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JASON
JASON, Auto Service Technician
Category: Car
Satisfied Customers: 288
Experience:  ASE MASTER AND L1 ADVANCED AUTO TECH 17 YEARS EXP, 6 YEARS GM DEALER, 2 YEARS FORD, 2 YEARS TOYOTA,7 YEARS CHRYSLER DODGE JEEP RAM
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No spark, wont start...crank..coils..ive replaced the cam sensor

Customer Question

I have a 2005 Land Rover LR3 that came in with the concern "No spark, won't start.". I checked for spark at cylinder 1 and found that it does spark, but just one time during a crank cycle... like it's trying to find its position.

I've checked all fuses, verified that all coils have adequate power and good grounds. I've replaced the cam sensor which seems to be the only viable input to the ECM to help it determine position and also replaced the ECM. The cam sensor is disconnected, the vehicle does not set a code for it, is that supposed to happen ? The crank sensor is transmitting RPM just fine. I've checked all the wiring between the ECM and the cam sensor, between the ECM and the coils. I see no signs of physical damage and the only water intrusion evident is near the GECM.

I'm not sure how else to proceed or what else to check.... has anyone had a similar problem ? Any ideas on what I could do next ?
Submitted: 5 years ago.
Category: Car
Expert:  JASON replied 5 years ago.

JASON :

does the scan tool show an rpm input when you crank it?

JASON :

if yes, you need to check your power and grounds into the pcm one lead on a pcm ground and the other on a pcm power input wile cranking you need to make sure you have 12 volts.

JASON :

have had several ignition switch problems with a 4 volt loss from swich, normally i use a voltage drop test by putting one lead on the positve terminal of battery anr the other lead at each of the positive inputs to the ecm one at a time, this is voltage drop, which is a measurement of the amount of voltage you are loosing through the circuit this reading should not be more than .3 of a volt, any more than that and the circuit has high resistance, most commonly the ignition switch.

JASON :

you need to leave the ecm plugged in and back probe each circuit the same way, voltage drop check each circuit, remember you are checking each circuit with one lead at the beginning of the circuit at the battery and the other lead at the other end at the ecm