         
CS CHARGING SYSTEM DIAGNOSTIC PROCEDURES FOR ON-VEHICLE TESTING The following will provide a consistent, comprehensive procedure for on-vehicle CS alternator testing. VEHICLES WITH CHARGE INDICATOR LIGHTS (EXCEPT THOSE WITH PCM OR BCM CONTROL FEATURES) Switch ON, engine OFF, and light OFF 1. Connect your tester to the alternator and battery as per directions for your tester. Start engine and run at 2,000 to 2,500 RPM. If the alternator produces more than 50% of the rated output, the alternator is working properly. If alternator does not produce sufficient output, replace it and verify vehicle circuit operation in the following below. Engine OFF, ignition key OFF - Vehicle circuit operation: Detach harness connector from alternator. Ground the “L” terminal circuit of the harness connector with a 5 amp fused jumper lead. If the light comes on, circuit is operating properly. If light remains off, the circuit between the terminal and the ignition switch is open. The open may be something as simple as the bulb itself or other related harness connections. Engine running at 2000 to 2500 RPM, light ON 1. Stop engine, turn ignition switch to the “RUN” position. 2. Detach the harness connector at the alternator. If the light stays ON, check for a grounded “L” terminal circuit in the harness. If the light goes OFF, replace alternator. VEHICLES WITHOUT CHARGE INDICATOR LIGHTS (AND/OR THOSE WITH PCM OR BCM CONTROLLED ALTERNATORS) 1. Install scan tool and start engine. Locate alternator control parameter on scan tool data list. If alternator command is “OFF” or “DISABLE”, refer to vehicle service information. (Note: “DISABLE” means the PCM has disabled alternator operation, determine possible fault or faults in non-alternator related systems or circuits.) If alternator command is “ON” or “ENABLED”, continue to step 2. 2. Detach wiring connector from alternator. With switch “ON”, engine “OFF” connect voltmeter from ground to “L” terminal (if present) and to the “L” terminal (if present). The voltage reading should be close to battery voltage. A zero reading indicates an open or grounded circuit. After correcting any problems found in the wiring harness, recheck alternator for output. See reverse side VEHICLES IN WHICH CHARGING SYSTEM SEEMS TO BE OPERATING NORMALLY OR OVERCHARGING (WITH OR WITHOUT PCM OR BCM FEATURES) 1. Connect an ammeter to the alternator output terminal (or inductive probe) and a voltmeter to the battery. 2. With the alternator harness attached, run the engine to 2000 to 2500 RPM and measure voltage across the battery. If the reading is above 16 volts, replace the alternator. At 2000 to 2500 RPM, turn on electrical accessories and load the battery with a carbon pile tester to obtain maximum amp output. If output is within 15 amps of rated output, the alternator is working properly. If amperage is not within 15 amps of rated output, recharge or replace battery and recheck output of alternator. 
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