jwe123

2002 Mercury Sable 3.0 OHV engine. My Check Enginer Light was on recently and got code P0340 Camshaft Position Sensor circuit malfunction. The car does have a rough idle and engine stalls frequently.

I then measured the votage of the two cables on the sensor connector. The red one (positive power) has only 0.3v while it should be above 10v according to the Haynes Repair Manual. The other one (sensor signal) has a pulsing voltage from 0.2-0.6, while the manual says should be around 5v pulsing voltage.

I also measured the red Power cables of the IAC valve and the Fuel Injectors, all are around 12v. According to the electrial chart on the manual these power cables including the CPS' one are all connected to the same pins on the PCM (Pin 19, 21), so I think the votage has no problem at the PCM side and must be something wrong for the cable between the PCM and CPS. (I measured two points before and after the CPS connector, both 0.3v, so I guess the connector has no problem.)

What should I do now? How can I get this fixed? I'm thinking to make a cable connecting from the IAC + terminal to the CPS + terminal directly. Is that feasible?

Any suggestions are welcome! Thanks.

RickMN

You should be testing power and power ground with the plug disconnected from the sensor. Connect DVOM to power and negative battery terminal with key on. Should be above 10.5 volts. Then set DVOM to ohms and the resistance between the power ground and the negative battery terminal. It should be less than 5 ohms. If more, you have an open in the power ground.

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jwe123

Thank you for your reply. Where is the power ground? I do see the eletrical chart in the repair manual shows there's a Black/white cable connect to the ground, but the CPS connector only has two cables connected to it physically: 12v Power and 5v pulsing signal. How can I find the power ground? Thanks!