Battery light on DRLs off

[fblainen11]

I have an 01 with DRLs. Today I turn the key and it starts right up with no issues, but I notice my battery light is on.
Sitting in traffic I notice on the truck in front of me that I can't see my headlight reflection. I check the headlight stalk and they're off, but I should still see DRLs like I normally can. Turn the lights on and sure enough they come on.

I got home and double checked and verified that DRLs are not working.

Anyone know what's going on and why these two issues have come up together?
Fuse?

 

[Austin_Snider]

Yup fuse is what I would check

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[fblainen11]

Pulled the fuse. It's fine. I cannot locate my multimeter right now. Our house is under construction from flood repairs and things are in a bit of disarray.

I'm thinking my alternator may be going bad. My lights appear dimmer than normal.
Anyone know if an alternator slowly "goes bad". I'm thinking if there's some kind of relay that tells the DRL's to turn on at a certain voltage that the alternator provides it may not be getting what it needs to turn them on.
So if alternator is at 14v, and that's what the relay needs, then that explains the DRLs not working, but the lights working when I turn the stalk on.

Any input?

 

[RedSled]

I would say the battery is going, just a guess though.

 

[19963.4lsr5]

You need to find your volt meter and see if your alt is working. If the DRL's use both high and low beams in series to divide the applied voltage by 2 I can see a relay or relays being part of the circuit. I think the make voltage for those coils (unless it's a special application) is around 8-10vdc. And if your battery voltage was that low I don't think your ECM would turn on.

If Durk doesn't chime in when I get to work this evening I'll look at the wiring for a 2002 and see what's involved in making the DRLs operate.

Look for your meter or go to Walmart and buy a cheep one to get you by.

Also most all DRLs are run through the ebrake circuit. So if the ebrake is on the lights are off. Is your brake light on in the instrument cluster?


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[4Reak Show]

DRL module/relay linked directly to alternator. Looks like the engineers don't want the DRL's on if alternator fails to save electrical power.

The yellow/green wire comes directly off the alternator as you can see.

You need an alternator 99.9% certainty. Good luck

 

[TheDurk]

Did you check the 10A IGN fuse? That supplies both the BATT light and the DRL relay input. So first suspect. After that, check alternator function.

 

[IBallEngineer]

:target:

Pulled the fuse. It's fine. I cannot locate my multimeter right now. Our house is under construction from flood repairs and things are in a bit of disarray.

I'm thinking my alternator may be going bad. My lights appear dimmer than normal.
Anyone know if an alternator slowly "goes bad". I'm thinking if there's some kind of relay that tells the DRL's to turn on at a certain voltage that the alternator provides it may not be getting what it needs to turn them on.
So if alternator is at 14v, and that's what the relay needs, then that explains the DRLs not working, but the lights working when I turn the stalk on.

Any input?

Alternators are more important than DRL's. You can't troubleshoot electrical circuits without a DVOM. What fuse did you pull and "check"?

Two fuses for charging 10A gauge and 10A ign. The fact that the alternator light is on, indicates the 10A ign fuse is good, this fuse powers the light, and when the alternator is "excited" by the ignition circuit and begins generating, voltage is applied on the ground side of the lamp, thereby turning off the light. This is the same circuit that sends alternator voltage to the DRL main relay. This is done so the DRL don't come on until the engine is running, not to conserve power if the alternator fails.

Bottom line here is if the Alternator is not charging, the DRL's will not work. Before anything can be diagnosed, you MUST know if you the alternator is functioning correctly.

The DRL main relay also uses power from the 10A gauge fuse, in addition to the 15A dome fuse. This is true on 2000 through 2002, although there are subtle differences between 00 and 02, I don't know how that applies to 01.

Since I am busy with important projects like, having lunch, and browsing CL for Bass amps and Land Cruiser parts, I'll have send a shout out for El Durko.
[MENTION=10169]TheDurk[/MENTION]

 

[fblainen11]

I pulled the DRL fuse.
My gut instinct was right. It was the alternator.

Went off shore fishing and when I came back no go on starting.
Jumped it to try to make it home, as soon as I gave it throttle it died.

We (my two brothers and I) pulled the battery and alternator.
Tested both, battery was dead but okay, alternator was bad.

Replaced alternator and had parts store charged the battery
Voila. Fixed.

 

[4Reak Show]

Good stuff man glad to hear it.
Thanks for the update