Charging System - Diagnostic Procedure Revision
86ford18 Article No. 86-9-2CHARGING SYSTEM DIAGNOSTIC PROCEDURE - REVISED
FORD 1986 TAURUS; 1987 MUSTANG
LINCOLN-MERCURY 1986 SABLE
LIGHT TRUCK 1986 AEROSTAR; 1987 F SERIES
The charging system function is now dependent on electrical continuity at the charge indicator light.
The charging system may become inoperative when any of the following conditions exist:
1. The charging indicator bulb and socket assembly is not properly seated, or over-rotated within the socket hole during installation.
2. The charging indicator bulb fails and the socket resistor is not present.
3. The charging indicator bulb and socket assembly is not present.
The existing charging system procedures have been revised to cover the possibility of the three conditions described above (see 31-01-4).
Additional Corrections to Diagnostic Procedure (see 31-01-9)
Page 31-01-9 of the Taurus/Sable Shop Manual has been revised to correct the voltmeter lead callouts (polarities reversed), and Step 3 has been reworked.
OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: "INFORMATION ONLY"
Indicator Lamp System
Normal Charge Indication The new integral Alternator Regulator (IAR) has a circuit in the regulator that will indicate a high battery voltage condition. With the IAR system, three conditions can cause the charge indicator lamp to come on during vehicle operation:
1. No alternator output: Damaged alternator, regulator or wiring.
2. Over voltage correlation: Shorted alternator rotor, regulator or wiring.
With ignition switch in the OFF position: Charge indicator battery symbol lamp is off. With ignition switch in the RUN position (engine not running): Charge indicator (alternator) lamp is on. With ignition switch in the RUN position (engine running): Charge indicator (alternator) lamp is off.
EVR System
1. If charge indicator lamp does not come on with the ignition key in RUN position and engine not running, check the I wiring circuit (ignition switch to regulator I terminal) for open circuit or burned out charge indicator lamp.
2. If charge indicator lamp does not come on, disconnect wiring plug connector at regulator and connect a jumper wire from the I terminal of regulator wiring plug to negative battery post cable clamp.
3. Charge indicator lamp should go on with ignition key turned to RUN position.
4. If charge indicator lamp does not go on, check for presence of bulb socket resistor. If resistor is missing, replace bulb socket. If resistor is present, check for contact of bulb socket leads to the flexible printed circuit. If good, check indicator bulb for continuity and replace if burned out.
5. If bulb and socket are good and socket leads are in contact with the flexible printed circuit, open circuit exists between ignition switch and regulator.
6. Check 5OO ohm resistor across indicator lamp.
IAR System
1. If charge indicator lamp does not come on, disconnect wiring connector from regulator and connect a jumper wire from wiring connector I terminal to battery negative post cable clamp.
2. Turn ignition to RUN position with engine off. If indicator lamp does not light, check for presence of bulb socket resistor. If resistor is missing, replace bulb socket. If resistor is present, check for contact of bulb socket leads to the flexible printed circuit. If good, check indicator bulb for continuity and replace bulb if burned out. If bulb checks good, perform regulator I circuit test.
3. If indicator lamp does light, remove jumper wire and reconnect wiring plug to regulator. Connect voltmeter negative lead to battery negative post cable clamp and contact voltmeter positive lead to regulator A terminal screw. Battery voltage should be indicated. If battery voltage is not indicated, service A circuit wiring.
TESTING (Continued)
Regulator S and/or I Circuit
EVR System
1. Disconnect regulator wiring plug and install jumper wire between A and F terminals.
2. With engine idling and negative voltmeter lead connected to battery ground terminal, connect positive lead of voltmeter Rotunda Number 014- 00407, to S terminal and then to I terminal of regulator wiring plug. Voltage of S circuit should read approximately one-half of I circuit. If voltage readings are normal, remove jumper wire, replace regulator and connect wiring plug. Repeat Load Test.
3. If no voltage is present, the wiring is at fault. Service the faulty circuit.
4. Remove jumper wire from regulator wiring plug and connect wiring plug to regulator. Repeat Load Test. Refer to illustration of jumper wire connections in Under Voltage, External Voltage Regulator System.
IAR System
1. Disconnectthe wiring plug from the regulator. Connect a jumper wire from the regulator "A" terminal to the wiring plug "A" lead. Add a jumper wire from the regulator "F" screw to the alternator rear housing.
2. With the engine idling and the voltmeter, Rotunda Number 014-00407, negative lead cone to the alternator rear housing, connect the voltmeter positive lead to the "S" terminal and then to the "I" terminal of the regulator wiring plug. The voltage at the "S" circuit should read approximately one-half that of the "I" circuit. If voltage readings are normal, remove the jumper wire. Replace the regulator and connect the wiring plug to the regulator. Repeat the load test.
3. If no voltage is present, remove the jumper wires and service the faulty wiring circuit or alternator.
4. Connect the voltmeter positive lead to the positive battery terminal. Connect the wiring plug to the regulator. Repeat the Load Test.