pulsar1230

I have an ongoing problem with my mk2 tt 3.2v6, car has been sitting with an engine fault for about one and half yrs it had a stuck valve . Got it repaired drove it home 30mls, came out next day water all over drive. Radiator was shot so fitted new radiator , let it tick over for 30mins got it up to temperature added more coolent etc and all fine , so I did a scan with V C D S and it showed up two lamda sensors which I replaced and incorrect corrolation between cam sensor G40 and crank sensor G28 so fitted 2 new cam sensors, cleared the codes engine now showing 01 no faults,tried to start car cranking but not starting, fitted new battery, spark plugs , fuel filter, G28 crank sensor, checked all wiring with meter back to engine control module, and its all fine, at the two cam sensors I am getting 5 volts but at the crank sensor I am only getting 2.5 volts . I have watched a lot of videos today on u tube about how cam and crank shaft sensors work and they were described as a 5 volt pulldown sensor producing a square wave basically the 5volts is sent from the ecm down to the sensor and as the crank or cam turns in front of it it pulls the voltage down from 5 to zero telling the ecm when the piston is TDC , allowing it to deliver the fuel and spark at the correct time, but the guy in the videos was saying there are other sensors unrelated which also get 5 volts from the ecm from a common point and if one of these was faulty eg. the coolant temperature sensor it would degrade or destroy the 5 volts going to the crank sensor and thus stop the engine from starting . Having seen these videos I am starting to think its something to do with the fact that I changed the radiator and coolant and somehow this has effected the coolant temperature sensor and unfortunately the car is now with a specialist trying to find the fault so I cant test it as anyone ever heard of this happening before I dont have access to a wiring diagram but if anyone does could they check what other sensors have a common feed with the crankshaft sensor. Any help much appreciated.

IHK 11

Hi i could be wrong and im no mechanic but on some cars the crank sensor or the speed sensor is on the bell housing and picks up a pulse from the magnet on the flywheel. If this magnet is damaged or has come loose then you might not get a spark or a signal. Its a longshot but possible. Good luck!

carchris

does your rev counter move ?if it does its not the crank sensor