Low Beam Headlights Stopped Working

[MassTransitConnect]

Hi everybody,

The low beams on my 2019 Transit Connect xl (2.0l GDI) died one at a time this week. When I replaced the bulbs, the lights still don't work.

The high beams, the marker lights, and the fog lights all work but not the low beams.

I hooked ForScan up to the van and found the following errors in the Body Control Module:

 

Module: Body Control Module===END DTC C1D00:11===

===DTC B1D01:15===

Code: B1D01 - Right Low Beam

Additional Fault Symptom:

- Circuit Short To Battery Or Open

Module: Body Control Module===END DTC B1D01:15===

===DTC B1D00:15===

Code: B1D00 - Left Low Beam

Additional Fault Symptom:

- Circuit Short To Battery Or Open

 

I checked the physical condition of the headlight plugs and they're fine. I checked the fuses (31, 44, 49) in the engine compartment fuse box. I checked the BCM fuse but it's good too. I used ForScan to reset the DTC and reset the Body Control Module. The fault returned immediately.

Does this situation sound familiar to anyone? Should I cross-post this somewhere else?

I'd appreciate any guidance or troubleshooting tips you can provide.

[Fifty150]

Get a circuit tester. Start looking for the problem.  You will have to physically test the wires.

[MassTransitConnect]

Hey Fifty thanks for the reply

I've got a circuit tester on it's way in the mail, so I've got to wait a couple days to start that.

I'm not sure where to begin because I'm not sure what role the body control module plays in the low beam circuit.

 

The error says "Circuit Short To Battery Or Open" so the BCM detected this state and disabled the low beam circuit?

 

I don't have a solid game plan yet to diagnose this but when I get my new tester, I'll put in the work.

 

 

 

[Fifty150]

18 hours ago, MassTransitConnect said:

 

I don't have a solid game plan yet to diagnose this but when I get my new tester, I'll put in the work.

 

I guess you can start at the lamps.  Pull the lamp, and check the circuit with the tester.  See if you have 12v positive on both.  That will eliminate half of the circuit.  Then you can start checking the ground side.

 

Circuit testers have really gone up in price.  I bought one in the pre-Covid days for about $15.  I guess they can blame Covid for price hikes on everything.

 

 

 

 

[MassTransitConnect]

Yeah things have gotten pricey lately.

 

I'll check the positive then the ground path like you said. The thing is, I think this might be a failed Body Control Module.

The pass. side light went out first then the driver side a day later.... The BCM told me that it sensed a "Circuit Short To Battery Or Open" on both circuits and I can't logically see that actually being in the harness.

What I anticipate seeing with the tester is no voltage on the pos side because the BCM is blocking the circuit. That's going to make testing a little more complicated than the old style with relays, etc.

 

I have ForScan so if there's a function of that software that you recommend I try, I'll do it.

The module was reset twice and the DTC returned both times.

 

My prediction is that the short is in the BCM not the harness.

 

Thanks for replying....have a great new year!?