Regal L4-2.0L Turbo (2011)
Oil Level Sensor For ECM: Diagnostic Aids
Testing Ground and Low Reference Circuits
Testing Ground and Low Reference Circuits
Because a test lamp can light with up to 200 ohm in a ground or low reference circuit they are not recommended to be used for this type of test. A low
impedance test lamp can light and indicate the circuit is good when there is as much as 20-30 ohm present, while a high impedance test lamp can light
with up to 200 ohm present in the circuit. This is why the Digital Multi-Meter (DMM) is used when validating a ground or low reference circuit
continuity.
When using the DMM there are many vehicle conditions that can affect the ground and low reference continuity testing. If these conditions are not met, a
ground or low reference circuit test can fail on a good circuit. This may cause longer diagnosis time and incorrect component replacement.
Any current flow through a ground or low reference circuit, while being tested, will skew the DMM continuity reading, or display a reading higher than
when there is no current flowing. Performing a ground or low reference circuit continuity test, in reference to the vehicles battery negative terminal, will
have the highest risk of failing a good ground or low reference circuit test than any other ground reference point. The best ground test points would be a
control module housing (if the control modules housing is metal and grounded), door jamb striker (if attached to metal), under dash metal frame work,
engine block, or body ground studs (other than where the negative battery cable is attached).
A typical DMM ground or low reference circuit continuity reading can be as high as 100 ohm with the ignition ON, and drop to 15-25 ohm after the
ignition is turned OFF. The reading will drop below 10 ohm after 30-40 seconds, then below 5 ohm after 60 seconds. Once the vehicle completely goes
to sleep (generally 3-10 minutes) the reading will drop below 0.3 ohm.
The following list of conditions may need to be met to ensure a valid continuity reading on a ground or low reference circuit:
*
Ignition OFF
*
Key out of the ignition switch (when not equipped with keyless entry and remote start)
*
Retained Accessory Power (RAP) OFF (open and close the driver door after ignition OFF)
*
Battery charger set at a 2 A or less charge rate
*
Scan tool not communicating with any vehicle control module (in some cases it may need to be disconnected from the DLC)
*
All entry doors closed
*
Headlamps OFF (auto headlamps disabled)
*
Any delay lighting OFF
*
HVAC after blow OFF
*
Any accessory that can work when the ignition is OFF
*
Wait up to 60 seconds (after all other listed conditions are met)
Activating the DOOR LOCK function with a key fob can greatly reduce the time to achieve a valid ground or low reference continuity test result.
