1999 Grand Prix GT Coupe Daytime Running Lights wont come on anymore

Anyone run into this and know what the solution/cost might be to fix?

A sensor of some variety? (the sensor which allows the regular
headlights to come on when it gets dark still works though).

Cheers

On Jun 28, 9:16 am, markm75 > wrote:
> Anyone run into this and know what the solution/cost might be to fix?
>
> A sensor of some variety? (the sensor which allows the regular
> headlights to come on when it gets dark still works though).
>
> Cheers

I can't pull up a schematic right now, so bear with a generic answer.
I am pretty certain that your car uses series beams for DRL function
i.e. either the low beams or high beams are rewired in series using
relays or the BCM to send half voltage to each, thus making them
appear less bright in DRL mode. BOTH filaments used in the DRL system
must be working for them to light up when wired in series.

Be certain that both low and both high beams operate in "normal" mode
before wasting any diagnostic time.

If you have amber or otherwise dedicated bulbs for DRL, then ignore
the above and test bulbs, relays, then wiring in that order.

Toyota MDT in MO

On Jun 28, 9:16 am, markm75 > wrote:
> Anyone run into this and know what the solution/cost might be to fix?
>
> A sensor of some variety? (the sensor which allows the regular
> headlights to come on when it gets dark still works though).
>
> Cheers

I forgot to mention that your parking brake input will cancel DRLs by
design. Is the brake warning light on in the dash?

Toyota MDT in MO

On Jun 28, 11:57 am, Comboverfish > wrote:
> On Jun 28, 9:16 am, markm75 > wrote:
>
> > Anyone run into this and know what the solution/cost might be to fix?
>
> > A sensor of some variety? (the sensor which allows the regular
> > headlights to come on when it gets dark still works though).
>
> > Cheers
>
> I forgot to mention that your parking brake input will cancel DRLs by
> design. Is the brake warning light on in the dash?
>
> Toyota MDT in MO

Thanks..

No brake warning light on..

I'm pretty certain my high beams are working correctly too at this
point though.

I thought maybe there was a daytime sensor of some kind (Sorry, I'm
not very car knowledgeable.. more of a PC tech kinda person)..

Comboverfish > wrote:
>
>I can't pull up a schematic right now, so bear with a generic answer.
>I am pretty certain that your car uses series beams for DRL function
>i.e. either the low beams or high beams are rewired in series using
>relays or the BCM to send half voltage to each, thus making them
>appear less bright in DRL mode. BOTH filaments used in the DRL system
>must be working for them to light up when wired in series.

Yes. ALSO there is a DRL relay, which switches the lamps in series
onto a seperate power source with a seperate fuse. That relay is activated
by the DRL module.

Check the DRL fuse under the dash before anything else, then check the
relay.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Jun 28, 11:21 am, markm75 > wrote:
> On Jun 28, 11:57 am, Comboverfish > wrote:
>
> > On Jun 28, 9:16 am, markm75 > wrote:
>
> > > Anyone run into this and know what the solution/cost might be to fix?
>
> > > A sensor of some variety? (the sensor which allows the regular
> > > headlights to come on when it gets dark still works though).
>
> > > Cheers
>
> > I forgot to mention that your parking brake input will cancel DRLs by
> > design. Is the brake warning light on in the dash?
>
> > Toyota MDT in MO
>
> Thanks..
>
> No brake warning light on..
>
> I'm pretty certain my high beams are working correctly too at this
> point though.
>
> I thought maybe there was a daytime sensor of some kind (Sorry, I'm
> not very car knowledgeable.. more of a PC tech kinda person)..

I guess my last big, long-winded post was lost in cyberspace, so I
will recap briefly.

I finally got to see the schematics for your DRL system. Your design
does not series bulbs together as I had guessed earlier. There are no
relays in the system. The low beams are used along with an inline
current reducer for DRL operation. Your likely culprit is the current
limiting device known as the "DRL Diode". An easy test to prove this
part out is as follows:

* Get your system into DRL mode (parking brake off, start engine,
parked in bright sunlight, headlight switch in "OFF" position --
sometimes called "AUTO" on DRL systems).

* Locate the DRL Diode. My component locator shows it to be a
smallish square part that is completely covered in cooling fins. It
has a two wire connector. It is located under/behind the dash on the
far left side. It appears to be just to the left of a trio of relays
arranged on top of one another.

* Assuming the DRLs are currently nonfunctional (no light at all from
headlights) unplug the DRL Diode connector and jumper its two wires
together. If the low beams light up at full intensity, then your
problem is the DRL Diode.

Do this check before any more troubleshooting, as it is a very likely
cause of your symptoms.

Toyota MDT in MO

On Jun 28, 9:16 am, markm75 > wrote:
> Anyone run into this and know what the solution/cost might be to fix?
>
> A sensor of some variety? (the sensor which allows the regular
> headlights to come on when it gets dark still works though).
>
> Cheers

We'll assume that the DRL diode assembly was the culprit. Using "we",
I can single-handedly make an ass out of everyone with just one
statement.

Case automatically closed
Reason: time expired

Toyota MDT in MO