Technical Crank, no start, no spark, no DTCs

[Luke77]

Is the KEY(s) being read ok?

Immob light coming ON.
Then once accepted.. going OFF


Charlie

:bang::bang::bang:

We have two sets of keys at home and I was using the spare set to get the car started and THE CAR DIDN'T RECOGNIZE THIS SPARE KEY -> THE KEY/CODE LIGHT STAYED ON -> and I never noticed .

Took the normal key and VROEMMMM, there the engine went....

Thanks Charlie for taking me back to the start, I was looking far to deep in the possibilities.

:worship:

 

[Luke77]

Re: Crank, no start, no spark, no DTCs - Crank sensor?

I mean:

1 You test the old sensor and new sensor and determine you are able to demonstrate at least one of them is able to produce a signal

2. ***Then*** You remove the ECU plugs and trace which tiny connectors on the plugs has the signal that you have demonstrated the crankshaft sensor is able to produce.

You need a system here. A method.

Also BIG THANKS to you Judderbar!

The solution was dead simple in the end (see above), but it gave me the opportunity to learn a lot about this car (I almost turned the engine compartment upside down).

 

[alan01256]

My FIAT Punto 188 1.2 8v (end 2001) does crank, but doesn't start, due to no spark.

Therefore I replaced spark plugs, to no avail, still no spark seen when testing the sprak plugs.

Read-out with OBD2 gives no pending or stored DTCs.

Ignition coils checked and are within specification.

Tried with a different car battery and still crank but no start.

What could be the problem?
Thought it could be the camshaft position sensor (CPS) or the crankshaft position sensor (CKP), but there is no DTC seen for this sensor in the read-out.

What describe I have just come across on a Ford Focus Mk2 1.6 petrol. In order for the coil to produce a spark you need a 12V supply to the coil itself. On the Focus there are 3x wires. 1x 12V power, 1x Earth & a tach wire for the rev counter. Turned out that 2 of the wires had snapped inside the wiring loom, completely out of sight & at least 12" from the coil pack itself. So start by checking there is an earth path to the body & there is in fact 12v supply to the coil.

 

[Mad one]

What describe I have just come across on a Ford Focus Mk2 1.6 petrol. In order for the coil to produce a spark you need a 12V supply to the coil itself. On the Focus there are 3x wires. 1x 12V power, 1x Earth & a tach wire for the rev counter. Turned out that 2 of the wires had snapped inside the wiring loom, completely out of sight & at least 12" from the coil pack itself. So start by checking there is an earth path to the body & there is in fact 12v supply to the coil.

See above post......he’s cured it ....with correct key?

 

[Luke77]

See above post......he’s cured it ....with correct key?

Yep! Running like a sunshine.

And what we learned all of us, is that the voltage measurements on the CRANK plug (wire A-to-ground) 1,46V; (wire B-to-ground) 2,44V and wire C is the ground wire are normal voltages; so no 5V as on the CAM sensor plug .

 

[judderbar]

Yep! Running like a sunshine.

And what we learned all of us, is that the voltage measurements on the CRANK plug (wire A-to-ground) 1,46V; (wire B-to-ground) 2,44V and wire C is the ground wire are normal voltages; so no 5V as on the CAM sensor plug .

Luke can you measure ohms on the old sensor please? These crank sensor questions often come up and unfortunately nobody outside of fiat HQ seems to have any basic information on what should be normal.

 

[varesecrazy]

Always good to have something to check against.

Probably a valid figure for later 1.2 / 1.4 motors so still VERY relevant on FF.

Charlie

 

[Luke77]

Luke can you measure ohms on the old sensor please? These crank sensor questions often come up and unfortunately nobody outside of fiat HQ seems to have any basic information on what should be normal.

I will do this in the next few days.

 

[Luke77]

Luke can you measure ohms on the old sensor please? These crank sensor questions often come up and unfortunately nobody outside of fiat HQ seems to have any basic information on what should be normal.

The resistance over the old original part MAGNETI MARELLI crank sensor (FIAT OEM 46774532) is about 1158 Ohm (Ω).

 

[judderbar]

The resistance over the old original part MAGNETI MARELLI crank sensor (FIAT OEM 46774532) is about 1158 Ohm (Ω).

Thanks. Does the 1158 Ohms vary when you pass a non-magnetic piece of iron or steel in front of the sensor?

Can you get the sensor to generate a voltage?

 

[Luke77]

Thanks. Does the 1158 Ohms vary when you pass a non-magnetic piece of iron or steel in front of the sensor?

Can you get the sensor to generate a voltage?

The resistance varies between about -50Ω and +50Ω when moving in front of piece of thick steel.

The crank sensor does not generate its own voltage.

 

[judderbar]

The resistance varies between about -50Ω and +50Ω when moving in front of piece of thick steel.

The crank sensor does not generate its own voltage.

Thanks. That sensor is so different to my two wire mk2b one. My one easily produces a voltage sufficient to flash a LED. Your one seems to have two coils? I wonder if g8rpi can clarify?

 

[g8rpi]

That's a new one on me. There are two coil sensors but they are used when yiu need to sense direction, not the case here. The -50 ohms when moving past metal indicates a coil of some kind. You don't get negative ohms (there are cases with RF), it indicates the meter was reading 50mV not ohms because of how the DMM works.


Robert G8RPI.

 

[Luke77]

That's a new one on me. There are two coil sensors but they are used when yiu need to sense direction, not the case here. The -50 ohms when moving past metal indicates a coil of some kind. You don't get negative ohms (there are cases with RF), it indicates the meter was reading 50mV not ohms because of how the DMM works.


Robert G8RPI.

What I meant with -50Ω and +50Ω is, that the resistance was varying between approx. 1100Ω and 1200Ω when moving along metal -> when not moving the sensor the resistance was 1158Ω (therefore -50Ω and +50Ω variation when moving).

 

[g8rpi]

OK,
That is interesting. I still don't what sort of sensor it is. It might be a unamplified/conditioned Hall Effect sensor but very hard to tell.

Robert G8RPI.

 

[judderbar]

OK,
That is interesting. I still don't what sort of sensor it is. It might be a unamplified/conditioned Hall Effect sensor but very hard to tell.

Robert G8RPI.

The manufacturers are saying this 3 pin sensor is an inductive sensor.

 

[judderbar]

Luke, Could I buy the old sensor from you so I can test it and maybe tear it down to see what is inside it? I am curious to know what is going on and be able to document the results.

 

[Luke77]

Luke, Could I buy the old sensor from you so I can test it and maybe tear it down to see what is inside it? I am curious to know what is going on and be able to document the results.

Of course, just send me a PM.

 

[judderbar]

I just finally realised the three wire sensor is not a two coil sensor when it has L 615 and L1 34.5. This sensor has a cable 615mm long. L is length.

After 2003 there is a two wire sensor without the cable attached. L is blank and L1 remains 34.5

 

[judderbar]

Back in 2019, I bought this 2001 1.2 8V sensor from luke77. There are 3 wires but one is just a shielding wire. The only wires going to the sensor are the wires which have the resistance of 1238 ohms. This sensor however seems much less able to produce a voltage than my 1.2 16V 2 wire sensor. I think the problem is the sensor has lost some of its magnetism so a ferrous object passing thru the magnetic field creates less of a disturbance to create electricity. When I change the oil I will compare the magnetism with the one on my car