Check V6 camshaft position sensor

Background

OK, the Vectra died and when I checked it there was no pressure at the fuel rail and no pulses received by the ECU from the crankshaft position sensor.

On a Vectra the Diagnostic Trouble Code (DTC) is 0335, which can be displayed for two reasons – engine not running, or ‘incorrect signal received’. My Vectra coughed whilst running, put the ECU light up and then carried on running, ECU light went back out. Tech2 said code 0335 (incorrect signal received) meaning that the engine had been running and something went wrong. Later on that journey it died altogether and refused to start for several minutes. The next day it wouldn’t start at all and no pulses whatsoever were received from the crank sensor.

What and where is the Crank Sensor anyway?

On a V6 (X25XE) the crank sensor is a small cylindrical can with a flange at one end and a single securing bolt hole. The outer end of it as a moulded plastic cable exit.

The sensor itself is fitted to the front of the block, below the oil filter and the cable runs up the front of the engine and across to the triple plug array on the top of the timing belt cover at the front of the engine bay. It’s the front sensor plug of the three.

The sensor is fitted there to produce pulses as an encoded ring attached to the crankshaft rotates underneath it. This ring provides information as to where the engine is pointing at any time and it’s used to provide timing pulses to the ECU.

When the sensor plug is unplugged, there are three pins. Two are ground connections (one is screen, the other is signal ground), the other is the output. Between the pins of the crank sensor cable you should find that one (at one end) and one of the others should give a resistance of approximately 400 Ohms. If you can’t find a combination of two pins with that give this resistance (400-700 Ohms) and the sensor appears to be open circuit or short circuit, then it’s almost certainly faulty.

Next, test it properly…

The sensor itself is a sensitive coil with an internal iron core aligned with the end of the can. Connect a multimeter up to the two pins you identified earlier and set it to a 2V range. Now move a ferrous (Steel, Iron etc) object past the end of the sensor and watch the output indicated on the meter. If it stays at zero, the sensor isn’t working or the piece of metal you’re waving around isn’t ferrous. The indicated Voltage should blip up to about 2V depending on the speed and proximity you move the metal around at.

[B][U]Hints that might point to the crank sensor being faulty:[/U][/B]

• Engine doesn’t start,
• No spark,
• No fuel pressure at the rail after attempting starting,
• Only code 0335 displayed – ‘No Engine Speed pulse’ or ‘Engine speed pulse – Incorrect signal’

If you have access to Tech2, you should see the value alternate irregularly between ‘Active’ and ‘Inactive’ as the engine cranks over.

Hope it helps someone! I’ll update this at some point with pictures and pin numbers.

Ian.