I just acquired a 2000 Blazer from a guy which was troubleshooting it for a long time, most of which was parts replacement. The truck will crank but it does not produce any spark. The codes which are setting is P0336 and p0336 pd. I know the pd is strange but that is what my scanner is retrieving from the ECM. Since I wanted to start from scratch regardless of what the PO said I switched out the Crank Position sensor from a known good running Blazer. After that I verified that the distributor was installed correctly. The strange thing that I found out is that when the distributor is unplugged and the engine is cranked the codes do not appear. Found that the distributor was installed one gear retarded from where it would line up with the number 1 contact in the distributor. Corrected that and thought that maybe the ecm needed to see that the crank and the distributor were timed correctly to send a signal to the coil. Additional troubleshooting I performed; swapped out coil assembly with a known good assembly, swapped out the ecm with a known good working ecm, checked the crank sensor plug for solid and clean connection, checked the coil for 12 volts when the ignition was in the run position which it was.

Can anyone give me some insight as to what I need to do next.

Thanks, Andy

 

Just so that everyone who reads my question knows, I have read the "will not start" sticky as well as many many crank but no spark threads. I have tried all suggestions in the threads. Suggestions which were in the threads were always the same and I have tried above.

Does anyone know where I can get a wiring schematic of the engine wiring harness as well as what each pin on the ECM is for? My ECM has 4 plugs ( blue, black, white and black). The only wiring diagram which I have found " 1283270249" in the blazerforum.com attachments. Problem is that it does not show which plug the pins are in. Please point me in the right direction to get a better diagram / schematic. This would be a great help with further troubleshooting.

PLEASE HELP!!

 

C1 Blue
Gnd ref Purple pin 28
Signal Yellow pin 31

12 v pwr to CKS Pink from ECM1 in underhood fuse


Part 1 -GM 4.3L, 5.0L, 5.7L Crank Sensor Test.

 

No start may be prevented by the neutral safety switch on the trans. It may be out of adjustment.

 

On my car, that keeps it from cranking.

 

If I remember correctly the ignition does nothing if the neutral safety switch is out of wack. Do you have spark at the coil?

 

No spark at the coil even if I tap a ground wire on the plug connection which sends a pulsing ground from the Ignition control module (unplugged from the Ignition control module of course). I bought a brand new coil but still the same thing.

I seems that no matter what item in the ignition I unplug the ECM does not set any codes but as soon as all components are plugged in the system sets the P0336 "Crankshaft Position Sensor A Circuit Range/Performance".

Additionally I have verified that all sensors have the required voltage applied. I found that the crankshaft position sensor did not have any voltage at the pink wire like there is supposed to be. I cut the pink wire leading to the CPS plug and temporarily ran a wire between the ignition control module pink wire. Cranked the engine again and still no spark.

Just in case there is a short or broken wire between the CPS and the ECM I cut the entire CPS wiring out of a spare wiring harness I have and am going to try that tomorrow.

Can anyone tell me that why there might be no spark when all ignition components have correct applied voltage and all components are known to be good or are brand new to include the CPS and still no spark? Am I missing something here???

Neutral position sensors do not disable the ignition. They disable the starting circuit.

 

Actually the ignition coil is an LC circuit. You need an old fashion 'condensor' from the neg post to grd for that to work right.but did you actually run the test in that link?
Part 1 -GM 4.3L, 5.0L, 5.7L Crank Sensor Test.
If you didnt then you might think power and grd are getting to the CKs but doesnt mean it works. test it at the pcm connector
What would cause the fuse or circuit power to open?

Only thing not addressed yet is distance of sensor {gap} from the sprocket teeth.Yep.. same on every car I ever had...not worth arguing except for the sake of the future reader.

 

Thanks Pettyfrog,
Only thing not addressed yet is distance of sensor {gap} from the sprocket teeth.

How do you set the sensor gap. It seems to be a drop in and go part. Do you just bend the metal plate? btw, how can you tell what the gap is when the sensor is installed since you can't see the gap due to everything being covered by the timing cover?

I have not run the test which you sent a link to yet but will today. I'll post results tonight.

I am starting to feel like this guy.

 

I got it running this morning. I tested the circuit for the crank sensor and everything was fine except for it not pulsing 5 vdc when the crankshaft was turned manually. The troubleshooting sheets all say that the sensor is bad if this is detected. I removed the sensor, with the ignition on and touched the sensor to a piece of steel I had handy and wala, a pulse. Glad I did not just run to the store and buy a crank sensor! For some reason the timing cover did not allow the sensor to get close enough to the trigger wheel on the crankshaft. My fix was to take my air tool which I use to remove old gasket material with 3M pads and removed a little bit of the plastic from the mounting surface for the sensor until I had a gap which provided a pulse. Hooked everything back up and wala it started! The previous owner had replaced the timing chain as well as the timing cover (as the cover states to do) and something which I never do when changing the timing chain.

Thanks either way for the assistance fellas, Andy