to step 5, where it links to an Ignition Relay Diagnostic, but the link is dead and I can't find any other reference to this diagnostic.

http://www.hotrodlane.cc/New%20LS%20Links%20Page/Engine%20Cranks%20but%20Does%20Not%20Run.htm

In the attached zip, locate the diagram showing the ignition relay, and check that the relay has voltage, and that it gets signal... also check that the relay socket terminals are making good contact (not loose).

[samh_08]

Check your grounds on the block, should be a couple of them forsure. Clean, tight, and actually connected :).

[XtreemeChaos]

In the attached zip, locate the diagram showing the ignition relay, and check that the relay has voltage, and that it gets signal... also check that the relay socket terminals are making good contact (not loose).


Thanks for posting this. I may not be looking at these right, but I can't seem to find the ignition relay diagram. I see references to "Hot with Ignition Relay Energized", but I can't find the diagram to see how it gets energized. I have confirmed that each of the fuses that state "Hot with Ignition Relay Energized" are not getting power.

[joecar]

Thanks for posting this. I may not be looking at these right, but I can't seem to find the ignition relay diagram. I see references to "Hot with Ignition Relay Energized", but I can't find the diagram to see how it gets energized. I have confirmed that each of the fuses that state "Hot with Ignition Relay Energized" are not getting power.Ah, sorry, my apologies, I meant to include this also (attached)...

see D.gif for the ignition relay.

[Lil Mack]

Any update on this? I have a similar problem and wonder if this was resolved.

[Lil Mack]

I have solved my no spark when cranking issue.

My setup is in a swap, l92 454 on 0411 pcm. It would pop a few times and stop sparking. I found that the ignition wire had been moved in the fuse block. It was hot when key on but not when cranking. So the coil would charge up in the run position and loose 12vdc when in the start position. I moved the ignition wire to a terminal that is hot when in run and start. Now she starts every time.