[ 2012 Mazda Mazda2 ] No spark condition
Hello! I am having a small issue with my 2012 Mazda Mazda2; the spark plugs are not sparking!
A story explaining what occurred:
I was driving and the serpentine belt began whining (high pitch squeeling noise); the acceleration fluctuated and within 30min while traveling between 5mph and 15mph the serpentine belt snapped apart (broke). I was trapped in traffic and had no where to exit nor a safe shoulder to pull over on. I quickly realized what had just occurred when I smelled burned rubber, saw the CEL/MIL light turn on along with the check battery light! I pulled over as soon as I could.
I tried changing the serpentine belt and soon after realized that the serpentine belt tensioner pulley's bearings were seized. I immediately removed the belt and sat for an hour.
For reasons I cannot say: I was forced into driving (pulling over everytime the engine temperature sensor emitted and started blinking and for as long as I could hold out for, safely).
The engine inevitably overheated which caused the cylinder head to warp (by about ~55mm). I have since then managed to replace the cylinder head along with the master cylinder head gasket.
At that point: The spark plugs properly worked. Currently, for reasons unknown: The spark plugs do not produce a spark.
A summary of the issues experienced:
- Spark plugs do not produce a spark
A summary of what was damaged and how:
- Engine overheated
- Cylinder head warped
- Crankshaft position sensor partially melted
- Camshaft sensor partially melted
A summary of parts replaced:
- Cylinder head (mildly warped; compression values are within specs)
- Crankshaft position sensor (new)
- Camshaft position sensor (new)
- Waterpump (new)
- Idler pulley (new)
- Serpentine belt tensioner (used)
- Serpentine belt (new)
- Spark plugs (x4; all new)
- Ignition coils (x4; all new)
A summary of parts tested:
- Fuses (all passed; x1 15amp fuse blade went missing)
- Relays resistance readings (all but one passed; x1 reading at 66ohms; unknown DC volts until later this week)
- Spark plugs (in specs; gapped properly)
- Crankshaft position sensor air gap (within specs)
- Ignition coils (13yr old parts tested within specs; one mysteriously damaged while I was at work); new ones have NOT been tested!
The wiring harness, the PCM/ECU (from within the air box where the two large 40-pin connector boxes conjoin at) or a relay (IG 1, IG 2 or the Ignition switch found under the steering wheel on the lower right) are the only culprits I could conceive of.
The pin outs can be found at the following URL:
The "main relay" reference can be found at the following URL:
The OBD II reader last said that the PCM could not talk to the TCM (which rendered opening the hatchback electronically impossible); someone had bent the white wire while I was away at work (they broke into my car and have repeatedly; other damages have not been found).
Aside from that DTC: I cannot think of any others. I can, upon request reconnect the battery and read the OBD II DTCs (the engine cannot run; the key will go as far as ACC due to the no-spark-condition).
To clarify: The motor turns over from the starter motor; the engine's pistons are timed with the dual overhead cams and harmonic balancer as well (10th tooth using the visual aids and manually inspecting the valves being depressed with the DOHC); to the best of my knowledge: It IS timed correctly! There is no spark being generated.
Is there anything I could be missing...? The main fuses (from just after the battery's positive terminal) are all three in good, functional and working condition. A preliminary test showed continuity from one wire traveling from the main harness' connector box (PCM) all the way to the ignition coil's wire (the only one I tested that still failed to produce a spark).
The battery is filled with a mixture of: Tap water, sulferic acid and magnesium sulfate (a lesser acidic medium than sulferic acid; as someone had broke into my car and dumped it on the ground). The battery both holds a charge and was last reading/tested at: 12.7v+ (90% - 100% charge).
I have access to a MULTIMETER; not an oscilliscope! I am pretty sure the battery is not the culprit, but am open to any suggestion.
Thank you in advance. 
Best Answer
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thecardoc3
Member Posts: 5,811
That's the proper way, and the result should be very close to 0v, definitely less than .5v. You said you had 12v, if that is the case that is a failed ground.Muted said:DMM's negative lead to battery negative terminal; DMM's positive lead to metal bolt on the car's chasis; DMM set to read 20 DCV.
