No Spark, no start, new distributor

The better suspect is a failed crankshaft position sensor. Do you have the convertible or hardtop model? The convertible is the domestic model and it has a camshaft position sensor on the driver's end of one of the cylinder heads. The convertible is a Mitsubishi product that has the camshaft position sensor inside the distributor.

Have you read and recorded the diagnostic fault codes? Do you know how to do that yourself? Have you checked for spark? When do you hear the fuel pump run? It should run for one second when you turn on the ignition switch.

Chrysler does not use history fault codes. Well, they do, but we cannot get to them. Only they have the equipment to read them when a computer is returned for warranty purposes.

The fuel pump should not run for a minute. That would pose a serious fire hazard. Also, fuel pumps do not run until pressure is detected. The purpose of the system is to stop the pump if a fuel line is ruptured in a crash. This is where the camshaft position sensor and the crankshaft position sensor come in. The fuel pump will run for one second when the ignition switch is turned on to insure fuel pressure is up for starting, then it turns off. The engine computer turns the fuel pump relay and/or the automatic shutdown, (ASD) relay on again when the engine is rotating, cranking or running, and it knows that by the signal pulses from those two sensors.

If the fuel line is ruptured in a crash, there cannot be any fuel pressure in that line. No fuel will spray from the injectors, so the engine will stall. Once stalled, there will not be any signal pulses from the cam or crank sensors. In response, the computer turns the ASD and fuel pump relays off.

It is not uncommon to have no fault codes related to these sensors. They often do not set just from cranking the engine. They set when a stalled engine is coasting to a stop. I have a Chrysler DRB3 scanner for all of my vehicles. That lists each sensor with a "no" or "present" to indicate whether their signals are showing up during cranking. I cannot remember if your scanner shows that or not.

I never approve of throwing random parts at a problem, but given your situation, the crankshaft position sensor is the best suspect. Be aware that this one needs to have a very specific air gap. If you just stuff in a used sensor from a salvage yard, it is likely to be hit by the ring on the flex plate and will be damaged. New sensors from Chrysler have a thick paper spacer stuck on the end to set the gap. Push the sensor in as far as it will go, then tighten the bolts. The spacer will slide off as soon as you crank the engine. By that time, it is done doing its thing. You can buy these spacers from the Chrysler dealer's parts department. I cut them into four pieces to save money for my customers.

Some aftermarket sensors have a thin plastic rib molded onto the end to set the air gap. If you remove, then reinstall that style, you are supposed to cut off the remaining part of that rib, then use a paper spacer.

Be aware too that Chrysler made reading the diagnostic fault codes yourself much easier than any other manufacturer. Cycle the ignition switch from "off" to "run" three times within five seconds, leave it in "run", then watch the code numbers appear in the odometer display.

The 2.5L is not listed as an interference engine, but Chrysler does have a safety system built into many of their engine computers where it looks at the relationship of the signal pulses from the cam and crank sensors. If it sees the timing belt has jumped one tooth, it will turn on the check engine light and set a fault code for "cam and crank sync". If it jumps two teeth, the computer will shut the engine down by turning off the ASD relay.

The anti-theft system will be engaged when you charge a drained battery or reconnect the battery. To turn it off, cycle the door lock with the key. If that only works from one front door but not the other one, check for broken or frayed wires between the door hinges. Key in the ignition switch will not reset the system.

For my last comment of value, once you have spark and fuel, the idle speed is going to be too low, possibly to the point the engine will not start unless you hold the accelerator pedal down 1/4". All other data will be relearned except for "minimum throttle". The engine computer must relearn that to know when it must be in control of idle speed. To meet the conditions for the relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the pedals.

I brought up the "cam / crank sync" fault code because the timing belt was replaced. There's plenty of opportunities to make a mistake that leaves the belt loose enough to jump a tooth or two, especially when the engine snaps backward when it's turned of. The idle speed is going to be too low because you had the battery cable off to repair that. Driving the car to work may have not met the conditions for the minimum throttle relearn to take place. The Engine Computer needs to see the very high vacuum of coasting for seven seconds, then it takes the reading from the throttle position sensor and puts that in memory. From then on, it knows it must be in control of idle speed any time it sees that same TPS voltage. Lack of that relearn taking place is a real common cause of a crank / no-start condition. Pressing the accelerator pedal just a fuzz is all it takes to overcome that.

