Charging System - Checks
84jaguar01Date.....SEPTEMBER, 1984
ITEM: J84/34
SUBJECT: CHARGING SYSTEM CHECKS
MODEL: XJ6 & XJ-S WITH LUCAS A-133 75 AMP ALTERNATOR
Carry out checks using Lucas 511, Sun VAT 40 or equivalent tester.
For charging system diagnosis, always check Battery and Alternator.
VISUAL CHECKS
Battery - Examine for cracked, deformed, leaking case, loose or corroded terminals, electrolyte level and state of charge indicator (Delco).
Vehicle Charge Indicator Light:-
^ Should be off with ignition off; if on, suspect bad alternator diode.
^ Should be on with ignition on; if off, suspect chargeindicator circuit or bulb.
^ Should be off with engine running; if on, suspect poor alternator output or loose belt.
Alternator Belt - If glazed, cracked or worn - Replace. If loose - set to correct tension.
BATTERY TEST
^ All accessories and lights off.
^ Attach tester. (Follow tester instructions.)
^ Load battery to 300 AMPS for 1 second (to remove surface charge).
^ Read no load battery voltage:-
^ Below 12.4V, charge battery and retest.
^ Load battery to 250 AMPS Delco, 200 AMPS Lucas MF3 for 15 seconds and read voltage:-
^ 9.6V or above - battery serviceable.
^ Below 9.6V - replace battery (battery temperature affects voltage).
If defective battery is replaced, retest and test alternator.
ALTERNATOR TEST (Lucas A133 75 AMP)
^ All accessories and lights off.
^ Start engine.
^ Attach tester. (Follow tester instructions.)
^ Run engine at 2000 RPM.
^ Adjust load to get maximum amperage: -
^ (Voltage must not go below 12 volts.)
^ Amperage must be 67.5 - 75 AMPS.
^ If incorrect, check regulator or test for current drain.
REGULATOR TEST
^ Tester still attached, engine at 3000 RPM.
^ Reduce load to Zero (load indicator light out).
^ Allow to run until charging below 10 AMPS.
^ Voltage between 13.6 - 14.4.
^ If incorrect, replace regulator and retest.
CURRENT DRAIN TEST
If battery goes dead, and battery and alternator check okay, or alternator test shows low amperage:-
^ Set ammeter to lowest scale and connect to battery ground cable.
^ Ignition and all electrical loads off.
^ Ammeter should be Zero (may be slight reading from trip computer - milliamps only).
^ If incorrect, remove fuses one by one until ammeter reads Zero.
^ Ignition on - all other electrical loads off.
^ Ammeter should be 5-6 AMPS.
^ If more, remove fuses one at a time to pinpoint trouble circuit.