Is this an incorrect procedure...? If so: What is the proper way to test for a ground short and ground fault using a DMM?
If you don't have proper system voltage all bets are off as far as how the vehicle is going to behave.
Ground shorts? "Multifactorial" problems? Diagnostics, when you are trying to prove or disprove multiple causes simultaneously is nearly impossible. The weight of the information will more than likely leave you unable to process it. You need to pick a circuit that you have made a legitimate observation about and then test and prove whether that circuit is operating correctly or not. If it isn't then you adjust your test points until you determine the root cause. Then and only then should you consider another circuit. Diagnostics is NOT making a bunch of measurements with no real idea of what information you can gain from the testing.Muted said:
Yes! Exactly. I was attempting to rule out any multi-factorial problems (EG: Ground shorts, ground faults, faulty ECUs, faulty wiring, etc).
Where are you located? Or better yet use this search to see if there are actually members of the iATN near you. https://iatn.net/repairMuted said:
No. The shops available do not conduct such testing. This is from the horses mouth. Their only response (by company policy) is to suggest to a customer to replace the allegedly defective part (which may or may not solve the issue).
Damage a connector pin, fail to fully reseat a connector, false codes and more. Those are some of the most common things that we find. I often have to work my way through multiple problems when someone has attempted to diagnose a vehicle. In most of the cases many of these problems were clearly caused during the previous failed repair and diagnostic attempts.Muted said:I am unsure how. If I test a faulty CKP and identify that the ECU is failing: I don't see how that could 'add' an additional issue. Speaking of: The MAF is faulty (not correctly registering the called for 0.67v) nor the insignificant resistance between the two pins (A and D, I believe; I'd have to cite ma2auto, again).
There is no acid inside a diode that can leak. In fact while there is one component that can fail and leak it's extremely obvious when that happens. The most likely substance you are noticing is left over solder flux.Muted said:ADDITIONAL INFORMATION:
The PCM is damaged. There is a short being caused by leaked acid from either a diode or another unidentified component.
All of those voltage measurements are just noise. You need to know what you should measure on a given pin under what conditions and either prove whether the circuit is correct or not. You need measurements key on engine off, measurements when attempting to start the engine, if it cranks measurements while the starter is cranking the engine. In many cases a voltmeter isn't sufficient to give you all of the information and you need a digital oscilloscope.Muted said:These are the voltage readings (KOEO); DMM neg. lead on battery neg. terminal post; DMM pos. lead inside of the PCM connector box.
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"Ground short". If a circuit is shorted to ground and it's before the load, the circuit protection will take the power away (aka blown fuse)Muted said:These are reflecting a damaged PCM (which agrees with a visual inspection of the PCM).
As always: Thank you for your help, I appreciate your time and you. I am not convinced the no spark condition is being strictly caused by a damaged PCM (meaning: A faulty ECU, ground short and/or fault or other also exists concurrently).PS: The incorrect voltage readings only suggest a failed PCM (an $1,800 part or $250 repair).
If a circuit is shorted to ground that controls a ground side commanded device, that will simply cause the circuit to be "On all the time" while the short is present.
A ground fault (high resistance or open) will result in an excessive voltage drop across the ground. Gound circuits under load(with current flowing) should be less than .2v drop.
0
Answers
Do you have power to the ignition coils when the key is in the run position and when cranking the engine?
Do you have power to the fuel injectors, and can you use a test light and see if they are being commanded to deliver fuel? You can use a stethoscope, or a screwdriver and try to listen to them too. Let me know if you can hear them clicking.
Make sure you record any codes you find before this next step. Disconnect the camshaft position sensor and attempt to start the engine. If it fires whether it starts or not let me know. If it starts shut it back down right away. If this makes it fire then you most likely do not have the camshaft in time with the crankshaft. If there is a large enough error in the camshaft/crankshaft sync the system might be disabling the spark to try and protect the engine from further damage. Now recheck for codes and see if the camshaft sensor signal code has set whether this fired or not.
This model does not have a separate TCM (transmission control module) from the PCM. That's probably a software issue with your code reader. Make sure you identified the vehicle correctly.
Hello, thecardoc3.
Thank you so much for the very quick, informative response and OK! I will do that tomorrow afternoon when I'm able to.