The next thing is to determine if the automatic shutdown relay is turning on during cranking. Look for the wire that is the same color at every injector. Back-probe one of those with a test light. That works better than a digital voltmeter because meters don't respond fast enough. You should see the test light turn on for one second when you turn on the ignition switch. What is important is whether it turns on again during cranking. It should turn on within one or two seconds when the engine is rotating. If it does not, there's a problem with the crankshaft position sensor or with the camshaft position sensor in the distributor.

If the ASD relay does turn on during cranking but you have no spark, the best suspect is the ignition module in the new distributor. If the relay turned on for the first second, but not during cranking, the best approach is to connect a scanner so you can see which signal is listed as missing. That will tell you which sensor and its wires to check. It is common for those sensors to not set a fault code, or it can take an uncommonly long time to do that.

Any new part is a good suspect, even after 7,000 miles. Parts can fail prematurely. Lock bolts can be tightened insufficiently and work loose.

I don't know which wire at the distributor gets 12 volts from the ASD relay. I just searched to verify the injectors do because those are the easiest thing to find. You don't have to check at multiple places for that 12 volts. We just need to know if the relay is turning on during cranking.

It sounds like the wire you found at the distributor does indeed come from the ASD relay, but that is not from the camshaft position sensor. That 12 volts feeds the injectors, alternator field, oxygen sensor heaters, and the ignition coil. If your ignition coil is inside the distributor, that's why that 12 volts is there, and it should pulse on for just one second when the ignition switch is turned on, then again during cranking.

Chrysler and Mitsubishi do things close to the same way, so I'm deferring to my Chrysler experience. There's no 12 volts at the crankshaft position sensor. They are fed with 5.0 volts which is a common power supply to some of the other sensors, and they share a ground return wire that goes through the Engine Computer, THEN to ground. If the 5.0-volt feed wire or the ground wire had a problem, you'd have all kinds of diagnostic fault codes related to those multiple sensors. Since you don't have a pile of fault codes, that leaves the sensors and their individual signal wires.

You can't measure the signals coming off the cam or crank sensors with a digital voltmeter. The sensors put out a square-wave signal that switches from close to 0.00 volts to close to 5.0 volts. On the DC volts scale, the meter takes a reading, analyzes it, then displays it while it takes the next reading. One time it will see 5.0 volts, the next three times it might see 0.00 volts. The reading will bounce around and will be meaningless. Some people try to use the AC volts scale, but the meters are only accurate when reading a 60 Hz sine wave. They don't read square waves, and the frequency will vary all over the place and will also be meaningless. Some high-class meters read frequency and they can read that with square waves, but that won't tell you if the voltage of the signal is as strong as it's supposed to be. The meter could show you have a signal, but if it isn't correct and the Engine Computer doesn't accept it, you'll have a crank / no-start.

The other problem is very few position sensors generate a steady signal. The most common tone ring on Chrysler engines have three sets of three notches for V-6 engines. You get three square-wave pulses, a long gap, three more pulses, another long gap, then the last three pulses, for each crankshaft revolution. Those pulses from the crankshaft position sensor only tell the computer when a piston is coming up on top dead center on the compression / exhaust stroke. The camshaft position sensor is what tells the computer which piston is coming up on TDC.

Some engines have three notches, three notches, then four notches on the tone ring. The computer knows by the four signal pulses when a specific cylinder is coming up on TDC. Those still have a camshaft position sensor, but they can run in backup mode if the cam sensor fails.

Did you read the diagnostic fault codes yet? You can't determine anything related to a jumped timing belt with any meter. The computer learns the relationship between the signal pulses from both sensors. It sets the "cam / crank sync" code when that relationship changes too much, but since your engine is not an interference engine, I don't know if this applies to your car. I only mentioned it previously in case you found that code was set.

You found the 12 volt ASD wire at the distributor, but you didn't say if the 12 volts came back steady during cranking. Let me know what you find there or at the injectors.

