Alternate Parasitic Draw Test
BATTERY ELECTRICAL DRAIN / PARASITIC DRAW TESTNOTE: Always check Technical Service Bulletins for any revised procedures or specifications.
The following alternate procedure may be used when testing for parasitic load if Parasitic Draw Test Switch (J 38758) is not available.
Alternate Parasitic Load Diagnosis Procedure:
TOOL REQUIRED:
A/C Delco P/N ST-120l or GM P/N 12303040 Battery Side Terminal Adapters
1. Disconnect negative battery cable.
Battery Side Terminal Adapters:
2. Install the battery side terminal adapter from, AC Delco P/N ST-1201 or GM P/N 12303040 or equivalent, in the negative terminal of the battery.
3. Install the other battery side terminal adapter or a 3/8-inch nut with standard threads (16 UNC) on the negative battery cable to assure a good electrical contact with metal face on cable for testing (add a washer behind nut if nut does not contact firmly). Yellow or black finish nuts are generally non-conductive and should not be used.
4. With all lights, accessories, retained accessory power (RAP), and ignition switch off, connect a high capacity ammeter (at least 10 amps) from the negative battery cable to side terminal adapter. This high capacity ammeter is connected to verify whether or not a high current draw is occurring at a constant rate. It is this type of high current draw which will blow the fuse in lower capacity ammeters.
NOTICE: If a high capacity ammeter is not available, install a section of heavy wire (preferably battery cable section) between existing battery negative cable and side terminal adapter. Allow time for initial draw to occur or check for reduced current with and inductive ammeter (current clamp) and proceed to step 5. With the high capacity ammeter or battery cable section still connected, connect a digital multimeter, set on 2000 mA dc range, in parallel with the high capacity ammeter.
5. Disconnect the high capacity ammeter and take a reading with the digital multimeter.
^ If after 20 minutes current draw is above specifications listed in component parasitic load chart, remove system fuses and mini-breakers one at a time until current draw returns to a value less than or equal to specifications listed. This should be done while monitoring the ammeter so that a disruption of drain will be evident. Refer to Figure above for approximate parasitic loads for various vehicle components. Set ammeter on maximum scale when pulling fuses to avoid damage.
6. When cause of excessive draw has been located and repaired, repeat step 5 to verify the repair. Reconnect negative battery cable to battery terminal.
Tighten
^ Negative battery cable to 15 Nm (11 lb. ft.).