Charging System - Generator & Regulators: Diagnosis Ford Taurus IV

TROUBLE SHOOTING

Note. Also see TROUBLE SHOOTING article in GENERAL INFORMATION.

PARASITIC DRAW TEST

Connect ammeter to negative battery cable according to tool manufacturer's instructions. With all accessories off, doors closed and key out of ignition, current drain should be less than 50 milliamps. To locate the cause of current drains greater than 50 milliamps, remove fuses one at a time until current draw is within specification. Repair appropriate circuit, and retest system operation.

GENERATOR LOAD TEST

Ensure drive belt is in good condition. Replace belt as necessary. If belt is okay, connect charging system load tester in accordance with manufacturer's instructions. Start and run engine at 2000 RPM and apply load until generator output levels off. Generator output should be at least 58 amps at 2000 RPM.

GENERATOR NO-LOAD TEST

Connect voltmeter positive lead to B+ terminal on generator and negative lead to ground. Start and run engine at 2000 RPM with no electrical load (all accessories off). Read voltmeter when voltage stabilizes. Voltage should be 13-15 volts.

TEST A: SYSTEM OVERCHARGES (MORE THAN 15 VOLTS)

1. Disconnect generator 3-pin connector. Turn ignition switch to RUN position. Measure voltage drop in circuit "A" by connecting voltmeter positive probe to generator connector terminal "A" (Orange/Light Blue wire). Connect voltmeter negative probe to battery positive terminal. If voltage is less than .25 volt, go to next step. If voltage is .25 volt or greater, repair high resistance in Orange/Light Blue wire. Also inspect fuse No. 126 (30-amp) in Battery Junction Box (BJB) for high resistance. See «WIRING DIAGRAMS»(ref-37886-S40494971862001011000000) .
2. Inspect ground connections between battery and engine. Ensure generator mounting surfaces are clean and bolts are secure. If all grounds or mounting surfaces are not okay, repair as necessary and retest system operation. If grounds and mounting are okay, replace generator and retest system operation. See «GENERATOR»(ref-37886-S29990570682001011000000) under REMOVAL & INSTALLATION.

TEST B: CHARGE WARNING INDICATOR ON WITH ENGINE RUNNING

1. Measure voltage between generator B+ terminal (component side) and ground. If battery voltage is present, go to next step. If battery voltage is not present, repair open in Yellow/White wire. Retest system operation. See «WIRING DIAGRAMS»(ref-37886-S40494971862001011000000) .
2. Disconnect generator 3-pin connector. Measure voltage between connector terminal "A" (Orange/Light Blue wire) and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Battery Junction Box (BJB) fuse No. 126 (30-amp). Replace fuse as necessary. If fuse is okay, repair open in Orange/Light Blue wire. See «WIRING DIAGRAMS»(ref-37886-S40494971862001011000000) . Retest system operation.
3. Disconnect generator 3-pin connector. With ignition on, engine off, measure voltage between generator 3-pin connector terminal "I" (Light Green/Red wire) and ground. If battery voltage is present, go to next step. If battery voltage is not present, repair open in Light Green/Red wire. See «WIRING DIAGRAMS»(ref-37886-S40494971862001011000000) . Retest system operation.
4. Reconnect connectors. Start engine. Turn on headlight and set blower motor to high position. Run engine at 2000 RPM, and measure voltage drop in B+ circuit by connecting voltmeter positive lead to generator terminal B+ (Yellow/White wire) and negative lead to battery positive terminal. If voltage is less than .5 volts, replace generator. See «GENERATOR»(ref-37886-S29990570682001011000000) under REMOVAL & INSTALLATION. If voltage is greater than .5 volts, repair open or high resistance in Yellow/White wire. See «WIRING DIAGRAMS»(ref-37886-S40494971862001011000000) .

TEST C: CHARGE WARNING INDICATOR ON WITH ENGINE RUNNING, SYSTEM INCREASES VOLTAGE

Disconnect generator 3-pin connector. With ignition switch in RUN position, observe charge warning indicator. If charge warning indicator illuminates, repair short to ground in Light Green/Red wire. Retest system operation. If charge warning indicator does not illuminate, replace generator. See GENERATOR under REMOVAL & INSTALLATION.

TEST D: CHARGE WARNING INDICATOR INOPERATIVE

Disconnect generator 3-pin connector. With ignition on, engine off, connect a fused (15-amp) jumper wire between generator 3-pin connector terminal "I" (Light Green/Red wire) and ground while observing charge warning indicator. If charge warning indicator illuminates, replace generator. If charge warning indicator does not illuminate, check indicator bulb and replace as necessary. If bulb is okay, repair high resistance in bulb socket or Light Green/Red wire. See WIRING DIAGRAMS . Retest system operation.

TEST E: CHARGE WARNING INDICATOR FLICKERS OR IS INTERMITTENT

1. Inspect battery, Battery Junction Box (BJB), Central Junction Box (CJB) and generator connectors for loose, corroded or damaged connections. Repair as necessary and retest system operation. If all connections are okay, go to next step.
2. Start engine. Wiggle appropriate fuses and fusible links while observing charge warning indicator. If charge warning indicator does not flicker, go to next step. If charge warning indicator flickers, repair appropriate loose connection and retest system operation.
3. Turn ignition switch to OFF position. With generator connectors connected, backprobe generator 3-pin connector terminal "A" (Orange/Light Blue wire) with a fused (15-amp) jumper wire. Connect other end of jumper wire to battery positive terminal. Start engine and observe charge warning indicator. If charge warning indicator does not flicker, repair loose connection in circuit between battery and generator 3-pin connector. See «WIRING DIAGRAMS»(ref-37886-S40494971862001011000000) . Retest system operation. If charge warning indicator flickers, replace generator. See «GENERATOR»(ref-37886-S29990570682001011000000) under REMOVAL & INSTALLATION.