Land Rover Repair: crank sensor signal question/2002 disco not starting, crank sensor, square wave signal

Question
John

thanks for offering any advice,  I have  a 2002 Discover series II and we put a new 4.0 crate long block.  we reused all parts from the original engine as it had lost its sleeve and overheated/overpressured the engine.  I am now trying to get it to start and it wont, it cranks fine  no spark, its got 12.6 at coils with 12.5 while cranking, we wonder if its the crank sensor, as have replaced it new again, and it shows the following  1.6 DCV from crank sensor and the ECM to it.  Crank sensor with engine off shows 10hz.  
How can we test if the crank sensor works or if its the ECM.  Alarm system seems to work fine, and only check engine light is on before it turns over.  somethings odd, all harnesses and batteries have been rechecked.

thanks

Bob Bowie in Maine

Answer
I am not sure if you'll be able to solve this at home.  When we swap motors we usually have to use our Land Rover test system to resynchronize the security to allow the car to crank.

If your truck does not crank over you're going to need a shop with Autologic or T4 to proceed.

If it does crank you need to figure out what's wrong on the motor.  Usually people make mistakes swapping wires on crank sensors, and sometimes people plug things together wrong on the injection and top engine harness.


It is a lot more efficient to diagnose this sort of thing with an Autologic because you can see all the sensor readings.

One more thing . . . to test the crank sensor go to the crank sensor pin on the ECU and connect a digital lab scope set to .5v div / .1 sec div and crank the car.  You should see a square wave signal.  The other sensor should be a similar signal for TDC.  You don't test with a meter.