becm and ecm help please

BIGDOBBO said:

if the ecu is sending a voltage shouldn't i be able to see that

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Quite possibly - not sure what the voltage is...or even if it relies on an induced voltage generated as the 'Pegs' pass through the Magnetic field produced by the CPS....the ECU then measures the input voltage difference....

A 'scope is the best way as this will measure both a change to a reference voltage or the induced voltage produced by the sensor....

Beyond that I have no clue...I am not an Electronics Wizard, I leave that to Datatek and his co-horts!

As Saint V8 said, the crank position sensor is a hall effect device. It has 3 connections, +ve, Gnd and the signal line. Positive will either be a permanent 5 volts or 12 volts, not sure which. The signal line will either be at close to +ve voltage or close to Gnd depending on the position of the pins on the flywheel relative to the sensor, it should switch between the 2 levels as the pins pass it. It can probably be tested with a DVM, most hall effect transducers can be, remove it from the bell housing leaving the mount in place, with it connected and your DVM on DC volts connected across Gnd and the signal line, move a nice chunky spanner across the surface slowly, the reading should change.

so should i be able to see 5 or 12v from the ecm to the cps? :confused2:

BIGDOBBO said:

so should i be able to see 5 or 12v from the ecm to the cps? :confused2:

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Across 2 of the pins you should read 5 or 12 volts, the 3rd pin will be the return signal. The voltage comes from the ECM, as does the Gnd.

Just looked at the drawings, how many wires do you have at the sensor? My drawing shows 2 wires not 3, in which case one will be Gnd the other will have a voltage that varies.

1997 had 2 wires and 199 on had 3.....

2

so if i have no voltage and a new cps were would you look next ecm?

BIGDOBBO said:

so if i have no voltage and a new cps were would you look next ecm?

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I need to check, the 2 wire one may not be a hall effect device, it may be a sensor that generates a voltage as the pins pass.

RAVE is full of mistakes but it say's the sensor is a Hall effect device on all the versions I can see. So one wire should be Gnd the other should fluctuate as the pins pass the sensor but it must have a voltage on it for the sensor to work.

BIGDOBBO said:

so if i have no voltage and a new cps were would you look next ecm?

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Don't think there is a voltage until the position pin moves past the sensor and induces one. The sensor is a permanent magnet with a coil around it voltage is induced as metal pin passes it. Have you got the stand off of around 0.060" correct it is vital? Whilst there are two wires to the sensor only one is the signal the other is the shield.

do you mean the air gap?

wammers said:

Don't think there is a voltage until the position pin moves past the sensor and induces one. The sensor is a permanent magnet with a coil around it voltage is induced as metal pin passes it. Have you got the stand off of around 0.060" correct it is vital? Whilst there are two wires to the sensor only one is the signal the other is the shield.

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That's one possibility, but RAVE states it's a HALL effect device which is a semiconductor that needs a voltage supply to work.

Datatek said:

I need to check, the 2 wire one may not be a hall effect device, it may be a sensor that generates a voltage as the pins pass.

RAVE is full of mistakes but it say's the sensor is a Hall effect device on all the versions I can see. So one wire should be Gnd the other should fluctuate as the pins pass the sensor but it must have a voltage on it for the sensor to work.

Click to expand...

wammers said:

Don't think there is a voltage until the position pin moves past the sensor and induces one. The sensor is a permanent magnet with a coil around it voltage is induced as metal pin passes it. Have you got the stand off of around 0.060" correct it is vital? Whilst there are two wires to the sensor only one is the signal the other is the shield.

Click to expand...

Saint.V8 said:

Quite possibly - not sure what the voltage is...or even if it relies on an induced voltage generated as the 'Pegs' pass through the Magnetic field produced by the CPS....the ECU then measures the input voltage difference....

A 'scope is the best way as this will measure both a change to a reference voltage or the induced voltage produced by the sensor....

Beyond that I have no clue...I am not an Electronics Wizard, I leave that to Datatek and his co-horts!

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'Tis what I says...

Saint.V8 said:

'Tis what I says...

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Except RAVE clearly states it's a HALL effect device RAVE is often wrong though.
At the end of the day the only way to check without diagnostics is a scope and crank the engine

There is an easy way to check if the sensor is inductive, an ohm meter will give reading across the 2 pins either way round, if it's a HALL effect it should only read with the meter connected one way round if at all.

dose the cps have a live feed or not ?

BIGDOBBO said:

dose the cps have a live feed or not ?

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As you can read from the above - maybe. maybe not....

I know that doesn't help but RAVE isn't clear on how the CPS works....

Datatek gives a check above:

If you can meter a resistance with the probes either way round then it is inductive and doesn't have a 'feed' to it and it relies on it inducing its own voltage which it feeds back to the ECM....

or

If it will only read a resistance in one direction it is a Hall Device and will rely on a 'feed' of either +5ve or +12ve from the ECU.....

BIGDOBBO said:

dose the cps have a live feed or not ?

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Look at the diagrams in RAVE and decide for yourself.

wammers said:

Look at the diagrams in RAVE and decide for yourself.

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Can't tell from the diagrams, it just shows a wire appearing from the ECM and the other end going to Gnd.

Datatek said:

Can't tell from the diagrams, it just shows a wire appearing from the ECM and the other end going to Gnd.

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Don't see any ground. Section 6 Diesel Page 10. Pin 13 back to pin 47. ECU. This is a petrol he has fitted a diesel in if he is using the petrol ECU and the BECM is not set to diesel. They have different pulse rates for tacho. Diesel three pulses per rev and petrol four pulses per rev.

wammers said:

Don't see any ground. Section 6 Diesel Page 10. Pin 13 back to pin 47. ECU.

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It's not obvious I agree, but it picks up the shielding on the CPS and other things on Pages 9, 10 & 15 so I would expect it to be grounded at some point. Just guessing though as it's not at all clear.

Datatek said:

It's not obvious I agree, but it picks up the shielding on the CPS and other things on Pages 9, 10 & 15 so I would expect it to be grounded at some point. Just guessing though as it's not at all clear.

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Read the addition to my last post Keith that could be his problem if he is using the petrol ECU and CPS.