CONFIDENT CAPTIVA
This article is a true description of a problem presented to the AECS technical support team.
Vehicle Holden Captiva LE9 2.4 litre 2012 year Problem presented to the Technical Support Team
We have a client’s Holden Captiva in for service today. The owner complained of flat performance and an occasional check engine warning light on in the instrument panel. The owner would like it fixed but is constrained by a limited budget. I am sure many of us can relate to this particular part of the problem!
The technician had carried out a scan of the vehicle’s engine system with the Launch Auscan, which presented him with fault code P0010.
The code indicates an issue with the camshaft position solenoid control circuit. Let’s see what is happening in this circuit when it is operating. Only an oscilloscope will be able to capture this fast-changing signal, it is the only certain and quick way to identify the fault in the circuit.
“A scan tool tells us where it might be. A scope tells us what it is.”
The workshop had recently purchased from AECS a two channel ATS 500 XM scope kit, completed scope training and had subscribed to AECS technical support. They wanted some assistance in the hook up and pattern diagnosis produced.
Measure
We asked the technician to go into the scopes measurement software and select one of the pre set duty cycle measuring templates. In this case an earth switched solenoid with the engine ECU controlling the earth and subsequent ON/OFF ratio of the solenoid.
The easiest connection point was to go directly to the solenoid’s signal wire by back probing the connector and battery negative which were both easily accessible.
The following pattern was recorded and sent through for technical support and comment.
In the above signal we could see immediately the issue in the camshaft advance control solenoid control.
The duty cycle is the on/off time of the solenoid which is controlled by the engine ECU to send out the required oil pressure to move the camshaft actuator to its predetermined position.
Short
There is a clear short inside the control solenoid, the curve can only mean one thing, and that is that the current in the shorted windings of the valve is too high for the transistor inside the ECU.
New
A new cam actuator solenoid was ordered and fitted. The following pattern was recorded with the new solenoid. We can clearly see our new solenoid switching from system voltage to 0 volts every activation. No more bite marks on earth side of pattern. Our duty cycle is under control sitting at approximately 40 percent with only minor control fluctuations required from it.