won't start
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RE: won't start
You can get the codes by turning the key to ON, then OFF, then ON, then OFF, the ON (don't start the car).
After a few seconds, the CEL will start flashing at you. Most likely, it will flash once, slight pause, then flash twice, then a longer pause before flashing again. That first one is "12". What you get after that is what we're looking for - all 2-digit codes. The last code you will get is "55". Somewhere on this site I'm sure there is a list of the codes and what they mean.
Alternatively, you can go to your local Autozone and they can pull the codes directly from the OBD-2 port under your lightswitch. That will give you 4-digit codes (like P0135, for example) which are even better.
Only the crank sensor is used for spark control. Both the crank and cam sensor are used for injector control (SEFI) except for the first rotation or so during startup (cam position unknown). We use what is known as a wasted-spark system where two spark plugs get fired at the same time - one on the top of the compression stroke like normal, and the other at the start of the intake stroke/end of exhaust stroke. They are paired 1-4 and 2-3. So the PCM doesn't care where the valvetrain is (which cylinder is actually firing), only which pistons are at/approaching TDC. Hence only the crank signal is needed. So you can pretty much rule out the cam signal as the problem.
A faulty crank signal shouldn't cause only 2 of the plugs to fire. It would end up having no firing at all or intermittent firing with no recognizeable pattern. If the PCM doesn't get a crank signal, the ASD relay switches off, which means no fuel pressure, no injectors firing, and no spark at all. That's why I'd tend to rule out the crank trigger as a problem.
If you've replaced the plugs with good copper ones, replaced the wires with OEM or better (MSD, Crane, Magnecor, Mopar - NOT Nology, ebay...), replaced the coilpack with a known good one (stock, MSD... Autozone should be able to test it for you if unsure), then that pretty much leaves wiring and the PCM. PCM's rarely go bad on their own. That's why I'm betting on wiring... or a second coilpack gone bad...
If Autozone gives you grief about your car being a '95, bet them a soda (or candy bar, or new battery...). Then take them out to the car, show them the sticker under the hood that clearly shows the 1995 model as OBD-2:
Then kindly diect them to the OBD-2 port as described above...
After a few seconds, the CEL will start flashing at you. Most likely, it will flash once, slight pause, then flash twice, then a longer pause before flashing again. That first one is "12". What you get after that is what we're looking for - all 2-digit codes. The last code you will get is "55". Somewhere on this site I'm sure there is a list of the codes and what they mean.
Alternatively, you can go to your local Autozone and they can pull the codes directly from the OBD-2 port under your lightswitch. That will give you 4-digit codes (like P0135, for example) which are even better.
Only the crank sensor is used for spark control. Both the crank and cam sensor are used for injector control (SEFI) except for the first rotation or so during startup (cam position unknown). We use what is known as a wasted-spark system where two spark plugs get fired at the same time - one on the top of the compression stroke like normal, and the other at the start of the intake stroke/end of exhaust stroke. They are paired 1-4 and 2-3. So the PCM doesn't care where the valvetrain is (which cylinder is actually firing), only which pistons are at/approaching TDC. Hence only the crank signal is needed. So you can pretty much rule out the cam signal as the problem.
A faulty crank signal shouldn't cause only 2 of the plugs to fire. It would end up having no firing at all or intermittent firing with no recognizeable pattern. If the PCM doesn't get a crank signal, the ASD relay switches off, which means no fuel pressure, no injectors firing, and no spark at all. That's why I'd tend to rule out the crank trigger as a problem.
If you've replaced the plugs with good copper ones, replaced the wires with OEM or better (MSD, Crane, Magnecor, Mopar - NOT Nology, ebay...), replaced the coilpack with a known good one (stock, MSD... Autozone should be able to test it for you if unsure), then that pretty much leaves wiring and the PCM. PCM's rarely go bad on their own. That's why I'm betting on wiring... or a second coilpack gone bad...
If Autozone gives you grief about your car being a '95, bet them a soda (or candy bar, or new battery...). Then take them out to the car, show them the sticker under the hood that clearly shows the 1995 model as OBD-2:
Then kindly diect them to the OBD-2 port as described above...
Thread Starter
Joined: Jun 2005
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RE: won't start
I know the coil pack is good because i have a second parts car that both the coils work on. i also took the plug and wire from the cylinder that does have spark and put it on the one that didn't and it still does not spark. one question what is the cel??
greg
greg
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RE: won't start
CEL = Check Engine Light. I think the manual refers to it as a Service Engine Soon (SES) light or something like that. Should be on your instrument cluster on the far left hand side, amber in color when lit. If it isn't lighting up at all, the bulb is probably burned out.
