06 Mazda 3 LF 2.0 Cranks but No Start

Good day,

I have mazda 3 lf2.0

Cranks but no start

Injectors are working but no spark

I have these codes
P0335 - rpm does not register on my scanner. furthermore details, scanner indicates "Maximum threshold".
P0328
P0661

I have performed continuity checks, short to power and short to ground on the crankshaft sensor harness. there seems to be no problem.

Switched my multimeter to AC 200V
I cranked the engine and the wire harness of the crankshaft sensor registers 00.1V during cranking , is this normal?

The crankshaft sensor should output .8 v or less on the low rpms, and 4.8 v or more on high rpms

I assume the low rpms is idle but not 100 % sure,

Do you have battery voltage on pin C??

Do you have ground on pin A ??

If so I would suspect a faulty crankshaft sensor.

thank you for the reply

the voltage I gave was in AC, because the crankshaft sensor is vrs type.

I have question. is the wire in crankshaft sensor ground be connected to the shield wire?

I understand its in ac for the signal wire.

do you have battery voltage 12v dc and ground on the other wires. if so, I would replace the sensor

other wires? meaning other wires than the crankshaft sensor wire? if so, yes there is 12 volts on the other positive wires.

is there any way to bypass test this vrs type sensor? I watched some of the videos that this type of sensor is a floating ground which makes it difficult to impossible to bypass test

is this weird? I pulled out the crankshaft sensor and manually use my screwdriver to replicate a cranking scenario and I can hear the fuel pump priming and yet no spark.

ok, update ..

p0335 - fixed this through engine timing, the engine was out of timing.
p0328 - the ks sensor socket was not connected well.
p0661 - Replaced variable intake-air solenoid valve ( checked this through resistance meter, turns out the valve was open circuit ).

then... there is one appeared after fixing all these problems,

p0511

when I start the engine, the car flares up then rattles until it dies. I checked the IAC in the diagnostic, it only gives 0% , does this mean that it is not functioning or is there any other problem I need to see. is this also caused by a faulty coil plugs? I have one coil plug that doesn't spark.

ok update about p0511

from my understanding p0511 checks lights on if the iac + is in abnormal values like in this case when I add load to the iac wire by plugging it in to iac the voltage in iac + drops to 7v which makes this code appear. ( Is this a case of voltage drop? )

IAC is a two wire IAC which lifts up the iron nail to open the bypass air.

notes*
IAC resistance is at 10.4 ohms
continuity harnes from IAC to ECM are good, no short to ground

diagnosis..

1.) my hard guess was the transistors on the ecm probably blew up or is bad so I sent the ecm to the technician to have it checked and it turns out the transistors are good. so next ..
2.) I checked terminals positive and negative posts on the battery, and discovered that the negative terminal wire is corroded badly... Can this cause the engine light? p0511

If you keep your foot on the gas pedal, or open the throttle manually, can you keep the engine running? If you can, you can keep digging into the P0511 and why the engine can't inhale.

If you still can't keep it running, then P0511 may be a red herring. Are there any other dash lights on KOEO or KOEC?

yes the engine can keep running or does not stall when i open the throttle body. the code itself means that there is a problem with the circuit, i wonder if the transistor of the iac is shared to other solenoids.

btw thank you for replying

***nope there are no more codes that comes up, only this p0511 even with KOEO or KOEC

jobzinfinity wrote: yes the engine can keep running or does not stall when i open the throttle body.

Sweet. I mostly wanted to make sure there wasn't an antitheft issue.

***nope there are no more codes that comes up, only this p0511 even with KOEO or KOEC

OK, we can work with that. With the IAC plugged in and unplugged, KOEO, check both wires for voltage with your meter connected to B-.

What are the wire colors at the IAC?

Ok with my test KOEO
unplugged IAC
IAC+ wire gives out 12v
IAC- wire gives out 0v
plugged IAC
IAC+ wire gives out 7v
IAC- wire gives out 2v

I forgot the color wires but i have a pin out diagram of the iac

The 7V on the IAC+ sure doesn't sound right. KOEO, IAC plugged in, can IAC+ light your test light when connected to B-?

no, there is no light on the test light when I connect it on iac + wire while its pluggin in iac. the 7v on iac drops to 0v. test light connected to B-

Sounds like a voltage drop to me.

Where are you located? Because I just tried to look up P0511 in service info, and couldn't find it for the '06 Mazda 3.

sadly Im located in south east asia philippines. Yep, I think its a voltage drop, one culprit that I am thinking is it is probably the corrosion on the negative wire terminal on the battery post.

here is also the service manual for the p0511 code