1999 Ford Taurus Headlights stay on

Test the relays, my be sticking, if they are OK could be the switch, Gem Module,or if you have autolamps, the sensor. Or your hat is on top of the sensor?

AUTOLAMP SYSTEMS -1999 Ford Taurus SE
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MICRO ISO RELAY
1.Remove relay to be tested. Measure resistance between terminal No. 5 and all other terminals. See Fig. 4 . If all resistance reading are greater than 5 ohms, go to next step. If any resistance reading is 5 ohms or less, replace relay. 2.Measure resistance between terminals No. 3 and 4. If resistance is 5 ohms or less, go to next step. If resistance is greater than 5 ohms, replace relay. 3.Apply battery voltage and ground between terminals No. 1 and 2. Measure resistance between terminals No. 3 and 5. Resistance should be 5 ohms or less. Measure resistance between terminals No. 3 and 4. Resistance should be greater than 5 ohms. If resistance is not as specified, replace relay. If resistance is as specified, relay is okay at this time.
Fig. 4: Identifying Micro ISO Relay Terminals Courtesy of FORD MOTOR CO.

AUTOLAMP SYSTEMS -1999 Ford Taurus SE
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MINI ISO RELAY
1.Remove mini ISO relay. Measure resistance between appropriate relay terminals. See MINI ISO RELAY RESISTANCE SPECIFICATIONS table. See Fig. 3 . If resistance is as specified, go to next step. If resistance is not as specified, replace relay.
MINI ISO RELAY RESISTANCE SPECIFICATIONS Between Terminals No. Resistance 85 & 86 50-100 Ohms 30 & 87a 5 Ohms Or Less 30 & 87 Greater Than 10 K/Ohms 30 & 86 Greater Than 10 K/Ohms 86 & 87a Greater Than 10 K/Ohms 86 & 87 Greater Than 10 K/Ohms
2.Using a fused jumper wire, connect positive battery voltage to terminal No. 85. Using another jumper wire, ground terminal No. 86. Resistance should now be 5 ohms or less between terminals No. 30 and 87 and greater than 10 k/ohms between terminals 30 and 87a. If resistance is as specified, relay is okay at this time. If resistance is not as specified, replace horn relay.
Fig. 3: Identifying Mini ISO Relay Terminals Courtesy of FORD MOTOR CO.

AUTOLAMP SYSTEMS -1999 Ford Taurus SE
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NOTE: This test only applies to vehicles equipped with autolamps.
TEST B: HEADLIGHTS ALWAYS ON
1.Ensure headlight switch is off. Disconnect headlight switch connectors C2031 and C2032. If headlights are still on, go to next step. If headlights are off, replace headlight switch. 2.Remove autolamp headlight relay from engine compartment fuse box. If headlights are off, go to next step. If headlights are still on, repair short to voltage in Red/Yellow wire between headlight switch and multifunction switch. 3.Remove parking light relay from engine compartment fuse box. Measure resistance between ground and terminal No. 1 (White/Violet wire) at autolamp headlight relay socket C132. See Fig. 5 . If resistance is 5 ohms or less, go to next step. If resistance is greater than 5 ohms, replace autolamp headlight relay. 4.Reconnect all components. Disconnect light sensor/amplifier harness connector C2007. If headlights go off, replace light sensor amplifier. If headlights remain on, repair short to ground in White/Violet wire between light sensor/amplifier and autolamp headlight relay.

9/25/2008

In the owners manual, look for relays, in the index.