P1628 Sensor Reference Voltage 2 Circuit Erratic

P1628 code - PCM recognizes the secondary 5-volt supply circuit voltage is verying much too quickly. Default actions the MIL light illuminate, the ETC light flash, if the vehicle is equipped with the stop/start feature, the system will disabled when this DTC is active.

P1628


Possible causes P1628 code

- 5 volt supply circuit intermittently shorted to ground
- 5 volt supply circuit intermittently shorted to voltage
- 5 volt supply circuit intermittently open
- MAP sensor
- Camshaft position sensor
- Camshaft position sensor 2
- Accelerator pedal position (APP) sensor
- Powertrain Control Module (PCM)

Diagnostic test P1628 code

Step 1. Check for an intermittent connection in the engine wiring harness
Diagnose any active or pending sensor reference high or sensor reference low DTC before proceeding with this test procedure. If this DTC is present without an active or pending sensor reference high or sensor reference low DTC, the most likely cause is an intermittent open or short circuit in the wiring harness between the engine and the PCM.
Turn the ignition off.
Disconnect the MAP sensor harness connector.
Connect a voltmeter to the 5-volt supply circuit at the MAP sensor harness connector.
Make sure that there is a good positive connection between the voltmeter lead and the MAP sensor harness connector terminal since we are looking for an intermittent connection.
Turn the ignition on.
While monitoring the voltage reading on the voltmeter, wiggle test the entire engine wiring harness all the way to the PCM.
Look for any quick changes in the voltmeter reading. The voltmeter should read steady 5 volts +/- .01or .02 volts with the Throttle Body Assembly harness connector unplugged.

Did the voltmeter reading change from 5volts at any time while wiggle testing the wiring?

Yes, repair the 5 volt supply circuit for an intermittent open or short circuit in the wiring harness. Make sure to check all of the in-line connectors for poor connections or spread terminals.
NO, go to step 2.

Step 2. Check for an intermittent connection in the APP wiring harness
Turn the ignition off.
Disconnect the APP sensor harness connector.
Connect a voltmeter to the 5-volt supply circuit at the APP sensor harness connector.
Turn the ignition on.
While monitoring the voltage reading on the voltmeter, wiggle test the wiring harness between the APP sensor and the PCM.

Did the voltmeter reading change from 5.0 volts at any time while wiggle testing the wiring?

Yes, repair the 5-volt supply circuit for an intermittent open or short circuit in the wiring harness. Make sure to check all of the in-line connectors for poor connections or spread terminals.
No, go to step 3.

Step 3. Check the secondary sensors
Turn the ignition off.
Reconnect the MAP sensor harness connector.
Reconnect the APP sensor harness connector.
Disconnect the PCM harness connector.
Connect a voltmeter to the 5-volt supply circuit at the PCM harness connector.
Turn the ignition on.
While monitoring the voltage reading on the voltmeter, lightly tap on each sensor listed in the possible causes table.

Did the volmeter reading change from 5.0 voltsa at any time while tapping on one of the sensors?

Yes, replace the sensor that caused the voltage to change.
No, go to step 4.

Step 4.  Check related PCM and component connections

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