Circuit Description
The daytime running lights (DRL) are controlled by the body control module (BCM). The BCM grounds the DRL relay control circuit in order to energize the DRL relay coil. This action places the RH and LH headlamps in series with each other with the DRL relay providing the ground path and the RT HDLP fuse providing battery positive voltage. The BCM monitors the low and high beam circuits to ensure that the DRLs are operating properly. If the BCM senses that the DRLs are not operating properly, DTC B2600 is set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B2600 Daytime Running Lamp Control 1 Circuit
Conditions for Running the DTCs
| • | The headlamp switch is OFF. |
| • | The park brake is unapplied. |
| • | The transaxle is in gear. |
Conditions for Setting the DTC
One or more of the following conditions are present:
| • | The DRL relay control circuit is open. |
| • | The DRL relay output circuit is open. |
| • | The right headlamp battery positive voltage circuit is open. |
| • | The left headlamp battery positive voltage circuit is open. |
| • | The DRL relay ground circuit is open. |
Action Taken When the DTC Sets
| • | The BCM turns OFF the DRL relay control for the remainder of the ignition cycle. |
| • | The SERVICE indicator illuminates. |
Conditions for Clearing the DTC
| • | The conditions for setting the DTC are no longer present. |
| • | A history DTC clears after 100 malfunction free ignition cycles. |
| • | The BCM receives the clear code command from the scan tool. |
Diagnostic Aids
| • | Check both the LH and RH headlamps for proper operation. |
| • | Check both the LH and RH HDLP fuses. |
| • | Diagnose all other DRL DTCs before DTC B2600. |
| • | If the DTC is a history DTC, the problem may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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DTC B2600 will disable the DRL. If the DRLs are operational the code is not current. If DTC B2600 is not current, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
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This condition indicates that there is a short to voltage in the headlamp high beam signal circuit or the headlamp low beam signal circuit.
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This step verifies normal headlamp operation.
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This step checks for battery positive voltage at the coil side of the DRL relay.
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This step verifies that the BCM is providing ground to the coil side of the DRL relay.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
Do the DRLs illuminate? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | |
Are the headlamps pulsing ON and OFF? | Go to Step 14 | Go to Step 4 | |
Do the headlamps operate properly? | Go to Step 6 | Go to Step 5 | |
5 | Are both the high beam and low beam headlamps on one side inoperative? | Go to Step 15 | Go to Step 16 |
6 | With a scan tool, command the DRL relay ON and OFF . Do you hear a click when you command the DRL relay ON and OFF? | Go to Step 9 | Go to Step 7 |
Does the test lamp illuminate? | Go to Step 8 | Go to Step 17 | |
Does the test lamp illuminate? | Go to Step 12 | Go to Step 11 | |
9 | Test the ground circuit of the DRL relay for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 20 | Go to Step 10 |
10 | Test the headlamp high beam signal circuit and the headlamp low beam signal circuit for an open or high resistance between the headlamp switch assembly and the body control module (BCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 20 | Go to Step 13 |
11 | Test the DRL relay control circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 20 | Go to Step 13 |
12 | Inspect for poor connections at the DRL relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 20 | Go to Step 18 |
13 | Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 20 | Go to Step 19 |
14 | Repair the short to voltage in the headlamp high beam signal circuit or the headlamp low beam signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 20 | -- |
15 | Repair an open, high resistance, or short to ground in the supply voltage circuit of the inoperative headlamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 20 | -- |
16 | Repair an open or high resistance in the headlamp high beam signal circuit or the headlamp low beam signal circuit of the inoperative headlamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 20 | -- |
17 | Repair an open, high resistance, or short to ground in the battery positive voltage circuit of the DRL relay's coil side. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 20 | -- |
18 | Replace the DRL relay. Did you complete the replacement? | Go to Step 20 | -- |
19 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 20 | -- |
20 |
Does the DTC reset? | Go to Step 2 | System OK |