Thread Starter
Joined: Jun 2005
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RE: won't start
I pulled the cam sensor off tonight and it looks fine. Could it be bad even thou it's not cracked for worn thru? What else should I try to get the spark back in the 2 middle cylinder?I order a new cam sensor today, it will be in tomorrow should i try changing it anyways?
GREG
GREG
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RE: won't start
There is nothing wrong with your car. Just keep driving, you'll get a big bonus at work eventually and then you can get a new car. First, you might conisder replacing the oxygen senors, everyone else does. Sealing the taillights might help too. Some people have had great success with swapping over to a 5-point seatbelt harness.
Or,
Go back and re-read my post. You are not getting spark to only half the plugs. Either you have another bad coilpack, bad wiring, or a bad PCM. The cam position sensor provides ZERO input to ignition timing. A bad crank signal would not give such neat results. Clear?
Or,
Go back and re-read my post. You are not getting spark to only half the plugs. Either you have another bad coilpack, bad wiring, or a bad PCM. The cam position sensor provides ZERO input to ignition timing. A bad crank signal would not give such neat results. Clear?
Thread Starter
Joined: Jun 2005
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RE: won't start
Ok..............i took the coil pack from another car that ran perfect and swaped it to the car that does not run and still nothing. I also swaped the PCM and still nothing. What should be looking for with the wiring? what should i be getting with a test list to the harness that goes into the coil pack when trying to start it. Why was i told then to change the cam sensor??
GREG
GREG
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RE: won't start
I don't know why you were told to change the cam sensor. Suggestions like that from Chrysler Certified Gold mechanics is why I stopped going to "professional" mechanics.
There are 3 wires going into the coilpack. The middle one (Dk Green/Orange 18g) is a constant power that is supplied by the ASD relay, same wiring that is used for the oxygen sensors and fuel injectors. Chances are, it's fine because a short in that wire would not neatly short out every other crank rotation. The outer two wires go back to the PCM, which the PCM grounds to fire the coil. You can check for continuity between the pins on the PCM end and the connector at the coilpack. On the PCM side, pin #21 is the coilpack driver #1(Dk Blu/Yellow 18g), and pin #1 is the coilpack driver #2 (Black/Grey 18g). On the coilpack end, Pin #1 is the #2 driver, and pin #3 is the #1 driver (same colors). Even then, you might have to wiggle wires around a little to make sure you are getting a good reading. Here's a pic of the '95 PCM pinout if needed:
If you want to inspect and/or replace the wires, there shouldn't be any connectors in between, straight shot to the PCM (ground wires, not the power supply). You'll have to pull off a good deal of sheathing and ubersticky tape to expose all the wiring, plus physical obstructions like the PDC, EGR, etc. Then you have to tape it all back up when you're done. Pins and pin pullers are usually available at Radio Shack. I've had to track down wiring problems before (TPS wire was shorting out), it isn't fun... I feel for ya, and I really am trying to help.
There are 3 wires going into the coilpack. The middle one (Dk Green/Orange 18g) is a constant power that is supplied by the ASD relay, same wiring that is used for the oxygen sensors and fuel injectors. Chances are, it's fine because a short in that wire would not neatly short out every other crank rotation. The outer two wires go back to the PCM, which the PCM grounds to fire the coil. You can check for continuity between the pins on the PCM end and the connector at the coilpack. On the PCM side, pin #21 is the coilpack driver #1(Dk Blu/Yellow 18g), and pin #1 is the coilpack driver #2 (Black/Grey 18g). On the coilpack end, Pin #1 is the #2 driver, and pin #3 is the #1 driver (same colors). Even then, you might have to wiggle wires around a little to make sure you are getting a good reading. Here's a pic of the '95 PCM pinout if needed:
If you want to inspect and/or replace the wires, there shouldn't be any connectors in between, straight shot to the PCM (ground wires, not the power supply). You'll have to pull off a good deal of sheathing and ubersticky tape to expose all the wiring, plus physical obstructions like the PDC, EGR, etc. Then you have to tape it all back up when you're done. Pins and pin pullers are usually available at Radio Shack. I've had to track down wiring problems before (TPS wire was shorting out), it isn't fun... I feel for ya, and I really am trying to help.