Battery Electrical Drain/Parasitic Load Electrical Drain
Battery Electrical Drain
This vehicle is equipped with a battery rundown protection feature. Check the electrical system for an excessive electrical drain if either of the following conditions occur:
| • | The battery is low or dead after the vehicle sits overnight. |
| • | The battery runs down over a period of two to three days. This is referred to as a "parasitic current draw". |
Perform the PCM Draw Test as follows:
- Ensure that the battery is fully charged
- Remove the key from the ignition.
- Close all of the doors. Turn the headlights and the parking lights OFF.
- Turn the courtesy lights OFF.
- Connect the negative battery cable.
- Remove voltage from the PCM memory.
- Connect the milliammeter between the terminals.
Important: Perform the battery electrical drain check after making any repairs.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
DEFINITION: PCM Draw Test | ||||
1 | Read the milliammeter. | below 10 milliamps | ||
2 | The PCM is OK. Perform the battery electrical drain check again to recheck the current drain. | -- | -- | -- |
3 | Disconnect the PCM and recheck the current draw as directed above. | over 10 milliamps | ||
4 | The problem is not the PCM. Check the orn wires for a short to ground. Check the components connected to the orn wires. Refer to "Power Distribution" in Electrical Diagnosis. | -- | -- | -- |
5 | A measurement of approximately 0 amps indicates a faulty PCM. | Approximately 0 amps | -- | |
6 | Replace the PCM. | -- | -- | -- |
Battery Electrical Drain/Parasitic Load Parasitic Load
Parasitic Load test
| • | J 38758 Current Draw Test Switch |
| • | An ammeter with at least 10 amp measurement capacities |
- Disconnect the battery cable from the negative battery terminal.
Refer to
Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.
in General Information. - Install the male end of the J 38758 to the negative battery terminal.
- Turn the J 38758 to the OPEN position.
- Connect the negative battery cable to the female end of the J 38758 .
- Turn the J 38758 to the closed position.
- Road test the vehicle while activating all the accessories (the radio, the air conditioner, etc.).
- Turn the ignition switch to the LOCKED position and remove the ignition key.
- Set the ammeter to the 10 amp scale and connect it to the terminals on the J 38758 .
- Turn the J 38758 to the open position to allow current to flow through the ammeter.
- Wait at least 60 seconds. Check the current reading. If the current reading is at or below two amps, close the J 38758 to maintain continuity in the electrical system.
- Switch down to the two amp scale. Open the J 38758 and check the current reading again for greater accuracy.
- Proceed as follows:
- When the cause of the excessive current draw has been located and repaired, remove the J 38758 and connect the negative battery cable. Reset the clock, the radio, etc.
Notice: Always close the current drain test tool before removing a fuse in order to maintain continuity in the electrical system and in order to avoid damaging the ammeter due to accidental overloading (i.e., opening door to change fuse, etc).
| 12.1. | Current draw less than 25 milliamps is acceptable. Check the charging system for proper operation. Refer to Starting and Charging Schematics . |
| 12.2. | If the current draw is over 25 milliamps, remove the PCM fuse. |
| • | If the ammeter drops more than 10 milliamps after the fuse is removed. Refer to Battery Electrical Drain/Parasitic Load . |
| • | If the ammeter drops less than 10 milliamps after removing the PCM fuse, remove the circuit/system fuses one at a time until the current draw returns to a value less than 25 milliamps. This process will reveal which circuit/system is causing the draw. |
Important: Repeat the parasitic current drain test after any repair has been completed.