Thank you. I have previously tested the fuel safety cut-off switch, fuel pump, pressure regulator, fuel injectors and related sub-systems (electrical assumptions) using this exact method before; I will perform the test, again and report the results.
NOTE: The top of the engine smelled of fuel and the exhaust pipe as well (implying both: The fuel system is functional as well as a proper vacuum).
I do not know. I have no assistant and am unable to properly mount the multimeter to where I can read it from within the cabin of the vehicle. Is there an alternative method or will I be forced into finding a solution of some sort (such as longer cables, tape, cloths and so on)?
I have not properly tested the fuel injectors (resistance and voltage) using a multimeter; I do not have a test light, noid light nor an oscilloscope; I only possess a multimeter. (ASSUMPTION) To the best of my knowledge: The fuel system is functional; however: I will test the fuel injectors' circuits to help eliminate them as a potential culprit. Thank you.
Thank you! I did not think to temporarily remove the camshaft position sensor as a test.
I have a quick question: If the CMP is being interpreted as not present (disconnected or damaged): Will the PCM enter a type of 'default' or 'limp' mode and attempt to run or do typical modern (2010+) CAN bus systems prefer to disable other ECUs (such as the spark plugs' controllers / systems)?
Also: I will scan the current DTCs (ACC first; attempt to crank the engine secondly and post the results of both prior to clearing the codes and attempting your suggestions).
Oh! Thank you. I was unaware and was only quoting what the BlueDriver OBD II reader had reported. The sensor I located that has a damaged wire (hopefully repaired with electrical tape) is actually the VSS (vehicle speed sensor) according to ma2auto.
The URL is at the following:
On that notion: Is it possible for the VSS to be a causation for the PCM to disable the spark plugs? I would assume it is unrelated, but I do not know.
Without listing all of your suggestions of which I will attempt: Thank you, so very much! I will try to accompish as many as I can, tomorrow and report the results as soon as I am able to.
The sweltering heat is a major impedence for me to work on my vehicle.
Thank you, again.
EDIT: This URL agrees with a DTC error relating to the "TCM" found under the "BCM" (body control module) DTC tables:
"Communication error to TCM" is the DTC I was referring to (U0101:00).
I cannot seem to find the correct URL, however, this is yet another citation:
This is the final URL I can locate and it provides no additional information of use to me (at least that I can make sense of):
I will continue to search...
This URL features a brief wiring diagram which depicts the TCM as apart of the PCM (internally):
Would this imply a diode or other component within the PCM itself is damaged and requires either a physical repair (replacement of component or total replacement of the PCM)? Sorry and thank you.
Final edit: The battery is holding a charge (12.2v, currently); the battery was last fully charged over a month ago; that does not say whether or not it's discharging properly as expected (no load test has been performed).
I disconnected the CMP and attempted to start the engine; the DTCs to not appear to have changed (2v below 12v now). I will try to get the battery recharged and repeat the procedure and test the wiring harness for the ignition coil / main relay / ignition switch / CMP / CKP / ECT / IAT sensors at a later date.
I tried to organize the data to the best of my abilities below. Thank you very much for the suggestions so far...
The only issue currently present is a no spark condition and nothing else. The fuel system, vacuum system, timing system and so on have been ruled out.
