booster battery. However, never try to jump start the HV
battery pack with a 12-volt booster battery, or the booster
battery could explode!
Battery Pack Testing
To check battery pack performance, connect a scan
tool to the diagnostic connector on the vehicle and test
drive the hybrid. Watch the combination meter in the
dash as you accelerate and brake. Also use regenerative
braking to try to recharge the battery pack.
The combination meter and scan tool will indicate
battery pack state of charge (SOC) as a percentage of
total charge. They will also show battery voltage, current
draw, and recharge current.
Hybrids often keep their battery pack SOC at approx-
imately 80%. If the battery pack SOC drops below a
preset level, the battery ECU signals the hybrid ECU to
start the engine and use the motor-generator as a gener-
ator is up to almost a full charge.
Chapter 38 Hybrid Drive System Operation and Repair 713
Figure 38-24. Note some of the problems you may encounter
when repairing a hybrid drive train.
Powertrain
ECU failure
Hybrid ECU
failure
Drained or shorted
HV battery pack
Loose or
damaged
power cables
Power control
module problems
Motor-
generator
problems
Figure 38-25. This chart lists hybrid trouble codes from one automaker. If you get a code PO562, you would go to pages 12–39 in
the service manual to get further instructions for testing and servicing the battery condition monitor. (Toyota)
* 1: These DTCs are indicated by a blinking IMA system indicator when the SCS line is jumped with the HDS.
*
2: To determine the correct troubleshooting procedure for these DTCs, jump the SCS line with the HDS, and read the
flash code.