No taillights No marker light on drivers side

mike_barbato said:

And the fuse is good..BCM?

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Maybe. If you have a scan tool, I'd check for codes. It might have one that signifies a short somewhere.

I'd also examine each bulb (there's 5). Make sure they're all good. Sometimes when a bulb blows, it can short out. The BCM may be protecting itself.

But it boils down to 3 things:

• Fuse - make sure it tests good electrically. It could have a hairline fracture. It may good good, but in fact be bad. If in doubt, swap it. It's cheap.
• The BCM - of last resort. $$$$
• Wiring/connectors - not sure what to advise. It could be a short anywhere, or a open near the BCM.

Note: if ANY of the 5 bulbs involved work, then you're looking at a open in the wiring somewhere. The 5 bulbs are: Left front parking light, left front side light, left rear side light, left brake light/tail light (fender mount), left tail light (trunk mount).

Worse thing about an inoperative light bulb, some cop may shoot you for this.

An ohmmeter is a very handy device to have, can get a decent VOM for under 20 bucks now. Fuse on the lowest range should show zero ohms on the lowest range. Ha, these new fuses are so tiny, practically need a microscope to see that internal link. But a blown fuse means a lot more problems, long ride from the fuse box to way back there, shorts blow a fuse

Rear lighting harness on the Cruze is very short that plugs into the main harness.

Only a single tab on my Cruze's backup lights and got one that was backwards, had to bend the tab in the other direction, insisted on a correct harness, dealer said no, as long as that works, but another potential problem, should be using a double tab.

Then bare brass that can corrode preventing good contact. Those tabs is all that holds the bulb in and if spread, bulb can fall out, or simply not make contact. But usually one or two bulbs, not all of them.

I do voltage checks, hard to find a good ground on these things, and only one guy, so made 20' long reads for my VOM, have a battery clamp on the negative that goes directly to the negative terminal on the battery. Start at the fuse panel and work back.

Hope this helps.

View attachment 177393

This is what the BCM looks like on the Cruze, has seven connectors points on it labeled X1 through X7, on ebay for as cheap as 50 bucks, but may have to pay your dealer a hundred bucks to program this. Don't get this, not a darn thing to do with emissions, should be a free download, but just another way to get robbed. Guys on this board had to lay out a hundred bucks just to get their fog lamps to work. This is a darn right dirty trick, shame on you GM.

View attachment 177577

Not sure which socket is X1, but B+ or 12 volts enters pin 3 of X2, B+ is an old term referring to vacuum tubes, Vcc is used for low voltage solid state. With parking lights on, pin 6 of X4 should show voltage. Doesn't appear to be very easy to measure.

Circuit diagram shows a point contact relay contacts, now this is a good question, is it a point contact relay or a power MOSFET transistor. Only way to find out is to open it and hand trace the lands. Typically a transistor with an overload will short out so the lights will be on all the time. Where one tiny spec of dirt can keep the contacts from making contact.

So at this point, your guess is as good as mine, but for me, worth looking at before buying a new one, also found cold solder joints on those many connector pins, ha, saved me 1,300 bucks on one vehicles ECU. And more than once.

An old saying is the the best connector is no connector, offers some convenience, but sure introduces new problems, Made In China doesn't help either.

Curious as to how you are making out with your dead tail lamps. If it happened to you, can happen to the rest of us. Can be something as simple as those fuse tabs are spread apart, you never want to rock any of these to pull them out, have to come out straight. Talk about cheap, and not only hardware problems but software problems as well, only need one corrupt byte.

Ha, have a total of 18 marker and parking lamps on my motorhome, the shear volume was the major problem, but for getting 12V, only had to pull out the head lamp switch out one notch. Law doesn't help either, one bulb not working is reason to get stopped and even searched, and you have to be very very nice.

Ha, talk about fighting for freedom, don't have to go the middle east, we should be doing this right here. Called this political electronics.

Cruze uses those tab bulbs like this.


They are not any better than the old fashion bayonet type bulbs, that need a brass base and a brass socket to turn them into, but definitely cheaper to manufacture. Instead of brass, and should be plated, use a piece of plastic with what should be a double U-shape tab hot on both sides, Cruze is only using a single tab.

On one of my back up lamps, that single tab was put in on the wrong side from the factory, so that bulb wouldn't work at all, I had to bend those cheap wires to the other side. Told my dealer about this, that harness is rather short for all the lamps, but refused to replace it, as long as bending those tabs to the other side worked.

Also the brass tabs inside that plastic housing can corrode so you don't make good contact, can be cleaned and coated with silicone to help retard corrosion.

Do you think there is a conspiracy between the cops and these socket manufacturers, so cop has a right to stop you in one bulb out? In Wisconsin, also have the right to search your vehicle when stopped. Not sure about other states.


Oh, and if Black and not cooperative, they will shoot you, because of a cheaply made bulb and socket.

Also found it convenient for me to open up that grommet that prong of the tail lamp housing plugs into and coating that with silicone grease.

Darn thing was so tight from the factory, darn near broke the housing trying to pull it out, not a darn reason in the world it has to be that tight. Think a member of this board said he broke his housing. I used a suction cup and a tow truck to pull mine out the first time.

For years been carrying a full complement of replacement bulbs and the tools I need to change them along with fuses all in a plastic bag sitting on top of my spare tire. With an easy to remove tail lamp housing, just a small phillips screwdriver.

For practically all vehicle I have owned for the front amber directional and parking, used a colored lens for this, same clear bulb as the rears. Cruze just had to use an amber bulb for this so had to buy two more. Its little details like this that tend to make me hate bean counters even more.

This way if stopped, a bulb can burn out at anytime, can change it then and there to avoid getting a warning ticket, then having to mail that in once a bulb is replaced.

Those front bumper marker lights are a pain to replace, have to turn the front wheel in, and pop out a bunch of those push pin rivets at the wheel well. Not even sure they are there, just a tiny 2 watt 194 bulb in there, with plenty of side lighting with that head lamp housing clear around the side. Can't even notice if they are on or not.

And it sure doesn't help getting all of this made in China crap.