DEFINITIONS:
DCV (direct current voltage): ⎓
Resistance (ohms): Ω
Hertz: ㎐
B+ voltage: Unimpeded battery voltage (ideally: 12.2v+)
ESA: Electronic Spark Advance
CKP: Crankshaft position sensor
CMP: Camshaft position sensor
ECT: Engine coolant temperature sensor
QUICK URL TABLE REFERENCES:
QUICK PCM TERMINAL REFERENCES:
[ TERMINAL ] [ SIGNAL NAME ] [ CONNECTED TO ]
[ 1X ] [ Starter relay ] [ Starter relay ]
[ 1AJ ] [ Main relay ] [ Ignition coil ]
[ 1BE ] [ Main relay ] [ Drive-by-wire control ]
[ 1BF ] [ Main relay ] [ Ignition coil ]
[ 1BG ] [ Main relay ] [ Ignition coil ]
[ 1AQ ] [ Fuel pump control ] [ Fuel pump relay ]
[ 2D ] [ Ignition coil power supply ] [ Ignition coil ]
[ 2AQ ] [ ESA control ] [ Ignition coil #1 ]
[ 2AR ] [ ESA control ] [ Ignition coil #2 ]
[ 2AU ] [ ESA control ] [ Ignition coil #3 ]
[ 2AV ] [ ESA control ] [ Ignition coil #4 ]
MISCELLANEOUS DATA:
CONTROL SYSTEM DIAGRAM ( https://www.ma2auto.com/control_system-1109.html )
PCM VOLTAGE REFERENCES ( https://www.ma2auto.com/pcm-1110.html )
Battery status: Connected
PCM wiring harnesses (x2): Connected
Battery voltage: 11.25 ⎓
Key position: OFF ACC [ ON ] START
PCM DTCs (codes cleared; tried to start engine; read codes; copied below; Voltage: 0.98v from 12.2v after cranking):
[ PERMENANT ]
[ Instrument Panel - Control Module / PATS ]
[ Electronic module - TPMS / PATS ]
[ Power Steering - Control module ]
[ ABS Module ]
REFERENCE URL:
EXPECTED: No data ("replace that ignition coil")
Ignition coil connector boxes 1-4
(+) pin 1 to (-) battery (-): 9.80 ⎓
(+) pin 1 to (-) pin 2: 9.85 ⎓
(+) pin 1 to (-) pin 2: 550 Ω (key out)
(+) pin 2 to (-) pin 1: 606 Ω (key out)
(+) pin 2 to (-) pin 1: -812 Ω (key in)
(+) pin 1 to (-) pin 3: 7.30 ⎓
Ground circuit
(-) pin 2 to (+) battery (+): 11.20 ⎓
Trigger circuit
REFERENCE URL:
EXPECTED: ~12.0 Ω between terminals A & B (pin 2 and pin 1)
Fuel injector connector boxes 1-4
(+) pin 2 to (-) pin 1: 9.25 Ω
(+) pin 2 to (-) pin 1: 7.30 ⎓
REFERENCE URL:
EXPECTED: 1.2mm - 1.3mm air gap, ~20 Ω
Spark plugs (E3.48 Diamond Fire) 1-4:
Cylinder #1: 1.016mm gap, ~4000 Ω
Cylinder #2: 1.016mm gap, ~4000 Ω
Cylinder #3: 1.016mm gap, ~4000 Ω
Cylinder #4: 1.016mm gap, ~4000 Ω
REFERENCE URL:
EXPECTED: 0.5mm - 1.5mm air gap, "rectangular waves are produced"
Crankshaft position sensor (CKP):
Air gap: ???
RESISTANCE ???
VOLTAGE ???
REFERENCE URL:
EXPECTED: "rectangular waves are produced"
Camsaft position sensor (CMP):
PCM terminal references (pins):
{ Main relay system }
PIN: 1AJ [ MAIN RELAY ]
STATES: [ B+, ≤ 1.0 ]: Switch ignition coil to OFF, switch ignition coil to ON
PIN: 1BE [ DRIVE-BY-WIRE CONTROL ]
STATES: [ B+, ≤ 1.0 ]: Normal, malfunction
PIN: 1BF [ MAIN RELAY, "B+" ]
STATES: [ B+, ≤ 1.0 ]: Switch ignition coil to ON, switch ignition coil to OFF
PIN: 1BG [ MAIN RELAY, "B+" ]
STATES: [ B+, ≤ 1.0 ]: Switch ignition coil to ON, switch ignition coil to OFF
{ Fuel pump system }
PIN: 1AQ [ Fuel pump control, "Fuel pump relay" ]
STATES: [ B+, ≤ 1.0 ]: Switch the ignition to ON after a certain amount of time has elapsed, cranking / idle (after warm up; ECT #1 and ECT #2?)
