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I'm thinking I'm looking at a Crankshaft Position Sensor area problem(Wiring or sensor itself), but.. Something's eating at me about this, so.. Want to toss it out here before I get too focused and wind up costing myself a bunch of time. Plus, I don't have a good scope to check out signals, so..
As the title says, it's a 98 Lumina with the 3.1 V6.. Crank, no start. No indication of attempting to start. This is a friend's car, he asked me to bring my scan tool by.. Didn't tell me the symptoms or I'd have bailed because the lower-end scan tools won't usually show anything in this situation.. There's several codes in it.. EGR and Oil Pressure sensor, but.. Those wouldn't cause a no start. Yes, I did check that Oil Pressure sensor won't cause it to no start. He's had that code for 5 years or so.
First thing I did turned the key on.. Could hear the Fuel Pump running.. Checked pressure.. Good fuel pressure. Turned it over to confirm a crank/no start and that's what we got. Didn't hear anything untowards like the timing chain actually broke or something. I immediately thought Crank sensor.. And.. That's dangerous, because I'm stuck on that now.. But.. I saw one thing doing some further testing that has me questioning it.
The next thing I did was pull one of the plugs.. They're in horrendous shape, but there's no way all 6 went kaput at the same time. Outside of worn out, nothing looks really bad about them. So, with one of the plugs out where I could see it.. Had him try to crank it.. No spark.
That's.. Pointing me even more towards the Crank. This vehicle doesn't have a tach, but my scan tool will show me live data, so I pulled it up and looked at engine RPM while turning it over.. I *AM* getting RPM readings from the PCM. That's what has me doubting myself. Doesn't the RPM signal generally get sent from the PCM based on the Crank signal? I'm almost trying to talk myself out of this, even though live data during crank is not exactly reliable.
I just really don't overly feel like climbing under this thing.. But, that Crank is going to have to be tested so I've got no way around it.. Just.. Looking for someone to poke holes in my theory so that I don't have to get under there and test the crank.
Could be a wiring issue between the crank sensor & the coil(s?). That is the only way I can think of that you would get a signal from the crank sensor & have no spark. What happened before it wouldn't start? Did it happen all of the sudden or has it been sitting awhile?
This site mentions something about wire chafing on the rear exhaust manifold: GM 60° 3.1L V6 Engine
Either way I guess you would need to get under it.
Could be a wiring issue between the crank sensor & the coil(s?). That is the only way I can think of that you would get a signal from the crank sensor & have no spark. What happened before it wouldn't start? Did it happen all of the sudden or has it been sitting awhile?
This site mentions something about wire chafing on the rear exhaust manifold: GM 60° 3.1L V6 Engine
Either way I guess you would need to get under it.
Yeah.. Not really something I want to do, but.. That chafing wire could be a cause.. My understanding, it just wouldn't start one morning. Which seems odd for a chafed wire.
One thing that I hadn't considered, and i'm not sure exactly how to check on this older vehicle.. That old security system that they used back in the 90's.. The resistance based one on the key.. If it were not reading it as a good key, it would give much the same situation.. Because I'm pretty sure that system also just locked out the ignition system when a bad key was inserted. You can still turn the switch and the starter will engage and all that, however, they computer basically disables the spark, preventing the vehicle from running.
THAT may be something to eliminate before climbing under it. I'll have to read up on that system.. I can't recall if there's a dash light for it, and didn't think to look for it, but.. I know on my '05 Colorado, every once in a blue moon the anti-theft will engage and I have to wait 10 minutes for it to reset. Different systems, but I imagine they work in basically the same way.
Yeah.. Not really something I want to do, but.. That chafing wire could be a cause.. My understanding, it just wouldn't start one morning. Which seems odd for a chafed wire.
One thing that I hadn't considered, and i'm not sure exactly how to check on this older vehicle.. That old security system that they used back in the 90's.. The resistance based one on the key.. If it were not reading it as a good key, it would give much the same situation.. Because I'm pretty sure that system also just locked out the ignition system when a bad key was inserted. You can still turn the switch and the starter will engage and all that, however, they computer basically disables the spark, preventing the vehicle from running.
THAT may be something to eliminate before climbing under it. I'll have to read up on that system.. I can't recall if there's a dash light for it, and didn't think to look for it, but.. I know on my '05 Colorado, every once in a blue moon the anti-theft will engage and I have to wait 10 minutes for it to reset. Different systems, but I imagine they work in basically the same way.
Yeah the Passlock system was a PITA. I have a 98 Chevy pickup and haven't had to deal with that issue yet. I think the security light flashes if that is what it is though. I also thought that it wouldn't crank, but I may be wrong about that.
I would think it either has to be that or an electrical issue between the crank trigger & the coil(s).
I used to get an intermittent check engine light that said it was the crank shaft position sensor on a '99 Lumina. I let it go and it would go on and off and the car ran fine. I had replaced the spark plugs and the cables which gave a check engine light for one of the cylinders. The front three are easy, the back three are a pain. I was basically waiting to have the camshaft sensor changed out when I had a new water pump/ new universal belt job done but the car sadly was wrecked.
One thing I did research was a cause for its losing MPG. There was a sensor that goes bad and I was going to have that done too. And, of course, it had the intake manifold gasket job done when the car was about 11 years old. GM cheaped out on a part that only cost a few dollars and that led to a several hundred dollar repair bill down the line for owners. That and the antifreeze they used.
Beyond those problems the car was really holding up. I hope yours is in good shape. It is definitely a car that is safe and kept me alive and relatively unhurt in what was a very bad accident.
I used to get an intermittent check engine light that said it was the crank shaft position sensor on a '99 Lumina. I let it go and it would go on and off and the car ran fine. I had replaced the spark plugs and the cables which gave a check engine light for one of the cylinders. The front three are easy, the back three are a pain. I was basically waiting to have the camshaft sensor changed out when I had a new water pump/ new universal belt job done but the car sadly was wrecked.
One thing I did research was a cause for its losing MPG. There was a sensor that goes bad and I was going to have that done too. And, of course, it had the intake manifold gasket job done when the car was about 11 years old. GM cheaped out on a part that only cost a few dollars and that led to a several hundred dollar repair bill down the line for owners. That and the antifreeze they used.
Beyond those problems the car was really holding up. I hope yours is in good shape. It is definitely a car that is safe and kept me alive and relatively unhurt in what was a very bad accident.
The car is.. Decent.. Yeah, those back three plugs are a nightmare.. The main problem is the person who drives it.. She's worthless.
I'm actually leaning towards this being a Ignition Module problem.. i haven't had a chance to look at it and verify yet.
Like you said, kind of strange that it would go out all at once though.
Let me clarify.. I'm looking at the Ignition Module perhaps not getting voltage in.. And, I pulled up a wiring diagram on the ones on the '98 models... Doesn't look like it would be overly surprising. If the front part of the logic went out.. No spark whatsoever.
I've still got to read the schematics more to tell if i'm right.. But.. Checking voltages is simple, and I can check crank signal from the ignition module as well.. Which avoids the dreaded climbing under the vehicle.
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