I don't understand why you keep referring to voltages coming from the cam and crank sensors. Those are signal voltages we can't measure. We have to let the Engine Computer tell us when there's a problem with them. You found 12 volts at an injector for the first one second after turning on the ignition switch. That single observation proves the ASD relay and its circuitry is working, and the computer has control of it. The second, and more important part of the test is whether that voltage comes back during cranking. It's going to be lower because battery voltage is being drawn down by the starter. The industry-standard is it must stay above 9.6 volts during cranking, but it's more common to find it's around 10.5 to 11.5 volts if the battery is good and fully-charged. The exact voltage is not important. What IS important is that it's there. In fact, since digital meters take too long to respond, I always recommend using a test light for this test. There's no way the exact voltage reading can become a confusing variable. With the test light, the voltage is there during cranking, or it isn't.

Since you have voltage at an injector during cranking, we know the crankshaft position sensor and the camshaft position sensor have to be working. We know that because the correct response from the Engine Computer is it turns the ASD relay on. That relay sends current to the alternator field, the oxygen sensor heaters, the injectors, and the ignition coil. All of this part of the system is responsible for about 95 percent of crank / no-start problems, but we just proved this part is okay. That leaves the other 5 percent of causes. Roughly three percent of the additional crank / no-starts are caused by fuel pump failures, and the last two percent by ignition system failures.

Where some confusion is added to this story is the camshaft position sensor is part of the input signal system that feeds the computer, then the computer feeds the ignition output system and the injector output system. Both the input system, (cam sensor) and the output system, (ignition coil) are inside the distributor. By looking at the 12 volts feeding the ignition coil, we have proven the input half is working, but if you don't have spark, it's the output half that is not working. Since there is also an electronic module built into the distributor that runs the ignition coil, that is the logical place to find the cause of the no-spark, meaning a defective new distributor.

Another way to look at this is when the computer sees the signal pulses from the cam and crank sensors, it turns on three circuits. One is the ASD relay which feeds 12 volts to the ignition coil, injectors, and other places. Basically, it turns on power for the entire engine. The second circuit is the group of wires that pulse the grounds to the individual injectors to open them and allow gas to spray into the engine. The third circuit is the ground for the ignition coil that is pulsed on and off. We need the 12 volt feed to the coil and injectors. We're getting that. Now we need the pulsing ground circuits for the injectors and ignition coil. We don't know if we're getting those, however, those outputs are also monitored by the computer and it will set a diagnostic fault code if a problem is detected. These two circuits cause very little trouble.

Inside the Engine Computer, the driver circuit for the ignition coil is going to cause even less trouble than normal, because instead of driving the ignition coil, which requires a lot of power, it is simply providing the tiny triggering pulse that tells the module inside the distributor when to fire the ignition coil. High-power circuits need high-power transistors, and that always translates into much lower reliability. A power transistor will fail thousands of times more often than a little signal transistor. What was done here is the circuit with the highest chance of failure was moved out of the expensive Engine Computer and put into the less-expensive distributor.

A "noid" light can be connected to one of the injector plugs to see if it is being pulsed by the computer during cranking. If it pulses, it proves the ASD relay is turning on and the computer is running that injector, both of which proves the cam and crank sensors are working. At that point, the no-start has to be caused by no spark OR no fuel pressure, but not both. If you hear the hum of the fuel pump for the first second when you turn on the ignition switch, we know that's working, and the cause has to be no spark. I've never tried this with a regular test light but it should be able to give you some indication as to whether the injectors are being pulsed. You found the wire that is the same color at every injector. That's the one that gets 12 volts from the ASD relay. Move the test light to the other wire, then see what happens during cranking. (This has to be done by back-probing the wire through the connector while that connector is plugged into the injector). I suspect you should see a bright light for one second, then it should be dimmer during cranking. Because the filament glows for a while, I don't think you will see it pulsing, but either dim or pulsing indicates the computer is running the injectors.

You had asked originally about adjusting ignition timing with the distributor. You don't have to worry about that. It's the pulses from the crankshaft position sensor that are very precise and are used for spark timing. Those pulses are very far advanced, in the order of 30 - 40 degrees. Based on engine speed, load, coolant temperature, rate of throttle change, and many other factors, the computer calculates the amount of delay it wants after a crank sensor pulse is received, then it triggers the ignition coil. That's how it achieves the desired amount of spark advance. The camshaft position sensor's signal only tells the computer when a certain cylinder is coming up on top dead center. Even if that were to be wrong, you still have the rotor in the distributor to send the spark voltage to the right spark plug. Even if the wires were mixed up, at worst, as long as the computer is triggering the ignition coil, you'd have spark, but at the wrong spark plugs at the wrong time.

