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1995 Grand Prix will not start


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jdberry
User

Jul 1, 2009, 2:40 PM

Post #1 of 33 (4377 views)
1995 Grand Prix will not start Sign In

1995 Pontiac Grand Prix
3.1
193000 miles

This car just shut down while going down the road . No warning at all. Would not re-start. I have checked the front plug wire only for any spark and there is none at all. Suspected the Ignition module and had it tested at Auto parts store. They said it was bad, so I replaced it. Same problem-- no fire from plug wires. I checked each coil pack and they tested ok. There is 12V going to the Ignition Module. I checked the CKP by turinng the crank by hand and observing 24 seperate 12 volt pulses per one rev. I replaced the 3X Crankshaft Sensor and check and double checked all wiring to the Ignition module. I even replaced the PCM with a used one. Same problem. This car has the old OBD 1 connector and I do not have access to a reader for it. It also does not have the correct pins available (A and B) to use a jumper and read the flashing "Check Engine" light for code. Out of ideas. Any help would be appreciated.


Sidom
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Jul 1, 2009, 4:19 PM

Post #2 of 33 (4371 views)
Re: 1995 Grand Prix will not start Sign In

That is right in the time frame where it could be OBD I or II, you may need a special adaptor to get a reading.

I'm not sure how you are checking that but you shouldn't be seeing "12v" pulses on the ckp sensor. The 24x is just for easier starting & refining. The 3x is the main signal.

You should get a noid light & see if you are getting an injector pulse....

I not sure how you've checked the wiring but I had a few of those where the harness has been saturated with oil & eaten the insulation off the 2 wires in the twisted pair & shorted them resulting in a no start. To verify that you will either have to scope it at the control module & check your pattern or open up the harness....

If by chance you do need to repair that harness, its important the wires are twisted to help block out interference


(This post was edited by Sidom on Jul 1, 2009, 4:19 PM)


Hammer Time
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Jul 1, 2009, 9:05 PM

Post #3 of 33 (4369 views)
Re: 1995 Grand Prix will not start Sign In

This was a transition year for OBD1 to OBD2. Many of the GM products used an OBD2 connector in conjunction with an OBD1 system. This means that is will not work with an OBD2 code reader and it won't give OBD1 flash codes either. On this one year, you are stuck using a professional scan tool to retrieve any codes or data from the system.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jdberry
User

Jul 2, 2009, 10:10 AM

Post #4 of 33 (4363 views)
Re: 1995 Grand Prix will not start Sign In

I may be talking about the wrong sensor when referred to the ckp. But according to my repair manual its the one located behind the harmonic balancer and I should see either 5-12 Volt pulses with the key in run position as I turn the crank by hand, which I did. When I changed the 3X I examined the wiring harness going to the Ignition module. It looked like it was shorted together at connector on the sensor end. I repaired this and still no spark. What is the voltage level that I should see coming from the 3X. I assume with this type it will be a very small AC volt signal?


Hammer Time
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Jul 2, 2009, 10:54 AM

Post #5 of 33 (4360 views)
Re: 1995 Grand Prix will not start Sign In

There is a very simple way to know if the crank sensor is working or not. Just check for injector pulse using a noid light. If you have that, then the crank sensor is working.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jdberry
User

Jul 2, 2009, 11:48 AM

Post #6 of 33 (4355 views)
Re: 1995 Grand Prix will not start Sign In

Don't have noid light. Will have to find one. Could you tell me what I would be looking for. Just light flashing? Never used one before. I disconnected the wiring harness from both ends of the 3X (at sensor and ign module) and checked continuity and no shorts. I pulgged it back in at the sensor and checked at un-plugged connector and measured ~1K ohm. I checked the orginal sensor and it measured ~ 1k ohm. Either both bad or both good. Do not have the noid light yet so this is the best I could do.


Hammer Time
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Jul 2, 2009, 11:50 AM

Post #7 of 33 (4352 views)
Re: 1995 Grand Prix will not start Sign In

If you get a flashing light when cranking, all is good. If not, check for power on one side of the injector with the key on. If you have that and no flash, then you likely do have a crank sensor problem.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jdberry
User

Jul 4, 2009, 8:40 AM

Post #8 of 33 (4331 views)
Re: 1995 Grand Prix will not start Sign In

Crank sensor checks good
I do have 12 volts at Ign module
All wiring to Ign module checks OK (no grounds and continuity)
Replaced cam position sensor and even battery. Worth a shot?
Out of options


Hammer Time
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Jul 4, 2009, 8:43 AM

Post #9 of 33 (4327 views)
Re: 1995 Grand Prix will not start Sign In

Do you have injector pulse?
Do you have fuel pressure when cranking?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jdberry
User

Jul 4, 2009, 8:47 AM

Post #10 of 33 (4323 views)
Re: 1995 Grand Prix will not start Sign In

I hear the fuel pump when I turn the key to ON
I dont have a noid light
I checked the crank sensor per the Haynes repair manual and tested OK


Hammer Time
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Jul 4, 2009, 8:50 AM

Post #11 of 33 (4320 views)
Re: 1995 Grand Prix will not start Sign In

The noid light costs less than $10 and it is necessary.
If your determined to do this your way, then all I can say is good luck with that.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jdberry
User

Jul 4, 2009, 8:54 AM

Post #12 of 33 (4316 views)
Re: 1995 Grand Prix will not start Sign In

Ok
Are you talking about checking this pulse where it goes into ign module from crank sensor?


