Any Mechanics ?- Problem with My Daytime Running Lights

[james t kirk]

Here's the Deal.

The Daytime Running Lights on my car have an intermittant problem. Sometimes they work fine.

Sometimes, only the left one works, and it operates on full intensity (high beam), the right one is dark.


The DTRLs are simply the High Beams wired in series so that they operate at half intensity. (The voltage effectively is cut in half.)

Both High Beams operate as normal when activated normally. (So the bulb is not burned out. Since they are wired in series, if one bulb was to burn out, neither would work.)

When the problem occurs, the Left DTRL operates at High Beam intensity, the right one is dark.

Then, for no reason, they will begin operating as normal. No amount of high beaming, or on/off of the headlights or parking lights will result in normal operation occuring.

I have looked at the Service Manual for the car.

There is a DTRL Module located in the forward engine compartment, and there are 2 headlight relays located in the battery box at the back of the engine compartment. The relays come after the DTRL module.

My problem is that I don't know which is defective, or even if it's something else.

How would one go about testing said circuit?

Or, is it obvious to you that it's one or the other or something else?

 

[Ceiling Cat]

I am not a mechanic, but I am experienced in electronics. If it is a situation where they sometimes work and sometimes not, sometimes one side but not the other, high beams work both sides, then I would take a look at the electronic module that controls the lights. The other possibility is that if you have a car that turns on the lights automatically, check the sensor that turns on the lights. My sensor is on the dash board at the bottom of the windshield. If it is as simple as a loose connection, then it will have to be traced.

 

[james t kirk]

They are automatic headlights, but that part works just fine.

The problem with the DTRL persists whether the switch is in off, auto, parking lights, or on.

Plus, the DTRL come on as soon as you turn the ignition on, unless the parking brake is set at the time of turning on the ignition.

The problem with buying the module is that you can't return it if it proves not to be the problem.

I am curious to know if there are mechanics on board who would be familiar with the symptoms and can say, "99 times out of 100 it's the module"

 

[Ceiling Cat]

They are automatic headlights, but that part works just fine.

There may be a separate relay for the lights on each side as wall as a resistor circuit that dims the high beams to make them into daytime running lights. The problem may be in the circuit connected to the sensor or it may even be a dual sensor controlling each side independently.

 

[james t kirk]

Here is the wiring diagram for the DTRL circuit....

 

[Darkman5]

Its amazing what you can learn on TERB.

 

[landscaper]

the module has a glitch i it somewhere they are not really repairable os you will have to buy a new or used one. An auto recycler will probably have one if the new one is stupid expensive