DIY: converting bad DRL system into conventional one

[Doctor J]

These statements are reflecting my own opinion and have nothing to do with repair description described in following article.
The above problem is a result of inferior circuit design and quick pushing of the prototype into the production without necessary testing. The domestic cars demonstrating inferior assembly workmanship, the Japanese cars are suffering due to the component design flaws and materials of budget quality. This can be supported by the high number of electrical system related recalls (2007-08 Honda Fit). From the experience: my friend’s 81 Oldsmobile Delta 88 had only 2 chassis electrical defects (the key reminder buzzer and the fuel level gage). My 79 Supra had mechanical problem with windshield wiper motor and that about it. My 87 Camry required starter relay, instrumental panel circuit board and automatic seat belt repairs. It seems like 99 Corolla shows electrical problems at much earlier age. Thus I will be busy doing car repairs

1999 Toyota Corolla DRL to standard lighting system conversion
While doing accelerator cable adjustment on 99 Corolla I was asked by the owner to investigate two ongoing electrical issues:
• The radiator cooling fans are running all time with ignition on
• The parking lights stays on with switch in off position; turning switch on and off few times solves the problem.
The first problem has been caused by stuck a/c pressure sensor, while the parking lights problem attributed to the DRL module failure. After reading about possible repairs and considering the cost of the new DRL module ($200), I decided to convert the DRL system into the conventional one.
The following article will provide directions how to do it.

The following actions will assure that the lighting system will work correctly without DRL relay in the conventional way as described:
• The switch will turn on the parking, low and high beams (steady on and “flash” functions)
• The parking brake on and high beam on indicators will be working

The procedure requires experience in automotive electrical repair, ability to read electrical schematics and 22 gage wire splicing skills.

Tools and materials required:
Analog multimeter
Screwdriver, Phillips
Screwdriver, Phillips Stubby
Screwdriver flat small (to pry the covers apart)
Socket 10 mm with ratchet driver and
10 mm wrench combo (to remove glove box and negative cable from the battery)
Wire cutters
Wire strippers 16 to 22 gage
Soldering iron, rosin core solder, 1/8 shrink wrap, electrical tape, cigarette lighter and ceramic tile (or equivalent nonflammable heat insulating material)
4 ¼ inch spade crimp-on terminals to make 2 jumpers, 2 feet 16 or 18 gage wire insulation rated to 90-100 degrees C (I used the white one so you can see it easier)
Wire crimping tool
Light and mirror
Parts to be permanently removed from the car: DRL module and DRL SPST relay

Procedure:
1. Disconnect and remove the battery
2. Remove right kick panel and glove box assembly
3. Using stubby Phillips screwdriver, remove the DLR module with bracket
4. Unplug the module and put it aside
5. Cut from the connector and solder together the following wires:


16 and 17 (LGHT GRN and LIGHT GRN-BLK) for tail light relay control
19 and 2 (both RED-WHT) for head light relay control
20 and 3 (WHT- RED and RED-YEL) for low beam/ High beam relay control;
4 and 14 (RED-YEL and RED BLK) for “parking brake on” indicator
21 and 18 (RED-GRN and RED-BLK) for “high beam on” indicator



Strip the insulation 5/16” from the end, twist and solder wires together, then insulate the soldering connections with shrink wrap. (As you can see, I should cut the wires closer to the plastic connector to make soldering and insulating job easier)




6. Remove the DLR SPST relay from the box near the washer reservoir and install the jumper as illustrated into the cavities 1 and 2 /




7. Unbolt fuse/ relay boxes located next to the battery and air cleaner
8. Open the bottom cover of the larger box containing high beam fuses
9. Solder one end of the wire (white one the picture) to the RED-YEL wire; guide wire out of the box and close its bottom cover (see the picture below)



10. Open the bottom cover of the smaller box containing DRL 7.5 a fuse
11. Cut the RED wire coming out of that fuse,



12. Solder the “fuse” end of the RED wire to the WHITE wire that you guided out of the larger box; insulate free end of the RED wire