You can test the operation of the ignition coil with Chrysler's DRB2 and DRB3 scanners, and I'm pretty sure you can do that with your MT2500 too. Under "actuator test mode", (ATM), you can select individual injectors or the ignition coil and command the Engine Computer to fire them. It will pulse the selected circuit about once per second. You'll have to listen next to the distributor for the clicking, indicating the ignition coil is firing. You can also remove the distributor cap, then lay a small jumper wire near the coil terminal, THEN continue the coil test while watching for spark. It's a good idea to stop the test while you're removing the cap because the spark voltage may insist on finding a path to ground before you get the jumper wire in place. Depending where that spark jumps to ground, it may leave a carbon track behind. Carbon conducts electrical current, and if that path is easier to follow, spark current will follow that short rather than go down the spark plug wires.

As long as I'm piling on a lot of information, I should mention too how the spark plug wires can be mixed up. This applies to the older Mitsubishi 3.0L too that was used on Caravans and some cars. You must go by the cylinder numbers molded on the top of the cap right next to each plug wire. The terminal the spark is coming out of does not correspond to where the tip of the rotor is under the cap. If you simply start with plug wire number one, then go around the cap in the firing order, four spark plug wires will be in the wrong places. Your symptom will be quite different than the crank / no-start you have now. You would have popping and backfiring which would verify you have spark, but at the wrong time.

Darn the bad luck. I'm leaning toward a defective new distributor, but I wish I was there with my scanner to see it for myself. I have an extra plug-in card that lets my DRB3 work on cars all the way back to '83 models. It has a drop-down menu for crank / "No start" diagnosis, but it has been a real long time since I used that. As I recall, it just takes the pertinent dozen or so items from the list of about 50 things it monitors, and puts them on one screen. You still have to interpret the readings yourself to figure out which is wrong.

Having the scanner helps make the diagnosis easier, but it frustrates me that cars have become so unnecessarily-complicated. Please let us know what the final solution is so I can put that in my memory banks.

Sorry that I didn't explain it better. The Engine Computer turns the ASD relay on two times. The first time is the one second when you turn on the ignition switch. That is to insure fuel pressure is up for running in case it bled down over days or weeks. That one second activation has nothing to do with the cam and crank sensor signals. It will occur regardless if the sensors are good or bad.

The second activation is any time the crankshaft is rotating. That can be while cranking an engine that won't start or run, OR when the engine is running. During cranking and during running is when the cam and crank sensor develop signal pulses. Both sensors are a coil of wire wrapped around a magnet. Whether it's this type of sensor on the engine, a wheel speed sensor, a generator or alternator, you always need three things to generate a voltage. That is a wire, (a coil of wire is more efficient), a magnet, and most importantly, movement between the two. That's why alternators have to be spun by the belt.

In the case of the cam and crank sensors, the movement between the coil of wire and the magnetic field comes from disturbing that magnetic field. That is done in your cam sensor by a piece of metal passing near the tip of the magnet. For your crankshaft position sensor, that is done by passing a hole in a metal plate past the tip of the magnet. Regardless how it's done, it's the movement that is needed for the sensors to generate a voltage pulse, and that means you have to be cranking the engine.

When the signal pulses show up from both sensors, the Engine Computer knows the crankshaft is rotating and it's time to turn the ASD relay back on. That powers up the ignition coil and injectors so the engine will run. This is when we want to know if the 12 volts reappears on that wire at the injector. If it does, the cam and crank sensors have to be generating their signals, and we have a problem in the ignition system OR the fuel system, but not both. When the ASD relay does not turn on again during cranking, it's because the computer didn't turn the ASD relay back on. We won't have spark AND we won't have fuel pump and injector pulses. That's when we have to figure out which sensor signal is missing. Sometimes we get lucky and the computer will set a diagnostic fault code to indicate which signal is missing, but most of the time we have to use a scanner to see that. Each sensor will be shown as "No" when the ignition switch is on, then they should switch to "Present" as soon as you start cranking the engine. When one sensor circuit isn't working, it will not switch to "Preset". It will continue to say "No". That's the circuit we need to diagnose.