View Full Version : Need expert help..Crank, no start, no spark.
09-04-2011, 11:23 PM
Heres the problem. Randomly one day without warning car cranks like crazy but does not start. No power to spark plugs.
Does have code P0327 for knock sensor voltage low, but has been there for a few months.
Everything I have checked / tried:
- Checked all fuses
- Fuel pressure about 52 PSI
- Used starting fluid and no change
- No spark at all three coil packs
- Resistance is about 6k in each coil pack
- AC voltage in 7x crank sensor was between 170-270 mV at module plug.
- Replaced crank sensor and getting a more consistent 180-190 mV
- Ignition module power harness receiving battery voltage and ground is good.
- No trigger signal from module when cranking and using test light.
- Replaced PCM, have two programmed for my car.
- Had ignition control module tested at Oriellys and passed tests.
Im lost on why im still receiving no power to the coil packs. Everything leads me to the module but it was checked. Could it still be bad?
Can the 24x crank sensor or cam sensor prevent a start? I know the 7x crank is directly connected to the module and the other two give the PCM signals for the module. Any other sensors that can prevent the coils from working? Is the crank sensor voltage too low and possible caused by the wire?
There is another four pin connector for the icm with 3x ref signals, IC and bypass control. Any idea what these wires should be measuring for voltage?
Any ideas? Thanks!
09-04-2011, 11:28 PM
Couldn't hurt to have the three coils checked out...
09-04-2011, 11:33 PM
Could all three go bad at once? If one goes bad can this prevent the whole system from firing? Their each showing resistance but I don't know how else to check them. Even then the module is not triggering any signal to the coil packs.
09-04-2011, 11:58 PM
A broken timing chain would cause a crank but no start issue!! Hope that's not the case for you as it would be a crummy job to replace the chain.
I had ONE of my coil packs go bad once. It was just one cylinder that wouldn't fire. Had a misfire code on the OBD2 reader. However, it would still start and run just on 5 cylinders.
You can check the coil packs with a voltameter. Pull off the plug wires. Hold one positive wire from the volt meter to one of the coil towers. While placing the negative wire to the adjacent coil tower. A good coil will give your meter a reading. A bad coil will show no response on the meter. A reading would indicate that your coils are fine
Like I said, you can check the packs but dollars to donuts they are fine
How did you check for no spark? Cylinder by cylinder?
09-05-2011, 01:59 AM
My ICM tested fine but when replaced with another my car ran perfect. Just saying
09-05-2011, 03:35 PM
Timing chain is good, valves move when cranking. There is no power to any coil, but like I said the module is not triggering from the terminals to the coil packs.
I first checked for spark by just pulling off the two plugs on a coil and cranking, no spark. Pulled off the coils and checked the module for triggering at the terminals with a test light, no voltage going to the coils.
Its gotta be the module or something the ICM uses to fire spark. I would hate to go buy a new module if the old one is testing good and then nothing changes.
I read before the 7x crank sensor should be outputting a minimum of 200 mV and my first one was jumping between about 170-270mv and the one I just put in is staying around 180mv when cranking. Maybe this harness is bad? Anyone know more about the crank sensor output or the 4 pin ICM harness connector?
09-05-2011, 08:40 PM
I replaced the ignition control module, I was able to get the warranty on it and upgraded to the more expensive one. Same thing, no spark.
Still getting less than 200 mV from 7x crank sensor which is under spec. Tomorrow Im going to test the sensor right at the source and bypass the circuit. This will be easy thanks to the external crank trigger on my 3500.
With a scan tool I noticed the following:
- On one cranking attempt, RPM displayed about 150 RPM during the 5 secs then on the next two attempts couple mins later, 0 RPMS while cranking.
- Timing advancement is 0 degrees while cranking.
Are these specs normal? Im sure I should be seeing RPM and maybe higher and possibly timing advancement. I cant remember exactly, does anyone know which sensors send inputs to the PCM?
09-05-2011, 10:31 PM
You won't get any timing advance during cranking. That's when the engine is operating at base spark which is programmed into the ICM.
The fact that you got 0 engine RPM during two cranking attempts says to me that you need a new 7x crank sensor.
With the 3500 swap I would check the wire between the 7x on the trigger and the ICM. If it isn't routed properly it will like to melt on to something and possibly short.
09-08-2011, 08:53 PM
So I figured out why there was no spark, 7x crank sensor wire was bad. I figured I would just replace it. Made my own and now I have spark and RPM on the data logger. But now its still not starting.
I did replace the crank sensor and i've heard about the case learn. Should the car still start or will this completely prevent it from starting? If I put my old one back in at this point would it make a difference?
09-11-2011, 10:08 PM
I figured out what it was the other day. New crank sensor was bad! Did AC voltage tests resulting in an avg of 30mV. Replaced with old sensor and received around 330mV.
