Pinpoint Test E: The Low Beams Are Always On
Headlamps
Pinpoint Tests
Pinpoint Test E: The Low Beams Are Always On
Refer to Wiring Diagram Set 85, Headlamps for schematic and connector information. Diagrams By Number
Normal Operation
When the headlamp switch is placed in the HEADLAMPS ON position, voltage is provided to the low beam relay coil, the Instrument Cluster (IC) and the Generic Electronic Module (GEM). When the low beam relay is energized, voltage is provided through the Battery Junction Box (BJB) fuses 25 (10A) and 23 (10A) to the headlamps.
On vehicles equipped with Daytime Running Lamps (DRL), the DRL system provides voltage to the low beams and to the parking lamps when the ignition switch is in the RUN position. When the DRL relay is energized, the DRL relay supplies voltage through a resistor wire to the low beams and supplies voltage on a separate circuit through the Central Junction Box (CJB) fuse 168 (10A) to the headlamp switch. The voltage passes through the headlamp switch to the parking lamps.
- DTC B1312 (Lamp Headlamp Input Circuit Short to Battery) - an on-demand DTC that sets when the IC detects a short to voltage from the headlamp switch-to-low beam relay coil circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Low beam relay
- Headlamp switch
- GEM
- IC
PINPOINT TEST E: THE LOW BEAMS ARE ALWAYS ON
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
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E1 VERIFY THE LOW BEAM RELAY OUTPUT
- Ignition OFF.
- Disconnect: Low Beam Relay.
- Ignition ON.
- Do the headlamps continue to illuminate?
Yes
GO to E2.
No
GO to E7.
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E2 CHECK THE LH HEADLAMP VOLTAGE SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE
- Disconnect: BJB Fuse 25 (10A).
- Does the LH headlamp continue to illuminate?
Yes
REPAIR circuit 15S-LE16 (GN/OG) for a short to voltage. TEST the system for normal operation.
No
GO to E3.
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E3 CHECK THE RH HEADLAMP VOLTAGE SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE
- Disconnect: BJB Fuse 23 (10A).
- Does the RH headlamp continue to illuminate?
Yes
REPAIR circuit 15S-LE23 (GN/WH) for a short to voltage. TEST the system for normal operation.
No
If not equipped with DRL, REPAIR the low beam relay output circuit for a short to voltage. TEST the system for normal operation.
If equipped with DRL, GO to E4.
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E4 CHECK THE DRL RELAY OUTPUT
- Disconnect: DRL Relay.
- Do the parking lamps continue to illuminate?
Yes
GO to E5.
No
GO to Pinpoint Test W. Pinpoint Test W: The Daytime Running Lamps (DRL) Are On With The Ignition Switch Off
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E5 ISOLATE THE PARKING LAMP CIRCUITRY FOR A SHORT TO VOLTAGE
- Disconnect: Headlamp Switch C205.
- Do the parking lamps continue to illuminate?
Yes
GO to Pinpoint Test O. Pinpoint Test O: The Parking, Rear Or License Plate Lamps Are On Continuously
No
GO to E6.
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E6 ISOLATE THE SHORT TO VOLTAGE
- Connect: BJB Fuse 25 (10A).
- Connect: BJB Fuse 23 (10A).
- Disconnect: CJB Fuse 168 (10A).
- Do the headlamps continue to illuminate?
Yes
REPAIR the DRL/low beam relay output circuit for a short to voltage. TEST the system for normal operation.
No
REPAIR circuit 15S-LE29 (GN/BK) for a short to voltage. TEST the system for normal operation.
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E7 CHECK THE LOW BEAM RELAY
- Substitute a known good relay.
- Do the headlamps continue to illuminate?
Yes
REMOVE the known good relay. GO to E8.
No
REMOVE the known good relay. INSTALL a new low beam relay. TEST the system for normal operation.
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E8 CHECK THE HEADLAMP SWITCH
- Ignition OFF.
- Connect: Low Beam Relay.
- Disconnect: Headlamp Switch C205.
- Ignition ON.
- Do the headlamps continue to illuminate?
Yes
GO to E9.
No
INSTALL a new headlamp switch. REFER to Headlamp Switch Service and Repair. TEST the system for normal operation.
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E9 CHECK THE GEM
- Ignition OFF.
- Disconnect: GEM C201b.
- Ignition ON.
- Do the headlamps continue to illuminate?
Yes
GO to E10.
No
GO to E11.
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E10 CHECK THE IC
- Ignition OFF.
- Disconnect: IC C220a.
- Ignition ON.
- Do the headlamps continue to illuminate?
Yes
REPAIR the headlamp switch output circuit to the low beam relay coil for a short to voltage. TEST the system for normal operation.
No
GO to E12.
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E11 CHECK FOR CORRECT GEM OPERATION
- Ignition OFF.
- Disconnect all the GEM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the GEM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new GEM. REFER to Body Control Systems. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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E12 CHECK FOR CORRECT IC OPERATION
- Ignition OFF.
- Disconnect all the IC connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the IC connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new IC. REFER to Instrument Panel, Gauges and Warning Indicators. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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