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Engine will not start (run)

Tiny
FREEMBA
  • MECHANIC
  • 1995 PONTIAC GRAND PRIX
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 120,000 MILES
I was driving my 1995 Grand Prix GTP (3.4L V-6)when it just shut off. It would spin over but would not start. It doesn't get a spark, the injectors are pulsing or at least I can smell gas if I spin it over with a spark plug or two removed. I followed a diagnostic flow chart from the dealer concerning a no-start in this car, with this engine. It fingered the Ignition Control module as the problem. Replaced the module and all 3 coils; still no spark. Since then I've replaced both crankshaft sensors and even tried a different PCM. Still the engine will not start. According to a scan tool (OTC) it shows no rpm reading when I'm spinning the engine over. Checked the wires (twisted) from the crank sensor in the side of the block, the readings on them pulsate from.3v to 2v (AC). The module gets 12v when the switch is on. I disconnected the tach wire from the plug-in at the module (read that a grounded tach could be the problem). Still no spark. What should I check next?
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Monday, October 6th, 2008 AT 3:21 PM

6 Replies

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Have you checked the fuses? Both in car and underhood? There are several Ignition fuses.
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Tuesday, October 7th, 2008 AT 4:13 PM
Tiny
FREEMBA
  • MECHANIC
  • 1,152 POSTS
I've checked the following fuses, ign, ecm (pcm), fuel pump, and any other fuse associated with the ignition system. As a matter of fact I've checked all fuses, inside of the passenger compartment and under the hood. The ignition control module gets 12volts with the key on. The PCM gets 12volts as well. I need to know how many volts should each wire in the five (or 6) wire connector at the Ign. Control module get when the key is on as well as when the engine is being cranked. I've put in a lot of time trying to diagnose this problem.
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Tuesday, October 7th, 2008 AT 7:39 PM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Your Crank sensor readings are off, retest and replace if you dont have these numbers.

A malfunction in the crankshaft position sensor circuit will set a related diagnostic trouble code.

To diagnose position crankshaft sensor, the following procedures can be used:

If a scan tester is available, scan RPM parameter while cranking engine. If RPM is indicated, crankshaft position sensor is operating properly. 2. If scan tester is not available, disconnect crankshaft position sensor harness connector. Set ohmmeter to 2-k/ohm position, and measure resistance across sensor terminals. Resistance should be 800-1200 ohms.

Set voltmeter on the 2-volt AC scale. Crank engine and measure output voltage across sensor terminals. Voltmeter reading should be.8-1.4 volts. If resistance reading is not as specified or sensor does not produce the specified output voltage reading, repair faulty wiring or faulty crankshaft position sensor.
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Wednesday, October 8th, 2008 AT 2:23 PM
Tiny
FREEMBA
  • MECHANIC
  • 1,152 POSTS
In my orignial message I said that I've replaced both crank sensors. The readings are within specs. (I noticed that I wrote my readings at the end of my post; however those were the first readings). Can the PASSkey system cause this? (I thought that it only effected starter and fuel) If I use a new PCM does it have to be programmed or does it "learn?" I'm going to check everything over again this weekend.

P.S. I could not get the link you send me to open.
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Wednesday, October 8th, 2008 AT 6:14 PM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
A new PCM will mean reading the old one, then flashing the new one, if not, security module wont work! Forget that.
Have you done a relearn on the pass-key?
GM PASS LOCK RELEARN- Ignition to "run" position, try to start and let key return to "run" position
Approx ten minutes security light will go off
Turn key "off" and wait 5 seconds
Repeat 2 more times for a total of 3 relearns.
Turn key off, then start it
This normally cuts fuel and spark.
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Thursday, October 9th, 2008 AT 5:03 PM
Tiny
FREEMBA
  • MECHANIC
  • 1,152 POSTS
I've tried the GM PASS LOCK RELEARN procedures that you've outline and still there is no spark. I'm going to recheck voltage to the coil pack, and the cranks sensors (to see if they operate correctly). My Mitchell repair info (fromthe dealer) said that if the crank sensor in the side of the block is functioning properly that the scan tool should read engine rpm while cranking. There is no rpm reading during cranking. I've eliminated the tach wire as a possible problem (a grounded tach wire might cause no rpm reading) by removing it from the 6-wire connector which plugs up to the coil pack. I'll let you know what I find by Friday (10/24/08) Email me if you have any info. Thanks.
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Tuesday, October 21st, 2008 AT 11:36 AM

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