PIN: 1AE [ CAN_H, DLC-2 ]
STATES [ UNKNOWN ]: Indeterminable
{ Starter system }
PIN: 1X [ Starter relay ]
STATES: [ ≤ 1.0 ]: Idle (after warm up)
{ Ignition coil system }
PIN: 2D [ Ignition coil power supply ]
STATES [ B+ ]: Switch the ignition to ON
PIN: 2AQ [ "ESA Control," Ignition coil #1 ]
STATES [ UNKNOWN ]: Ref. cited
PIN: 2AR [ "ESA Control," Ignition coil #2 ]
STATES [ UNKNOWN ]: Ref. cited
PIN: 2AU [ "ESA Control," Ignition coil #3 ]
STATES [ UNKNOWN ]: Ref. cited
PIN: 2AV [ "ESA Control," Ignition coil #4 ]
STATES [ UNKNOWN ]: Ref. cited
FUEL PUMP STATUS:
Take a look at the above codes. This is setting communication codes where the instrument cluster is losing communication with the engine control module. (U0100) The instrument cluster is responsible for getting the theft deterrent information from the key and sending that on to the engine control module to tell it if it is OK to allow the engine to start or not. Without that security information the car is not going to start.
Is the theft warning light on or flashing when you attempt to start the car?
Current list of DTCs are as follows:
Yes, I can hear the fuel pump turn on.
Yes, there is power when the key is in the ON position.
I do not know the state during an engine crank cycle.
Yes, the fuel injectors have power and are being commanded to deliver fuel.
No, I do not have a test light.
The stored DTCs have been shared (review above). They remained unchanged inbetween.
No, the engine did not fire (0.98v battery power; only a relay clacked on and off).
Okay.
No, the PATS light is not enabled.
Thank you, again. I'll reply / post updates as I'm able to.
I asked about hearing the fuel pump at key on for two seconds and then hearing it a second time after cranking the engine. Hearing it the second time tells me that the engine control module is seeing the crankshaft sensor signal. That is important because it is the primary input to get the computer to command the ignition system to fire the spark plugs. How did you confirm that command, by listening to them or what?
By chance have you pulled the spark plugs back out after trying to start the engine and are they wet with fuel? In some ways this definitely looks like a theft deterrent system problem, which can easily be caused by a loss of communication between modules. But, some important details are missing and that might be a tooling issue. At the same time there are other gaps in the information that aren't allowing for a complete picture to be presented. This should have set a camshaft sensor circuit code when the engine was cranked with it disconnected.
In the shop I would be using an oscilloscope to watch for the ignition coil command from the ECM. I would at some point take a fuel sample just to be sure that the fuel isn't contaminated. I would also directly capture the camshaft and crankshaft sensor signals and make sure that they are correct and in sync with each other. You might have no other choice but to get this to a shop and have it diagnosed. You're going to have a difficult time overcoming tooling deficiency.
https://enginecodesinfo.com/mazda-p0126-engine-code/
Thanks for the URL, but I believe the DTCs are more or less a false positive (a direct result of another underlying root cause).
No, I did not disconnect the IAT sensor at any point; it was always connected.
Oh! Okay. To be clear: I hear the fuel pump prime (KOEO); I could not crank the engine due to the battery having a ~10v charge; ONLY the main relay clacks on and off. I will attempt this test this following Saturday (Sept. 6th); the battery is currently at ~12.2v or so (I believe the battery may be sulfated due to age and abuse and should be replaced soon; the magnesium sulfate and tap water works as a sulferic acid and distilled water solution replacement, but it is only ideal if the vehicle is able to run properly).
I used a DMM to verify the ground and power terminals on the connector boxes (x4 fuel injector connector boxes); I smelled fuel vapor above the engine cylinder head AND fuel vapor emitting out of the exhaust pipe (drawn through by the vacuum produced from the engine cranking over); I do NOT have an osilloscope, an assistant or another means to verify.
No, the spark plugs (all four) are not fouled with carbon, fuel, water, oil or any other substance (minus the insignificant amount of blow back due to no detonation).
The PATS system (instrument panel) isn't indicating any such thing; when the battery voltage drops too low: It will illuminate on some start attempts (which is expected) along with other abnormalities (the circuit exists and is complete in that sense).
I am providing as much information as is available to me and I am acquiring it to the best of my abilities (impoverished equates to limitations (financially)).
I agree. The CMP sensor being disconnected and the CAN bus not flagging a DTC is alarming, however: The battery was showing ~10v (0.98v) with the DMM during the conductance of that test. I will perform it, again on the 6th of September (Saturday).
