cranks but won't start

Are crank sensors supposed to have power on them?

I would still check the left bank (bottom) crank sensor wiring. Can you do a wiring check between the ECU and the crank sensor? Pins 47 and 48.


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You may not be able to see the wiring colours, but you should be able to figure out which pin (socket?) on the sensor plug (car side) connects to what socket on the ECU connector.

It's common for the plugs on the crank sensors to fall to pieces. The plug may be damaged internally. You may have hit the sensor plug or wiring as you were installing the shields.

 

The crank and cam sensors are different types. The cam sensor is a Hall Effect type and needs voltage.

https://www.underhoodservice.com/tech-feature-understanding-the-differences-challenges-between-crankshaft-position-sensors/

 

When the ECU senses engine rotation during cranking, it activates the ECU relay ("O" or "L" depending on the bank) which provides power to things like the fuel pump relay coil (which in turn powers the fuel pump fuse) and provides (oddly) power back to itself so it can carry out more functions.

Sorry if I'm teaching granny to suck eggs here

 

When you say no power to crank the rev counters, do you mean you get no tacho indications? No (or erratic) tacho indication may be a sign that your left bank (5~8) crank sensor or wiring is inoperative.

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(EDIT: I can't remember if the starter motor cranks the engine fast enough to register on the tacho)

 

I think that by "no power to the crank rev counters", berlinetta f355 means no power to the crank sensors. There is no incoming power to these sensors, they generate "power" (an AC voltage) and send it to the ECU-s.

 

I'm not sure if you have access to a scan tool (SD1) to read RPM as the ecu reads it. When crank sensors fail, they usually send an erratic signal to the ecu which results in the loss of injector drive and spark. I think Ian has you headed in the right direction with the verification of crank and cam signal wiring (including ECM grounds). I would check ALL of the grounds, and power feed circuits too.

 

The crank sensors are PASSIVE. They are not powered ever. They generate a voltage through magnetic induction which the ECU reads. The sensor has a magnet in it wrapped by a coil of wire. The magnetic field around the conductor changes due to the rotation of the toothed wheel on the engine, thus generating the voltage in the coil.

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I believe that you mean Motronic 2.7 (2.1 was not used in 355).

I have a 348, Motronic 2.7, and I believe the sensors on the 355 are the same. There are two Crankshaft Position Sensors (2-pin connectors) next to each other, each related to one bank, under the engine at the connection between the engine and gearbox. No power is supplied to these sensors, they generate electrical signals which are sent to their respective ECU-s.

There is only one Camshaft Position Sensor and it is mounted at the back of the RH head camshaft. This sensor has a 3-pin connector and it gets power supplied to one of its pins at ignition "on". The sensor caters for both banks, i.e. sends its signal to both ECU-s.

 

??? Crank sensor on a 355 are located at the front of the engine, one to the side and one directly under. They are 3 pin connectors" Signal, Signal ground and shield ground.

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20002 and 20005 for cars with one cam sensor. I believe early 355s had 2 cam sensors and 2 crank sensors. Don't know the numbering for them.

 

20007 is a thermocouple ECU.

As JohnK says, 20002 and 20005 are, respectively, the left and right bank crank sensors on the lower front part of the engine. The cam sensors are on the rear upper part of the engine and are 20010 and 20011 (left and right respectively). On F355 2.7 cars, there are two of each. Miro (m.Stojanovic) may be thinking of the F348 2.7.

JohnK's photo shows the location of the two crank sensors. As shown in my mini graphic in post #5, the crank sensor for the left bank is on the underside of the crank. It is NOT on the left hand side of the engine (as seen from the rear of the engine). Your left bank light is illuminated.

If you do a resistance check on the left hand crank sensor wiring (with the crank sensor connected) by using pins 47 and 48 of the left hand ECU connector, it might tell you if the wiring and sensor are ok (see post #2). I just checked the resistance of a spare (new) crank sensor and it was around 900 ohms.

 

My wiring diagrams should be more helpful to you than the WSM versions:

https://www.dropbox.com/t/OThozgriPnSYe7eR

https://www.dropbox.com/t/iIVVKzc4QCTr1pHE

Links expire in 6 days.

 

Only early 2.7 cars had 2 cam sensors. Later ones, like mine, had only one cam sensor mounted on the rear of the cam cover on the right side of the motor.

Around 900 0hms is correct for the crank sensor.

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Strange. I can't imagine you have problems on both sensors. I wonder if there is an error in the original diagrams (on which my diagrams were based). I have found pin numbering errors in the engine diagrams on the 5.2, but that was a sequence of 70 pins shifted one pin to the left and was easy to identify. Oddly, the same mistake was made on the Ferrari 456M wiring diagrams. If you have time, perhaps you could check the pins adjacent to 47 and 48?

 

Thanks, John. When you said early cars (earlier), I thought you just meant the 2.7's. I didn't realise there were variations between 2.7's. I'll add a note to my diagrams relating to this.

Your last photo has confused me even more. Were the crank sensors also moved on some cars or is the image reversed or is it a 348?

Ferrari 348 engine out...

https://www.ferrarichat.com/forum/posts/142755093/

 

@berlinetta f355

I don't know if you're aware, but on one of the diagrams in the WSM, the left and right bank crank sensors are mislabelled. i.e. on page "C9". Elsewhere, the labelling is correct.

 

The picture in post #18 is a 348 motor. Don't know what happened to the text that said that. Some times my laptop does strange things with text. I usually catch it but missed it this time, I guess. Sorry. It was supposed to say that 348s also had the crank sensors up front, but positioned differently than a 355.

 

I sometimes have trouble with FChat depending on which computer device I use. Rob (the moderator) has just told me I "Report"-ed several innocent posts recently. I apologise to the posters (if they were notified).

 

Yes, I screwed-up. Probably because I recently replaced the crank sensor on my Daimler Super V8 which sits at the bellhousing, 2-pin connector.

The 355 2.7 had, in addition to the RH Cam Sensor ("Phase Sensor"), a similar Cam Sensor on the Left Head but up to Engine No. 38321.
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