2008 2.4l Aura Le5, Rapid click No Start
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Joined: Aug 2024
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Have you checked the lead from the positive battery terminal to the alternator as well as the lead from the positive battery terminal to the starter? The description of the starting points above isn't necessarily quite right because the positive battery cable usually branches so that is what I mean.
The positive cable from the alternator to the battery almost always has an inline fuse. You may have to unwrap it to see it but I would think it's there. It's possible that this fuse has intermittent com activity and may be upset by vibrations under the hood.
The way you describe the dashboard idiot lights lighting up, one by one, and not coming on all at once like a Christmas tree to me reeks of each module losing the current it needs to operate. Each one is slightly different before operation ceases, so the lights come on one by one after it's been running for 5 minutes if the battery happens to not be charging.
Off the top of my head I can't think of another reason that the lights would come on sequentially. Also, the load test passing on the alternator-- what is the pass criteria? I would ask the folks wherever you had it tested what does past mean? Does past mean above 12.6? Above 13-3? Everything is relative and I think in your case that actually matters.
The only other thing I can think of for sequential idiot lights for the dash is that the BCM is controlling a lot of the non-engine related functions, and that the BCM is starting to flake due to low operating current or it is defective.
But it's effective BCM will not turn on the service engine soon light
It's probably time to have the codes red, as we are down to educated guesses.
I also wonder whether or not the problem is somehow heat related such that when the vehicle runs for 5 minutes, something heats up and expands, causing a discontinuity in the wiring somewhere. Or the BCM or ECM goes open circuit somewhere once it is warm. You can possibly test that with a hair dryer. No styling mousse.
You seem like the kind of guy that would own a real heat gun. Don't use that, it is way too hot and will melt shayt
The positive cable from the alternator to the battery almost always has an inline fuse. You may have to unwrap it to see it but I would think it's there. It's possible that this fuse has intermittent com activity and may be upset by vibrations under the hood.
The way you describe the dashboard idiot lights lighting up, one by one, and not coming on all at once like a Christmas tree to me reeks of each module losing the current it needs to operate. Each one is slightly different before operation ceases, so the lights come on one by one after it's been running for 5 minutes if the battery happens to not be charging.
Off the top of my head I can't think of another reason that the lights would come on sequentially. Also, the load test passing on the alternator-- what is the pass criteria? I would ask the folks wherever you had it tested what does past mean? Does past mean above 12.6? Above 13-3? Everything is relative and I think in your case that actually matters.
The only other thing I can think of for sequential idiot lights for the dash is that the BCM is controlling a lot of the non-engine related functions, and that the BCM is starting to flake due to low operating current or it is defective.
But it's effective BCM will not turn on the service engine soon light
It's probably time to have the codes red, as we are down to educated guesses.
I also wonder whether or not the problem is somehow heat related such that when the vehicle runs for 5 minutes, something heats up and expands, causing a discontinuity in the wiring somewhere. Or the BCM or ECM goes open circuit somewhere once it is warm. You can possibly test that with a hair dryer. No styling mousse.
You seem like the kind of guy that would own a real heat gun. Don't use that, it is way too hot and will melt shayt
Thanks for the help DERF you're a legend.
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From: Slightly off center
My test leads, touched together, are 0.1 Ohms.
If your meter is that sensitive to read ohms to the hundredths, then your test leads touched together, unless they are superconducting at room temp, have to read greater than zero or the zero is off when you subtract what they do read from .07, it's going to be too small to matter.
Also, there are many people that contributed to this thread and to finding what appears to be the solution. I wouldn't have brainstormed what I did without everything else that came before it. So you have all of us to thank for the outcome.
If your meter is that sensitive to read ohms to the hundredths, then your test leads touched together, unless they are superconducting at room temp, have to read greater than zero or the zero is off when you subtract what they do read from .07, it's going to be too small to matter.
Also, there are many people that contributed to this thread and to finding what appears to be the solution. I wouldn't have brainstormed what I did without everything else that came before it. So you have all of us to thank for the outcome.
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Joined: Jan 2024
Posts: 623
From: Davison, MI
Operation CHARM: Car repair manuals for everyone.
Home >> Saturn >> 1997 >> SC1 L4-1.9L SOHC VIN 8 >> Repair and Diagnosis >> Powertrain Management >> Ignition System >> Description and Operation >> Electronic Ignition System Circuits and Components >> System Circuits
Power Input
The power input (B+) is tied to the ignition switch (12 volts nominal) and is fed through the ignition switch and EIS fuse.