I should note: I found a single ground terminal that is showing 0v during a voltage drop test; the wire with a plastic clip on the lower right passenger side, by the A/C clutch, by the radiator. I am unsure. All other grounds have been verified as showing B+ voltage (battery voltage) as expected; one or two may have been showing +/- 1v less than B+ (no corrosion). I did not document which ones, but I will photograph them, retest them and provide a detailed post.
I agree. The automechanic shops that are available 'do not diagnose electrical issues' such as these; their solution: Require you to purchase replacement items (blindly). Although that does and will work: That's not a route I'd prefer to take.
I will be testing ALL available PCM terminals tomorrow after work and I will share the results (along with the battery voltage captured just prior to testing and the key state (KOEO or key out) per terminal), along with a quick retest of ALL ECU sensors and connector box terminals (DCV / ohm).
Hopefully that will fill in more data and allow for a better resolution of the potential culprits of the no spark condition.
On a side note: I managed to remove the four stripped torx screws holding the PCM in; without an osilloscope, smart tweezers or an ESR meter: I cannot readily test the capacitors or power lanes on the circuit board (also: I am unable to desolder them, energize them or deplete them due to a lack of tools). However: The PCM's capacitors, PCBs and other components VISUALLY look okay; I see two spots where there is an orange liquid that apparently oozed a small snail trail across a power lane (four lanes); I will post photographs with the next post I make here.
I intend on cleaning the PCM off with isopropyl alcohol, cotton swabs and blue shop towel (taking care to not leave behind lint; a quick run with a cigarette lighter should burn off any fuzzies). There is a strange white powder (not necessarily dust) that crept in from outside (not the white powder added to the board for protection; that is all over the plastic housing on the inside and is fine).
Last note: The PCM's wiring harnesses are fine (every terminal I tug tested lightly); everything appears to be making good contact; when inserting and removing the harnesses: I am abiding by the technical manual's technique of lining the connector straight and applying pressure until the overhead latching bar moves (and I usually press on the lever to help it snap together).
I apologize for the strange issue and I do sincerely thank you for taking the time of day to help me with diagnosing the issue.
Thank you.
Here is a (poor) photo of a component with orange liquid oozing about:
I will share better photographs hopefully as early as tomorrow.
Then you say this. If you don't have proper system voltage all bets are off as far as how the vehicle is going to behave. You are mistaken about shops that test correctly, there are a lot of good technicians, you just need to find one near you. The biggest concern about just running around and testing this or that without a solid game plan is you could unintentionally add additional problems to the car and end up making it worse instead of closer to being diagnosed.
DMM's negative lead to battery negative terminal; DMM's positive lead to metal bolt on the car's chasis; DMM set to read 20 DCV.
Is this an incorrect procedure...? If so: What is the proper way to test for a ground short and ground fault using a DMM?
Yes! Exactly. I was attempting to rule out any multi-factorial problems (EG: Ground shorts, ground faults, faulty ECUs, faulty wiring, etc).
No. The shops available do not conduct such testing. This is from the horses mouth. Their only response (by company policy) is to suggest to a customer to replace the allegedly defective part (which may or may not solve the issue).
I am unsure how. If I test a faulty CKP and identify that the ECU is failing: I don't see how that could 'add' an additional issue. Speaking of: The MAF is faulty (not correctly registering the called for 0.67v) nor the insignificant resistance between the two pins (A and D, I believe; I'd have to cite ma2auto, again).
ADDITIONAL INFORMATION:
The PCM is damaged. There is a short being caused by leaked acid from either a diode or another unidentified component.
These are the voltage readings (KOEO); DMM neg. lead on battery neg. terminal post; DMM pos. lead inside of the PCM connector box.
These are reflecting a damaged PCM (which agrees with a visual inspection of the PCM).
As always: Thank you for your help, @thecardoc3! I appreciate your time and you. I am not convinced the no spark condition is being strictly caused by a damaged PCM (meaning: A faulty ECU, ground short and/or fault or other also exists concurrently).
Thank you!
PS: The incorrect voltage readings only suggest a failed PCM (an $1,800 part or $250 repair).