Daytime Running Lights

October 22, 2007

The Internet is full of discussions among car owners about DRLs, as they are known among the acronym set. American truck owners desperately want to disconnect their DRLs for reasons that would boggle the mind. My favourite was the Toyota owner who waits for the train in the early morning with his engine running to keep the truck warm. He doesn’t want to disturb the suburban residents near the station with his lights. Another serious off-roader worries that he will blind the track marshalls if he flashes his lights in their eyes at a critical point on the course. About one in ten fears that the increased use from daylight running will wear his lights out. Two contributors seriously discussed the risk of frying their trucks’ wiring by operating their lights in daytime. Many worry that their V8s will get worse gas mileage from producing all that electricity.

Canadian owners, on the other hand, desperately want to find out how to install the DRLs so that they can register their new vehicles before the temporary plates run out. Most will be happy merely to pass the test, but the owners of Honda S2000 models want the ultimate in DRL-cool, the 60% dimming effect. This seems to require a great deal of experimentation and not a few mishaps involving lost high beams, if one is to believe today’s posts.

The Hamsar module’s instructions called for the green wire to be fastened with cable ties next to a spark plug wire to draw impedence from it and activate the module. My truck has no spark plug wires, just little solid state things sitting where the plugs should be. I asked for help on two Toyota forums. None was forthcoming except for one moderator who stated that any module which tried to take power from a spark plug should definitely not be installed. In desperation I asked the readers of Yesterday’s Tractors — a collection of uncommonly smart and helpful people.

In a few minutes a guy named Vern sent me an e-form for a customer inquiry from Hamsar, the Markham company which produces the DRL control unit. The response came inside fifteen minutes. Caroline, the company rep, suggested that I connect the green wire to any circuit activated by the ignition switch. A careful examination of the instructions revealed that yes, hard-wiring the green wire to the oil pressure sender would also do the job.

A brave dive under the truck turned up the missing oil pressure sender, and I was even able to track it up to the surface of the engine where I exposed the green and yellow wire after knawing through three levels of protection. The downloaded Toyota manual gave me wire colours and locations. Mind you, it took a week of reading.

All that remained was to hook the thing up. The little clips which come from Hamsar are dreadfully dull. I broke the first one without denting the headlight wire. Fortunately I had several of the splicing clips left over from a trailer-repair job, and they went right on.

Bet held the light as I did my usual chaotic wiring job and then held her breath as I touched the green wire to the battery terminal. The lights all came on. I disconnected. They went off four seconds later. It works! I clipped the green wire to the oil pressure sender wire and fired her up. Oil pressure light still works. The lights come on by themselves as soon as the truck starts.

Flushed with success and telling myself it only has to work once for the inspection, I quickly stuffed the DRL unit down behind the battery and started up a couple of more times. High beams work normally. All lights come on at full intensity — had I bought a more sophisticated Hamsar unit they’d only come on at 60%, but this one was on the shelf, and what did I know?

Anyway, it works. The truck is now ready for the next step once the package comes from the Registrar of Imported Vehicles. Cool!


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