Battery - Discharging Due to Component Current Drain
84ford12Article No. 84-15-9
BATTERY - MAINTENANCE-FREE - DISCHARGED DUE TO COMPONENT CURRENT DRAIN - DIAGNOSTIC PROCEDURE
FORD ALL WITH MAINTENANCE-FREE BATTERY
LINCOLN-MERCURY ALL WITH MAINTENANCE-FREE BATTERY
LIGHT TRUCKS ALL WITH MAINTENANCE-FREE BATTERY
Discharged maintenance-free batteries could be caused by the following:
1. Glove box, hood, trunk, or courtesy lights staying on because of misaligned or faulty switches.
2. Cooling fan relays, antenna motors and other energized components remain on.
3. Pinched or grounded wire harness.
To determine whether a constant current drain condition exists, it is necessary to perform the following test:
Constant Current Drain Test (Non-Message Center Equipped Vehicles)
Use a regular 12-volt test light for this test:
1. Be sure all vehicle electrical circuits are turned OFF. To check for minimum battery charge and/or condition of bulb, connect test lamp across battery terminals. Lamp should light. Disconnect test lamp.
Figure 13:
2. Disconnect either positive or negative battery cable. Connect 12-volt test light between cable terminal and battery post (Figure 13).
3. If light glows, reconnect terminal to post for 5 seconds then repeat to ensure results.
Test Conclusions
^ Light Does Not Glow - No current drain.
^ Light Does Glow - Check individual circuits to locate cause of current drain. Underhood lamp, luggage compartment lamp, glove box lamp, reading or vanity mirror lamps are prime suspects.
Constant Current Drain Test (Message Center Equipped Vehicles)
1. Be sure all vehicle electrical circuits are turned OFF.
2. Disconnect either the positive or negative battery cable.
3. Connect an ammeter* (set at the highest current scale) between the cable terminal and the battery post.
4. Reduce to an appropriate scale for an accurate reading (allow 1 minute to stabilize).
*Use Rotunda digital volt-ohm meter No. 007-00001 or equivalent.
Test Conclusions
^ Drain current less than 0.05A - no current drain problems.
^ Drain current greater than 0.05A - check individual circuits to locate cause of current drain. Underhood lamp, luggage compartment lamp, glove box lamp, reading or vanity mirror lamps are prime suspects.
IMPORTANT NOTE:
When the Message Center is initially powered-up (after a battery disconnect), the Message Center "computer" may be energized for as long as one minute causing a .25A current draw before returning to the normal .010 -.012A current draw. Therefore, it is important to allow at least one minute to pass (after ammeter hook-up) before observing any current measurements.
NOTE: A voltmeter is sometimes used for this test but it will react to the very small normal drain caused by "always-on" electronic systems such as Starter Interlock, Anti-Theft Alarm, Illuminated Entry, etc., which are so small they cause no problem. The test lamp shows only drains which are large enough to cause a problem.
If any of the above conditions are found, the warranty cost for recharging the battery should be assigned to the specific causal factor - NOT THE BATTERY. Please refer to the claims coding section of the service labor time standards and the warranty and policy manuals.
OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: "INFORMATION ONLY"