Electronic Ignition Module
The electronic ignition (EI) module's primary function is to charge up the coil pack upon control of the PCM and to utilize compression sense ignition (CSI) to determine when #4 cylinder has fired on compression. The El module has incorporated circuitry to determine cylinder 4 compression by the use of capacitive pickup plates located under the 1/4 coil. Since each tower on a coil is of opposite voltage polarity and the waste spark event will generally fire before the compression event, the module can determine the polarity sequence. When the module sees a polarity sequence of positive to negative (negative being the high voltage spike), the module will then supply a ground to the number 4 signal wire, signaling to the PCM cylinder 4 has fired on compression. The use of compression sense ignition synchronizes the SFI fuel timing.
Electronic Ignition (EI) Interface
The PCM supplies two signals to the electronic ignition module. One signal is an ignition timing waveform. The falling edge of the timing waveform indicates the beginning of the spark event. The timing waveform is a 0 to 5 volt variable duty-cycle, and frequency, based on the engine waveform and is generated by the PCM to indicate spark advance.
Powertrain Control Module
The powertrain control module (PCM) controls spark dwell, spark advance and the tachometer reference signal to the I/P cluster. All spark advance and retard conditions are controlled only by the PCM at all times.
Secondary Towers
The secondary signal is a high voltage (up to 40,000 volts) timed signal, routed by way of the secondary wires to the spark plugs.
System Inputs
The EI module does not receive a signal from the crankshaft position sensor. Instead the CPK sensor signal is being received and processed by the PCM. The El module does, however, contain circuitry to determine camshaft position without using a camshaft sensor, by use of compression sense ignition (CSI). The CSI circuitry makes use of the characteristics of a waste spark ignition system, while monitoring a sequence of spark plug gap breakdown events. Capacitive pickup plates located under the 1/4 coil are used to determine whether #1 or #4 fired on a compression stroke. This capacitive sensing device is similar to inductive pickups used on engine analyzers and oscilloscopes.
Module grounding
The EI module is grounded through Pin E of the 5-pin connector. The laminated coils have an additional, redundant ground which is provided through the bolt heads to the transaxle housing. The plate on the bottom of the module is used primarily for a heat sink and has no effect on module operation.
pro multis · About Operation CHARM
Home >> Saturn >> 1997 >> SC1 L4-1.9L SOHC VIN 8 >> Repair and Diagnosis >> Powertrain Management >> Ignition System >> Description and Operation >> Electronic Ignition System Circuits and Components >> System Circuits
System Circuits
The electronic ignition (El) system contains input/output circuits and controls two, two-tower coils, each coil firing two spark plugs. The following describes the circuits and components circuits of the EI system.Power Input
The power input (B+) is tied to the ignition switch (12 volts nominal) and is fed through the ignition switch and EIS fuse.
Electronic Ignition Module
The electronic ignition (EI) module's primary function is to charge up the coil pack upon control of the PCM and to utilize compression sense ignition (CSI) to determine when #4 cylinder has fired on compression. The El module has incorporated circuitry to determine cylinder 4 compression by the use of capacitive pickup plates located under the 1/4 coil. Since each tower on a coil is of opposite voltage polarity and the waste spark event will generally fire before the compression event, the module can determine the polarity sequence. When the module sees a polarity sequence of positive to negative (negative being the high voltage spike), the module will then supply a ground to the number 4 signal wire, signaling to the PCM cylinder 4 has fired on compression. The use of compression sense ignition synchronizes the SFI fuel timing.
Electronic Ignition (EI) Interface
The PCM supplies two signals to the electronic ignition module. One signal is an ignition timing waveform. The falling edge of the timing waveform indicates the beginning of the spark event. The timing waveform is a 0 to 5 volt variable duty-cycle, and frequency, based on the engine waveform and is generated by the PCM to indicate spark advance.
Powertrain Control Module
The powertrain control module (PCM) controls spark dwell, spark advance and the tachometer reference signal to the I/P cluster. All spark advance and retard conditions are controlled only by the PCM at all times.
Secondary Towers
The secondary signal is a high voltage (up to 40,000 volts) timed signal, routed by way of the secondary wires to the spark plugs.
System Inputs
The EI module does not receive a signal from the crankshaft position sensor. Instead the CPK sensor signal is being received and processed by the PCM. The El module does, however, contain circuitry to determine camshaft position without using a camshaft sensor, by use of compression sense ignition (CSI). The CSI circuitry makes use of the characteristics of a waste spark ignition system, while monitoring a sequence of spark plug gap breakdown events. Capacitive pickup plates located under the 1/4 coil are used to determine whether #1 or #4 fired on a compression stroke. This capacitive sensing device is similar to inductive pickups used on engine analyzers and oscilloscopes.
Module grounding
The EI module is grounded through Pin E of the 5-pin connector. The laminated coils have an additional, redundant ground which is provided through the bolt heads to the transaxle housing. The plate on the bottom of the module is used primarily for a heat sink and has no effect on module operation.
pro multis · About Operation CHARM
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