Project Civic: DRL Fix

In Canada, DRL or Daytime Running Lights are mandatory on newer vehicles. This system powers the headlights as soon as you start the engine.

One day, while pulling out of the driveway, one of the headlights for the Civic did not seem to be functioning. A quick check of the fuse and the bulb revealed they were both ok. A few minutes later, the headlight began to function again so it was dismissed as just a temprary glitch. The problem eventually resurfaced. This time the DRL trouble light on the gauge cluster remain lit and most of the time there was a persistent buzzing sound coming from behind the glove compartment.

Switching on the headlights using the steering column mounted stalk switch powers on the headlights normally. Obviously there was nothing wrong with the headlights themselves. The buzzing is coming from the headlight relays (Relay-RC5102) and replacing them with new relays ($25 each) did not eliminate the buzzing or fix the DRL issue. The only next logical place to check is the DRL module.

A quote from a Honda parts store had the DRL module (RZ-0126) for more than $200. That seemed quite pricey for a relay box. A google search netted a few suggestions for DRL troubleshooting.

Step one is locating the DRL module and removing it. The relay is located above the clutch pedal on the 7th generation civic coupe. Look for the plastic grey box pictured below, with the characteristic BLUE connector. You remove it by pushing up until it slides off the connector.


(The DRL module removed from the Civic)

Using a small screwdriver, the cover for the DRL relay was carefully pryed off. There are no screws to remove and the circuit board simply slides off.


(A few dozen capacitors and resistors and two relays to handle the current from the headlamps. These relays are correctly rated for the 55W low beams so this is another obvious reason not to use those 80-100 Watt bulb replacements)

The underside of the circuit board will reveal the problem areas. What you need to watch for are cracks or any surface that does not look smooth. Honda covered the board in grease, probably as a rust preventative measure. Any crack or loose connection will usually result in a "burnt" looking area around the solder joints. Fixing them is as simple as heating up the joint with a soldering iron to re-melt the old solder then apply some new solder to the joint as needed.


(The joints with the "glazed" look or burnt area are the ones that need to be resoldered.

Once resoldering is completed. The last step is just reassembling the DRL module and reattaching it to the blue plug. A quick test immediately yielded positive results and the DRLs have been working fine ever since.

Update: This fix has been shown to be successful on civics, preludes, and accords, of varying years. The modules all appear to be the same, or very close. Honda placed them underneath the dash or behind the glove compartment and is usually suspended by a single hanger. Constant vibration causes the solder points to crack and then once power is applied to the other components, the lose connection tends to short other parts.