I have a 95 2.3L Quad 4 Cavalier and I keep getting a P0342 Cam position sensor circuit low voltage code..... I have replaced the cam position sensor, tested the ignition control module, replaced the spark plugs, replaced the spark plug boots and replaced the coil housing. I'm wondering if my PCM is bad. I hooked a test light up to battery positive and then probed the ground terminal on the Cam sensor connector and the light lit up nice and bright, then I hooked the test light up to battery ground and then probed the positive terminal on the cam sensor connector and the light lit up very dim.... so I located that wire to the PCM and hooked the light to battery positive and the hooked it to the cam sensor positive wire coming right out of the PCM and it did the same thing (lit up very dim) so I know the wire to the sensor is ok. That wire should have battery voltge right? So it should light up bright right??
So.... I have a HUGE favor to ask someone who has a cam sensor perferrably a 2.3 quad 4 but I'm sure the 2.4 is pretty much the same. Can someone with the key ON engine OFF hook up a test light on their car to battery positive, then unplug the cam sensor connector and touch it to the positive wire on the connector (on the 2.3 its the RED wire) and see if the light lights up bright or dim. I just was to know before I buy a new PCM for $125. I would REALLY appreciate it.
Thanks a ton!
Steve
The cam position sensor runs on 5-7 volts from the computer so it will only light a test light dimly. It would only light up bright for close to 12 volts. So your wiring is fine.
I hope you have or can get use of a voltmeter. You need to probe the signal wire for voltage (5-7 Volts) while the engine is running at approx. 1500rpm.
yes, I do have a voltmeter. How do I probe the signal wire? just hook the ground lead on the voltmeter to the ground wire on the connector and then the positive lead to the signal wire on the connector right?
The connector has to be on the sensor, take a paperclip and push it thru the back of the connector for the signal wire. Voltmeter ground wire has to go to Battery negative then voltmeter positive to the paperclip
well I probed the cam sensor signal wire while the engine was running at 1500 and the voltage was around 12 volts???? Think the PCM is bad? I may just replace it because I don't see what else it could be bad, unless there is a wiring issue..... any thoughts
I DONT think your problem is low voltage. remember the cam sensor is supposed to send voltage in increments...on off on off on off in order to judge cam position ....here is what GM si has to say about your engine code.
Circuit Description
The camshaft position sensor (CMP) is used to indicate camshaft position so that the powertrain control module (PCM) can determine which cylinder is misfiring when misfire is present. If the PCM receives an intermittent signal from the CMP, then the CMP Resync Counter will increment. In order to seat a DTC, the PCM must see a minimum number of resync's within a maximum time.
Conditions for Setting the DTC
• Engine is running.
• Cam Sensor Activity is not incrementing.
Action Taken when the DTC Sets
The malfunction indicator lamp (MIL) will illuminate.
Conditions for Clearing the DTC
• The MIL will turn OFF after passing three consecutive diagnostic tests.
• A history DTC will clear after 40 consecutive ignition cycles have occurred without a fault.
• History and current DTCs can be cleared by using a scan tool.
Diagnostic Aids
An Intermittent problem may be caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation.
Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly checked for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wiring connections or physical damage to the wiring harness.
If the PCM sees less than 15 resync's in 256 seconds, the counter is reset to 0. Anytime a poor connection is present, the Cam Sensor Reference Activity Counter will stop incrementing and the Cam Sensor Resync Counter will increment.
Test Description
The numbers below refer to the step numbers on the diagnostic chart.
2.
This step determines if DTC P0342 is the result of a hard failure or an intermittent condition.
4.
Determine if voltage is available to the CPS through the PCM.
6.
If the feed circuit is shorted to ground, the test light will be ON. This step determines if the circuit is open or shorted to ground. If the circuit is OK, then the PCM connections or PCM is faulty.
7.
Voltage will vary between 5 and 7 volts from the CMP sensor. A steady voltage reading near 5 volts or 0 to 1 volt indicates the signal is not being sent to the PCM. Refer to PCM Terminal End View in front of this section for breakout box pin locations.
yeah, I've read all of that on GM SI. I'm a GM tech myself, this one just has me stumped.
i just don't know why its setting a low voltage code......
