DTC Advanced Diagnostics: P16BB
DTC P16BB:Alternator B Terminal Circuit Low Voltage

General Description

Driven by the engine, the alternator generates electricity according to the commands from the powertrain control module (PCM). The local interconnect network (LIN) line is connected to the alternator and transmits/receives information to/from the PCM. The PCM sets a target generating voltage in the range of 12.5 V to 14.5 V and commands the alternator via the LIN line. The alternator output signal (duty signal) is sent to the PCM, and is varied according to the 12 volt battery’s state of charge, the electrical load, and the engine speed. If the FI MAIN RLY OUT terminal voltage and the alternator output are out of a specified value for a set time while the PCM commands a target generating voltage to 14.5 V at a specified engine speed, the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Continuous
Sequence
None
Duration
60 seconds or more
DTC Type
One drive cycle, MIL off

Enable Conditions
Condition
Minimum
Maximum
Engine speed
[ENGINE SPEED]
500 rpm
3,000 rpm
Alternator control mode
14.5 V mode
[ ]: HDS Parameter

Malfunction Threshold
The FI MAIN RLY OUT terminal voltage is 12.0 V or less, and the alternator power generation amount is within 1.0 % to 50.0 % for at least 60 seconds.

Possible Cause
NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
Alternator side B terminal disconnection
Under-hood fuse/relay box side B terminal disconnection
Alternator internal failure
PCM internal circuit failure

Confirmation Procedure
Operating Condition
1.
Start the engine.
2.
Maintain an engine speed [ENGINE SPEED] of 500 rpm to 3,000 rpm.
3.
Turn on the headlights (high beam) and rear window defogger.
With the HDS
None.

Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected, a Pending DTC, a Confirmed DTC, and the freeze data are stored in the PCM memory. The MIL does not come on.

Conditions for clearing the DTC
The Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the 12 volt battery.