DTC 16

Fig. 15 Fuel Pump & Injector Wiring Circuit:

Code 16 indicates that the alternator output voltage is not within specification with the engine running. The ECM monitors the alternator voltage indirectly by checking the voltage of the fuel pump circuit No. 120.
1. With engine running, check voltage at fuel pump fuse using voltmeter J-29125 or equivalent.
2. If voltage is between 10.5 and 15.5 volts, the ECM or ECM connector is at fault. Repair or replace as necessary.
3. If voltage is less than 10.5 volts or greater than 15.5 volts, alternator is malfunctioning and charging system must be checked.