[FIXED] Right Front Turn Signal Issue

ok guys I have a good one here working on a 2007 Cadillac DTS 4.6L. The problem is the right turn signal bulb is inop. The wiring from the BCM to the turn signal bulb is good not shorted or open. To confirm this I put power at the BCM connector I believe its Connector 4 Pin 5 (unplugged) and the turn signal bulb comes on. Next I plugged the connector back and check for voltage out put on the connector and pin (back probing) and found non. No brainer right. I installed a new BCM and Programmed it and guess what still no right front turn signal. It seems that the BCM is shutting down the driver for the right front turn signal. The BCM is setting a code B2615 Passenger Compartment Dimming 2 Circuit. What do you guys Think? Thanks

i would do a bi directional control with a scan tool to turn the right front light on. and if it does come on I would look for an input problem. maybe you got a bad new bcm??

can you put up a pinout of the turn signal switch on the forum? id check the turn signal switch input

Check all of your power feeds. Many times there are more than one fuse for the BCM. Second is inputs from the turn stalk switch. I'm guessing that the rear is working so it may be a mute point.

Third a 2 filament bulb may find a ground through the other circuit. So checking your ground is critical.

Posting up a wiring diagram for easy reference:



Good one, indeed! Good move powering the lamps from the connector, love it. Any chance that the female pin inside the connector is spread? Unlikely, I know, but it'd explain your symptoms.

Besides what Chris and Cheryl noted, the only other thing I can think of is that the BCM is watching those lamp circuits closely, and is finding something it doesn't like. It's a power side driver, and it's my experience that power side drivers usually monitor for current flow and circuit integrity.

It may be worth checking the behavior of the LF turn signal, to get an idea of how the BCM operates (I'm thinking of some kind of bias voltage here, like Dodge uses on their trucks). You could also compare the resistances of the LF and RF circuits, see if there's a significant difference. Or, power the signals manually and measure their respective current draws.

EDIT: Another idea, you could try swapping the LF and RF signal pins in the BCM connector? Then, you'd be using the LF driver to run the RF signal. If the RF still won't light, then you can be pretty sure there's something in that circuit that it doesn't like.

I don't know these vehicles but some lighting system modules are sensitive to detect if the bulb is the wrong wattage.

Andy.MacFadyen wrote: I don't know these vehicles but some lighting system modules are sensitive to detect if the bulb is the wrong wattage.

This is what I was thinking. I remember working on a Mercedes with an inop turn signal, owner had installed the wrong bulb. The car figured this out immediately and refused to run the turn signal driver.

Tyler wrote:

Andy.MacFadyen wrote: I don't know these vehicles but some lighting system modules are sensitive to detect if the bulb is the wrong wattage.

This is what I was thinking. I remember working on a Mercedes with an inop turn signal, owner had installed the wrong bulb. The car figured this out immediately and refused to run the turn signal driver.

I'm in the same boat as these guys. Interested to see how this one plays out.

sorry guys for the late reply. Chriscoy had the right idea about the fuses although I did check them in the begging. It ended up being a missing fuse in the rear fuse box that powered the BCM. The owner had just bought this car from a used car lot. I did check the bulb too like Tyler suggested. I also tried swapping the left and right signals, but in the end it was a missing fuse. Rookie mistake. Thanks again

fsteddie98 wrote: sorry guys for the late reply. Chriscoy had the right idea about the fuses although I did check them in the begging. It ended up being a missing fuse in the rear fuse box that powered the BCM. The owner had just bought this car from a used car lot. I did check the bulb too like Tyler suggested. I also tried swapping the left and right signals, but in the end it was a missing fuse. Rookie mistake. Thanks again

Glad to hear it, sir! Points to Chriscoy for hitting this one on the head

No worries about the fuse, man. This is a used car lot vehicle? ANYTHING can happen with those, lol. Box of chocolates and all that.

Just for my own info, I went and found the diagram with (what I suspect) was the missing fuse:



I'm honestly surprised they have separate fuses for these outputs, but there they are! In retrospect, I probably could have dug a little deeper and found this, oh well.

I'm calling this one [FIXED]