1998 S70 Bulb Warning Light Issues

ferocity02 · Post by **ferocity02** » 23 May 2016, 16:12

1998 S70 GLT with 187k miles, I've owned it for 4 years now. Ever since I bought it the bulb warning light would occasionally flash when I turn on/off headlights, hit the brakes, activate turn signal, etc. The warning light never stayed lit, it only flash very briefly. But it has gotten slowly worse over time, flashing more often and staying lit for longer, although still only flashing on/off.

About 3 years ago I installed HID headlights and this did not affect the bulb warning light in any way. It was behaving like this before and after the HID install.

Now today when I turn on the headlights the bulb warning light comes on and stays on. All lights appear to be working fine except for one rear fog light bulb. This bulb has been burnt out for years and since I never use the rear fog lights I've never bothered to change it. Because it's been burnt out this whole time I don't think it would be the cause of the warning light now being on all the time when the headlights are on.

Thoughts?

Post by **bmdubya1198** » 23 May 2016, 16:38

I would replace it, whether you use it or not. These bulb warning systems like to flash for everything.

ferocity02 · Post by **ferocity02** » 23 May 2016, 19:06

False alarm regarding the bulb failure light on continuously when headlights are on. One of the front running/parking lights is out.

However, the issue still remains where the light flashes momentarily when turning the headlights on/off, hitting the brakes, activating the turn signals, etc.

Post by **bmdubya1198** » 23 May 2016, 19:51

That's strange. Maybe a relay or the light controller in the back?

Post by **BEJinFbk** » 23 May 2016, 20:11

bmdubya1198 wrote:I would replace it, whether you use it or not. These bulb warning systems like to flash for everything.

Well, the OM sez these anyway:

one of the low beam headlights
one of the tail lights
one of the brake lights when the brake pedal is depressed.
Check the fuse and bulb. See sections "Replacing bulbs" and "fuses".
Should the warning light come on after a defective outside bulb has been replaced, the corresponding bulb on the other side of the car should also be replaced.

Post by **BEJinFbk** » 23 May 2016, 20:13

bmdubya1198 wrote:I would replace it, whether you use it or not. These bulb warning systems like to flash for everything.

Well, the OM sez these anyway:

one of the low beam headlights
one of the tail lights
one of the brake lights when the brake pedal is depressed.
Check the fuse and bulb. See sections "Replacing bulbs" and "fuses".
Should the warning light come on after a defective outside bulb has been replaced, the corresponding bulb on the other side of the car should also be replaced.

If it flashes for ALL those lamps, maybe the module's ground?

Post by **scot850** » 23 May 2016, 23:09

Typically the warning light only comes on when that circuit is operating, so if it is coming on say when you press the brake peddle then one of the bulbs in the circuit is failing or failed.

I'd check that none of the bulbs are loose in the holders or have rust or corrosion building up in them. Clean all the wiring contacts using electrical cleaner.

One light often that is overlooked it the rear licence plate lights. These units are bad for corroding badly and then can cause shorts.

Lastly, check the wiring harness where it is attached to the LHS trunk hinge. Over time these fray and cause shorts.

Neil.

Post by **BEJinFbk** » 24 May 2016, 00:32

If the PO is seeing a blink of the indicator every time he's uses
any of the lamps associated with the Lamp Out system, I'd start
questioning the system, not the lamps. Funky old trailer wiring,
an aftermarket alarm gone bad or maybe even a charging system
issue ( Step 1 - Check The Power Supply! ). Who Knows?

The weird thing is, he see's it with lamps NOT associated with it.

There are two modules that tie back to the dash indicator:
Both low beams are monitored by the high/low beam module
up in the main fuse box - It's the double relay marked 104/108.

The tail light lamps and the brake lamps are run through and
monitored by the little box in the rear left of the trunk/hatch.

The front markers and the license plate lamps aren't watched.
And the Back Up lights are also direct and unmonitored.

Turn signals aren't part of the system, either. But! We still have
some bi-metal based reptilian hindbrain left in these old cars.
They have that cool, "built-in" feature that makes'em blink
faster if one goes out! All at Absolutely No Extra Charge...

The more I think about it - Has this car ever towed anything?