Hammer Time
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Jul 4, 2009, 8:58 AM

Post #13 of 33 (4312 views)
Re: 1995 Grand Prix will not start Sign In

I'm talking about pluging a noid light into the end of the injector plug and cranking the engine.





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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jdberry
User

Jul 4, 2009, 9:01 AM

Post #14 of 33 (4306 views)
Re: 1995 Grand Prix will not start Sign In

I figured out what you were talking about.
I will get noid light and check injectors
Original problem was no spark from any of the plug wires
It there something related


Hammer Time
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Jul 4, 2009, 9:40 AM

Post #15 of 33 (4299 views)
Re: 1995 Grand Prix will not start Sign In

Yes, of course. It tells me if the computer is seeing the reference signal from the crank sensor and responding to it.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Jul 4, 2009, 9:42 AM)


jdberry
User

Jul 4, 2009, 10:01 AM

Post #16 of 33 (4293 views)
Re: 1995 Grand Prix will not start Sign In

It will be next day for noid light. If the computer is not seeing this reference signal does that mean bad crank sensor? I have replaced it. The 3X plugs directly into the Ignition module and I have checked this wiring and the wiring from the Ignition module to the PCM.


Sidom
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Jul 4, 2009, 10:53 AM

Post #17 of 33 (4288 views)
Re: 1995 Grand Prix will not start Sign In

You have check all the fuses with a test light I was/am assuming.......Frown


jdberry
User

Jul 4, 2009, 11:34 AM

Post #18 of 33 (4282 views)
Re: 1995 Grand Prix will not start Sign In

I have checked all fuses with voltmeter.


Sidom
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Jul 4, 2009, 12:41 PM

Post #19 of 33 (4278 views)
Re: 1995 Grand Prix will not start Sign In


In Reply To
I have checked all fuses with voltmeter.



Even better!

Follow Hammer's advise......Hopefully he's have some good tests you can run with the equipment you have......... Personally I'm already to the point where I would need a scanner & lab scope to continue on.......


Tom Greenleaf
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Jul 4, 2009, 2:12 PM

Post #20 of 33 (4274 views)
Re: 1995 Grand Prix will not start Sign In

While your at it get a vacuum gauge. At near 200K this timing chain may have jumped. Even cranking vacuum would show that. Just 2 cents in the now long thread,

T



jdberry
User

Jul 5, 2009, 1:23 AM

Post #21 of 33 (4269 views)
Re: 1995 Grand Prix will not start Sign In

Thanks
Would I still have spark at the plug even with timing off?


Tom Greenleaf
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Jul 5, 2009, 2:33 AM

Post #22 of 33 (4264 views)
Re: 1995 Grand Prix will not start Sign In

Off a couple teeth shouldn't prohibit spark but would reduce compression and valve timing off so much it won't run.

If starter cranks engine nicely you will see decent vacuum and starter motor speeds. 18hg would be normal for a running engine and less for just cranking. If lower than say 15Hg - Before you go nuts, also do a wet compression test if fuel and spark are present it should be fine. Vacuum is just simpler but both mean about the same things.

It's not running so #s would be less as it's not warm. Wet meaning a small squirt of oil in a plug hole should cover it being cold - valve timing way off would show up.

Note: 3.1s are interference engines and if valve timing goes completely nuts it will damage the engine,

T



Hammer Time
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Jul 5, 2009, 3:28 AM

Post #23 of 33 (4257 views)
Re: 1995 Grand Prix will not start Sign In

Your starting to get way off the track now. We're chasing a "no spark" problem here.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 5, 2009, 3:56 AM

Post #24 of 33 (4250 views)
Re: 1995 Grand Prix will not start Sign In

Oooops! Thread is so long I lost track! What caught my eye was the miles in top post. Sorry,

Tom



jdberry
User

Jul 5, 2009, 11:27 AM

Post #25 of 33 (4237 views)
Re: 1995 Grand Prix will not start Sign In

Have noid light set now. The injectors are hard to get to . Will have to remove plenum to remove plugs from injector. Is it ok to crank engine with plenum removed? There is a connector where all six injector plugs are fed from that is easy to get to, but will have to rely on wiring diagram and color codes to be correct.






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