Code 65, Fuel Injector Current Low: Notes

The ECM has 2 injector driver circuits, each of which controls a pair of injectors (1 and 4, or 2 and 3). The ECM monitors current of each injector driver circuit by measuring voltage drop through a fixed resistor. The ECM is able to control voltage drop. The current through each driver is allowed to rise to a peak of 4 amps, enabling injectors to open quickly, and is then reduced to one amp, holding them open. This is called "peak and hold". If current can't reach a 4-amp peak, Code 65 is set. This code is also set if an injector driver circuit is shorted to voltage.

1. The following conditions must be present to set a Code 65:
   • The 4-amp injector current was not reached on each circuit.
   • Battery voltage greater than 9 volts.
   • Injectors pulsed "ON" longer than calibrated pulse width.
   • The above conditions met for 20 seconds.
2. Checks ECM and harness wiring to 3-terminal injector harness connector.
3. This test checks for open injector harness or injector.
   NOTE: Although shorted harness or injector will not set a Code 65, problem should be corrected if discovered.
4. Results of step 2) will determine which branch to follow on Code 65 flow chart (2 of 2).
5. Each harness was confirmed as being okay in steps 2) and 3). This test will check remainder of circuit from injectors to ECM.
6. Identifies cause of high resistance found in step 3). A short or low resistance will not cause Code 65, but should be corrected.
7. This test checks for grounded "peak and hold" jumpers. This condition would allow injectors to pulse, but would not allow "peak and hold" operation as current would not flow through resistor in ECM.