The above steps (8 to 12) will allow the high beam indicator to function by connecting the part of DRL SPST relay control circuit to the high beam feed wire as shown on the diagram



13. Close the box cover and attach both boxes to the car.
14. Install and connect the battery
15. Check the operation of the parking lights and headlights (high and low beams & flash mode) - no key required
16. Set the multimeter to DC volts; insert the positive probe into the cavity number 4 on the removed DRL relay footprint. Connect negative probe to the good ground. Check for be 12 volts presence when headlight switch is in High Beam or Flash mode; NO voltage must be indicated in parking lights or Low beam position of the switch.
17. If so, remove the meter, install the jumper between cavities number 3 and 4 and verify that the High beam indicator light is on when the switch is in High beam or Flash position



18. Turn ignition on and check the operation of hand brake "on" indicator
19. Install the glove box and kick panel cover
Repair is complete. Thank you for reading

[Bitter]

Root cause of the damaged DRL module is a poor ground, usually its in the big ground 'splice' which is too light to handle all the power through it. IIRC its located up above the drivers outer kick panel and is a large group of white/black wires.

[Doctor J]

I've checked for the voltage drop across the white jumper terminal @ DRL SPST relay footprint and negative battery post with high beams for high resistance,and got about 0.15 Volts, so the high resistance of the ground point may not be an issue in that case. The conversion done this way is still cheaper then $200 module plus or the inconvenience of discharged battery due to the "out of control" lights.

[Bitter]

Originally Posted by Doctor J

I've checked for the voltage drop across the white jumper terminal @ DRL SPST relay footprint and negative battery post with high beams for high resistance,and got about 0.15 Volts, so the high resistance of the ground point may not be an issue in that case. The conversion done this way is still cheaper then $200 module plus or the inconvenience of discharged battery due to the "out of control" lights.

What I've see first hand on several cars in the shop for the same symptoms were all fixed by a new module and repairing the burned ground. the ground is actually about 8 or 10 wires that all clip onto a 'comb' which grounds to the body, so when the attachemnt to the body goes bad circuits ground through other circuits...like the radiator fans pull ground through the head lights via the DRL module, or the fuel injectors pull power through the bulbs so the engine dies when the lights are turned on or DRL comes on.

if you take all the ground wires, solder them into a bundle, solder an 8 gauge wire, solder an eyelet, and ground it to bare metal the problem goes away forever (and well replace the burned module). Open the module, it will be burned across several diodes on the board.

[Doctor J]

The ground problem in headlight circuit will show up as headlights dim when other circuits will be turned on (which is often confused with the low battery). I need to check the diagram for that particular car, but I believe that the EFI computer is grounded to the intake manifold, so if the engine dies after the headlight are turned on, I would check the EFI ECU power supply and the engine to the battery negative post connector.
Unfortunately, finding the replacement module on Sunday afternoon, especially if car needed next morning is problematic, so cutting and splicing few wires (and checking the ground point as you suggested) can be the most effective repair. The DRL systems as well as automatic seat belts are “babysitting stuff” which makes car operation illegal and unsafe in event of the system failure

[Bitter]

Trust me on this, open the module up, slide the board out, post a photo.

IIRC the splice that burns is like 201 on the wiring diagrams, its been about a year since I had to do one of these.

[Doctor J]

I should send this module to the "specialists" who designed and bulid that inferior stuff.

[FRANKGBACOA]

driving from work my low beams turned off and no high beams either. i replaced the headlight switch and nothing, went ahead and took the drl box out and it seems fine( no burnt smell or signs) also none of the fuses related to headlights have power coming in, the only one that has power is the 7.5a drl in the small fuse box on the drivers side. On the big fuse box in the drivers side the relay has power in one of the small prongs(the one closer to the engine) and also have power on the big prong close to the fender and when i actuate the relay with my hands it gives me a little power on the small prong close to the fender.on the passenger side's relay box i have power when i actuate the relay on the drivers side but still no lights whatsoever. read a lot about testing the light sensor on top of the dash, the drl box, but still no headlights.thanks in advance