Here are some test you can do at home. All that stuff from ALL DATA is meant for shops that have the right equipment. I know most DIY people don't have a $500 104-pin breakout box laying around.
The cam gear is spring-loaded in the fully advanced position, so if the VCT solenoid becomes damaged or malfunctions, the car will still maintain normal operation and performance. However, if the cam gear mechanism malfunctions, or if the timing belt is installed incorrectly, the exhaust cam can end up in the fully retarded position, giving you the same effect as having an EGR valve stuck wide open ... rough idle, stalling, hesitation on tip in, etc.
Three codes relate to this system: Code P1380 VCT Solenoid Malfunction, Code P1381 VCT Over-Advanced and Code P1383 VCT Over-Retarded.
Code P1380 is strictly related to the electrical circuit of the solenoid, PCM and wiring. If the PCM tries to energize the VCT solenoid and doesn't see any current flow or too much current flow, Code P1380 will set. The normal resistance of the VCT solenoid is 3 to 6 ohms. That resistance should not change by any noticeable amount even with changes in temperature. If the resistance is OK at the PCM connector for the VCT solenoid (measuring from the vehicle power circuit, pin 71 or 97, to the control pin for the solenoid - usually pin 44 or 45), you can also perform an amp draw test on the circuit. With the PCM disconnected, turn the key on. Using a digital ammeter, place the negative lead of the meter on battery negative, and place the positive lead to the control pin for the VCT solenoid. The amp draw should be in the 2 to 4 amp range. Only leave the solenoid grounded long enough to get a reading, preferably no more than one or two seconds. The PCM normally duty cycles it, so leaving it fully grounded for more than a couple of seconds can cause damage to a solenoid that is still in working order.
Here's another test you can do to make sure it is mechanically working: With engine running, using a jumper wire, backprobe the ground side of the VCT solenoid. Then rev the engine up to 2,500 to 3,000 rpm and momentarily ground the VCT solenoid; again, only for one to two seconds. You should hear a noticeable difference in the way the engine runs.
This same test can be performed to help diagnose a Code P1381, which indicates that when the PCM commanded the VCT solenoid to operate and retard the cam timing, it did not see any or enough change. This can be caused by a mechanical problem with the cam gear assembly, a bad VCT solenoid, or a problem with contaminated engine oil. Since the VCT solenoid relies heavily on oil flow to create the force to move the cam gear assembly, anything that causes poor oil flow, such as dirty oil, metal chips or flakes in the oil, can affect how well the VCT solenoid functions.
Code P1383 indicates the cam is too far retarded during its â??at-restâ? position. The majority of the time when we see this code, it has set because the timing belt was installed incorrectly. Be sure to check the basics ... make sure the cams and crankshaft are in time.
