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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> Electrical >> Starter >> Stop And Start System - Diagnostic Codes (2 Of 3) >> Stop And Start System >> DTC P323A-00: Backup Boost Converter "A"; DTC P323A-16: Backup Boost Converter "A" Circuit Voltage Below Threshold; DTC P323B-14: Backup Boost Converter "A" Control Circuit Circuit Short to Ground or Open; DTC P323B-29: Backup Boost Converter "A" Control Circuit Signal Invalid; DTC P323B-38: Backup Boost Converter "A" Control Circuit Signal Cycle Invalid [10/2022 - 11/2023] >> Typical Malfunction Thresholds

Typical Malfunction Thresholds

P323A (CASE 1)

The following condition is met 2 times or more
Back up boost converter control IC power supply voltage Higher than 5.8 V
P323A (CASE 2)

Both of the following conditions are met 20 times or more
Back up boost converter boosted voltage 17 V or higher
Time after Engine restart by engine stop and start ECU Less than 1 second
P323A (CASE 3)

Both of the following conditions are met 13 times or more
Back up boost converter boosted voltage 9 V or less
Time after Engine restart by engine stop and start ECU Less than 1 second
P323A (CASE 4)

Both of the following conditions are met 13 times or more
Back up boost converter feedback control voltage 2.7 V or higher
Time after Engine restart by engine stop and start ECU Less than 1 second
P323A (CASE 5)

Both of the following conditions are met 2 times or more
Back up boost converter boosted voltage 3 V or less
Battery voltage detected by back up boost converter control IC 4.6 V or higher
P323A (CASE 6)

Both of the following conditions are met 98 times or more
Back up boost converter circuit negative power supply voltage Higher than -1.8 V
Back up boost converter control IC power supply voltage 4.2 V or higher
P323A (CASE 7)

The following condition is met 2 times or more
Difference between positive voltage and negative voltages (Back up boost converter output current sensor circuit) Higher than 0.085 V
P323A (CASE 8)

The following condition is met 8 times or more
Back up boost converter output current sensor circuit resistance More than 450000 Ω
P323C

One of the following conditions (a), (b), (c), (d), (e), (f), (g) or (h) is met -
(a) Number of back up boost converter control IC status signal pulse Less than 3 times
(b) Back up boost converter control IC status signal frequency Less than 90.91 Hz
(c) Back up boost converter control IC status signal frequency Higher than 111.11 Hz
(d) Back up boost converter control IC status signal duty cycle Higher than 0%, and less than 7.5%
(e) Back up boost converter control IC status signal duty cycle Higher than 17.5%, and less than 32.5%
(f) Back up boost converter control IC status signal duty cycle Higher than 42.5%, and less than 57.5%
(g) Back up boost converter control IC status signal duty cycle Higher than 67.5%, and less than 82.5%
(h) Back up boost converter control IC status signal duty cycle Higher than 92.5%, and less than 100%
P323D

Back up boost converter control IC power supply voltage Less than 3 V
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