Parasitic Load Test
The electrical circuitry of the Allante requires that the BCM and central power supply get an initialization charge whenever the battery power is first provided. This initialization occurs with the ignition key in the OFF position, and depending on how long the battery has been disconnected, the initial draw may last for several seconds, and can range between 0.5 and 9.0 amps. The following procedure must be used when testing for parasitic loads:
- Disconnect negative battery cable.
- Install battery side terminal adapter (AC Delco ST-1201). See Fig 1 .
- Installthe other ST-1201, or a 3/8" nut with standard threads (16 UNC) on the negative battery cable attaching screw to assure a good electrical contact with the metal face on the cable for testing (add a washer behind the nut if the nut does not contact firmly). Yellow or Black finish nuts are generally non-conductive, and should not be used.
- 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 the side terminal adapter. This high capacity ammeter is connected to verify where 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. Current is drawn for some time to initialize the CPS. After the initial draw occurs, the ammeter reading should drop below 1 amp. Allow ample time (approximately 30-60 seconds) for the initial draw to occur, or check for reduced current with an inductive ammeter (current clamp), and proceed to next step.
- With the high capacity ammeter, or battery cable section still connected, connect the digital multi-meter, set on the 2000 DCmA range, in parallel with the high reading ammeter.
- Disconnect the high capacity ammeter, and take the reading with the digital multi-meter. A current draw of 50mA or less (25 mA is normal) indicates that all lights and accessories are off, and that there is no unexplained current draw. Care should be taken to allow for a time delay before reading the meter because of the Electronic Level Control Feature.
- Once it has been determined that a parasitic drain in excess of 50mA exists, a visual inspection of the vehicle should be conducted. Check to see if there are any unwanted lights on, motors running or switches/relays activating. If no cause for the draw is immediately apparent, it may be possible to narrow in on the source by systematically removing fuses and circuit breakers, one by one, from fuse panels. This should be done while monitoring the ammeter, so that a disruption of the drain will be evident. See PARASITIC LOAD SPECIFICATION
table.PARASITIC LOAD SPECIFICATION
Component Typical Parasitic Load (mA) Maximum Parasitic Load (mA) BCM 3.6 12.4 ECM 5.6 10.0 Radio 3.0 6.0 Regulator 1.4 2.0 Electronic Level Control 2.0 3.3 Central Power Supply 1.6 2.7 Illuminated Entry 1.0 1.0 Theft Deterrent 0.4 1.0 Power Door Locks 1.0 1.0 Chime 1.0 1.0 HVAC Power Module 1.0 1.0
NOTE:
If a high capacity ammeter is not available, install a section of heavy wire (preferably battery cable section) between the existing battery negative cable, and the side terminal adapter.