Daytime Running Light System Control Fault
The B0070 code means the vehicle's onboard diagnostic system has detected: Daytime Running Light System Control Fault. This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $50 - $350 (parts and labor)
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Common Symptoms
- Both DRLs not functioning
- DRL warning light on dashboard
- Headlights work but DRLs do not
- DRL system not responding
Probable Causes (Ranked by Likelihood)
- Failed DRL control module or relay Very High
- Faulty ambient light sensor input High
- BCM DRL control circuit failure Moderate
- CAN bus communication error Low
Step-by-Step Diagnostic Procedure
-
Check DRL relay and fuse
-
Test ambient light sensor signal
-
Scan BCM for DRL system codes
-
Inspect CAN bus to DRL controller
Frequently Asked Questions
Can I disable the DRL system?
Some vehicles allow it via scan tool, but it is not recommended.
Why do both DRLs fail at once?
Usually a shared control circuit issue.
Does parking brake affect DRLs?
On many vehicles, DRLs disable when the parking brake is engaged.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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