The TPA monitors battery voltage at the B+ and B- cable terminals. If, at any time after the MM contactor is closed, the battery voltage at those terminals drops below the specified level,
Code 19 is displayed. Depending on how low the voltage drops, the control either reduces the maximum current limit to the traction motor or shuts down the traction system. The code is displayed even if the low voltage briefly dropped below the specified level.

Possible Causes and Checks
1. Check the battery voltage by accessing Analyzer Mode, Test 12, Sub-test 12.
2. Check the battery charge level.
a. Check specific gravity on all cells. All specific gravity readings should be within 0.010 of each other. If below 1.175 charge battery and monitor for return of code.
b. Check cell voltage on each cell. If below 1.9 volts per cell, charge battery and monitor for return of code.
c. Check Lift Interrupt Set Level in the Tuning Mode, Code C9.
3. Check for voltage drop in the cables with the battery under load. Pick up a near capacity load, measure volts while accelerating to full speed or while driving up a ramp or grade.
a. Connect positive meter lead to the battery's positive cable. Connect the negative meter lead to the B+ cable terminal of the TPA. If voltage drop is >0.250V, check for bad connection of the battery connector, power cables to the MM contactor, MM contactor tips, or high resistance in the F2 (500A) fuse.
b. Connect negative meter lead to the battery's negative cable. Connect the positive meter lead to the B- cable terminal of the TPA. If voltage drop is >0.250V, check for bad connection of the battery connector or battery negative from the battery to the LPA B- cable terminal and negative cable from the LPA B- cable terminal to the TPA B- cable terminal.

4. Inspect the battery cables for signs of heat or damage.
5. Check the battery connector for correctly crimped contacts. If cable is frayed or thecrimp has failed, replace the cable or correctly crimp on a new connector.
If code is still displayed and all previous checks do not correct the problem, the TPA may be incorrectly reading the battery voltage. Replace the TPA.