Old sensor and new wire is what fixed it. Thanks everyone for the input.
09-12-2011, 04:34 PM
Good to hear. I just looked at this and was thinking it's got to be something with the 7x or cam sensor. Those are the main two that control spark and injector firing. All three of those (including the 24x crank sensor) actually go through the ign control module to the PCM. The loss of the 24x signal is not that critical and it would still start. The loss of the cam signal will affect injector firing but it can still start if the timing is correct from last start up. The loss of the 7x will hurt it the most though. Luckily the 7x sensor harness is basically just a couple wires by itself, so you don't have to unwrap a big bundle of wire harness to get to it. It just runs back behind the engine which can be a PITA to reach. I'm surprised you didn't have any other codes in the PCM though. Usually if any one of those three is missing it immediately sets a code.
09-12-2011, 05:14 PM
Thanks Aaron. I wonder if its because the wire was getting bad but it still was receiving a small signal that it didn't throw a code vs no signal at all even though it was way off spec. Then again with my car nothing ever did make much sense.
02-20-2013, 01:08 PM
I am having the same problem with a 2000 grand am with the 3400 engine. I have replaced the crank and cam shaft position sensor's. It is getting fuel, the Ignition control module test good over 12 times, new plugs, wires, and i have a 6 different coil packs but no real way to test them. but still no spark at all. And the ecu was reflashed from the dealer.(there is not a security code as far as i know of) Any ideas what else it could be??
02-20-2013, 02:55 PM
Check the AC voltage coming from the 7x crank position sensor, that guy sends the signal to the ignition control module when to fire. If the wire is bad you will find out by the AC output. That wire wraps up the backside of the engine to the module so if it was like mine, looked good but probably fried on the inside from all the heat over the years. I just went to the junkyard and grabbed one myself for a $1. Dealer wanted like $60 for the wire and plug.
02-26-2013, 12:04 AM
Thats the thing I have a good crank signal and a new cam shaft position signal. Ok i installed the new ICM and yet nothing at all.... THe only thing left to change would be the wiring harness. as far as i know of. Anything else that you can think of??
1 checked fuses
2 checked ODB 2 meter
3 fixed anything that has come up the cam shaft position sensor, ICM, spark plugs, plug wires, fuses and a new reflashed Engine computer.
4 checked if its getting fuel
5 Checked it if had spark
Has fuel, power, good plugs, good timing chain and good sensor signals.
NO spark what so ever it has power going in but not coming out...
Anything esle at all??
02-26-2013, 10:24 AM
If its anything like mine there an issue I did not expect. I knew I was getting no spark and the the 7x crank sensor was giving me the incorrect AC output so I replaced it. Still had nothing so I replaced the wire and still was far under spec for AC output so I kept the new wire in and put the old crank sensor in and then it worked perfect. The new sensor was garbage and the whole time it was just the wire but I was tricked by just assuming the new sensor was working.
Have you double checked the wire as far as resistance and AC voltage output? I don't remember off the top of my head but I believe I was only getting like 30mv with the new wire and new crank sensor but then got 330mv with the new wire and old sensor. Just makes sense for your issue to be along those lines if you are getting no spark from any cylinder. Has to be something controlling the ignition control module. And any part in that sensitive 7x crank sensor wiring system will definitely give you no spark.
03-10-2013, 07:39 PM
Ok have the ICM fuse blown so i replaced it and it still does the same thing. No spark, no start but it cranks like crazy. Anyone with an Idea on how to read codes?? when i turn it over the lights all come on like normal b ut after i quit the battery light comes on the seat belt light comes on like usual and the oil light flashes exactly 7 times, on the fifth flash the check engine light comes on. Any idea's????
03-11-2013, 06:19 PM
Was it the 10 amp fuse that blew? Fuse is inline with the pink wire on the connector sending power to ICM from the underwood fuse box. Might have a short? Maybe turn the car to ON and check power to ground on the wire since it blew. There should only be one other wire on that plug and its black for ground.
The oil light is flashing? The only way I can think of getting that to flash is when you push the red reset button on the drivers side fuse box when resetting the oil life monitor. Only way to read codes is with a scan tool. I believe the check engine light should be on with key on engine off. If the fuse blew good chance there is a short causing some problems, too much current got through the wire.
04-08-2013, 11:04 AM
I know you said it had a code, but was the security light on? Had the same problem, no spark. Leave the key in the ignition in the ON or RUN position for 10-15mins. It will relearn the resister value and turn the security light off. You'll have spark once again.
No one mentioned it so I thought I should. Seems common for the GA's
04-09-2013, 01:04 PM
This is true, I had that problem a few times. The car would not start, just turned over and when I took the key out the security light would blink. After waiting about 10 mins it would then work.
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