Intermittent errors with Blind Spot Monitor

[RedlandRanger]

Is the black wire at the light housing connected to ground? Test using an ohmmeter. If it is grounded (close to zero ohms) and you have no 12 volts DC at the cargo light (when turned on) or stop light (when brake pedal is pressed), then you will have to follow the wiring back to the BCM (Body Control Module) and look for broken wiring or connectors.

All 3 wires going to the light housing are in plastic - I can't see where they go really. I will probably need to remove at least part of the headliner. I will see if I can spend some time on that tomorrow.

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[airline tech]

Since you have a LED Assembly - the assembly itself be shorted or you have lost ground, the BCM may have tripped FET Protection for the CHMSL, the Cargo Lights side did not trip as you have Puddle Lights - (Shared Circuit) with the Cargo Lights

If you look at C275, this is a splice via the connector that splits the circuit for Puddle & Cargo, note the Puddles have there own ground.
The CHMSL & Cargo - share the same ground - I think that you have either lost this ground or the assembly is shorted and the BCM has tripped FET protection, the puddle lights continue to work as they have a ground path.

The CHMSL is a direct run from the BCM to the light assembly

For Ref: C275 and C3049 -locations

Check C275 - for the Cargo/ Puddle Split
and
Check C3049 - for corrosion as this holds the ground for the CHMSL & Cargo Lights

The Connector for the light assembly is just under the headliner

 

[RedlandRanger]

Since you have a LED Assembly - the assembly itself be shorted or you have lost ground, the BCM may have tripped FET Protection for the CHMSL, the Cargo Lights side did not trip as you have Puddle Lights - (Shared Circuit) with the Cargo Lights

If you look at C275, this is a splice via the connector that splits the circuit for Puddle & Cargo, note the Puddles have there own ground.
The CHMSL & Cargo - share the same ground - I think that you have either lost this ground or the assembly is shorted and the BCM has tripped FET protection, the puddle lights continue to work as they have a ground path.

The CHMSL is a direct run from the BCM to the light assembly

For Ref: C275 and C3049 -locations

Check C275 - for the Cargo/ Puddle Split
and
Check C3049 - for corrosion as this holds the ground for the CHMSL & Cargo Lights

The Connector for the light assembly is just under the headliner

Do you know - is there an easy way to get to that connector under the headliner without removing the whole thing? It looks pretty involved to pull the headliner down.

I will take a look at those two connectors in the kick panels to see what I find.

 

[RedlandRanger]

I ended up finding a way to pull down the edge of the headliner and was able to inspect the connector to the CHMSL - it looked totally normal - no corrosion, dirt or evidence of wire damage.

I also inspected the C275 and C3049 connectors in the two footwells. Again, both looked completely normal - clean, no corrosion or evidence of any damaged wires.

I may be approaching the limits of what I can do but if you have additional suggestions I will try and see what I can do. Thank you again for your suggestions.

One thought (and I didn't check these yet) - this couldn't be something really stupid like a blown fuse could it? I looked at the fuse diagrams and nothing seemed to point to one specifically for this unit.

 

[RangerBill]

I ended up finding a way to pull down the edge of the headliner and was able to inspect the connector to the CHMSL - it looked totally normal - no corrosion, dirt or evidence of wire damage.

I also inspected the C275 and C3049 connectors in the two footwells. Again, both looked completely normal - clean, no corrosion or evidence of any damaged wires.

I may be approaching the limits of what I can do but if you have additional suggestions I will try and see what I can do. Thank you again for your suggestions.

One thought (and I didn't check these yet) - this couldn't be something really stupid like a blown fuse could it? I looked at the fuse diagrams and nothing seemed to point to one specifically for this unit.

A blown fuse would cause the puddle lights to also not work as they are fed from the same FET switch in the BCM. So, you have confirmed that you are not getting 12 volts to the lights and that there is a good ground to the light?

 

[RedlandRanger]

A blown fuse would cause the puddle lights to also not work as they are fed from the same FET switch in the BCM. So, you have confirmed that you are not getting 12 volts to the lights and that there is a good ground to the light?

OK - I figured it was a stupid idea but I thought I'd just throw it out there.

As I said, I'm rapidly approaching my limits, but I think I am NOT getting a ground to the CMHSL light. The way I tested it was to run a wire from the positive of the battery to my test light and then put a pin in the black incoming wire. I believe if I had a ground there I should have gotten a light but I did not. Touching the test light to the negative on the battery (obviously a good ground) and the light comes on. So I think you are both correct that the ground is being lost somewhere.

I then reversed the setup and connected my test light to the ground on the battery and put a pin in both the orange and white wires on the CHMSL connector (there is only a black, orange and white wire - the diagram above looks different or I'm reading it wrong). I got no light on either of the orange or white wires. It looks like black is the ground and orange and/or white should have power when the puddle lights are on (which they were).

 

[RangerBill]

OK - I figured it was a stupid idea but I thought I'd just throw it out there.

As I said, I'm rapidly approaching my limits, but I think I am NOT getting a ground to the CMHSL light. The way I tested it was to run a wire from the positive of the battery to my test light and then put a pin in the black incoming wire. I believe if I had a ground there I should have gotten a light but I did not. Touching the test light to the negative on the battery (obviously a good ground) and the light comes on. So I think you are both correct that the ground is being lost somewhere.

I then reversed the setup and connected my test light to the ground on the battery and put a pin in both the orange and white wires on the CHMSL connector (there is only a black, orange and white wire - the diagram above looks different or I'm reading it wrong). I got no light on either of the orange or white wires. It looks like black is the ground and orange and/or white should have power when the puddle lights are on (which they were).

The ground G123 is located in the engine compartment on passenger side front as shown by the red line in this shot:

The connector in series with the ground wire is located in the passenger compartment kick panel area as pictured by the red arrow below:

These areas would be a good place to look for the open ground.

 

[RangerBill]

OK - I figured it was a stupid idea but I thought I'd just throw it out there.

As I said, I'm rapidly approaching my limits, but I think I am NOT getting a ground to the CMHSL light. The way I tested it was to run a wire from the positive of the battery to my test light and then put a pin in the black incoming wire. I believe if I had a ground there I should have gotten a light but I did not. Touching the test light to the negative on the battery (obviously a good ground) and the light comes on. So I think you are both correct that the ground is being lost somewhere.

I then reversed the setup and connected my test light to the ground on the battery and put a pin in both the orange and white wires on the CHMSL connector (there is only a black, orange and white wire - the diagram above looks different or I'm reading it wrong). I got no light on either of the orange or white wires. It looks like black is the ground and orange and/or white should have power when the puddle lights are on (which they were).

Ground splice S145 is located by the red arrow in the picture below in the passenger side engine compartment:

 

[RedlandRanger]

I looked at the connector and wires in the passenger foot well earlier - that all looked fine. I looked at the two ground locations in the engine bay and they both looked fine too. I'm guessing I must have a broken wire somewhere between there and the lights?

 

[RangerBill]

I looked at the connector and wires in the passenger foot well earlier - that all looked fine. I looked at the two ground locations in the engine bay and they both looked fine too. I'm guessing I must have a broken wire somewhere between there and the lights?

If you have an ohmmeter, you can measure at the connectors to ground (chassis). I should be close to zero ohms. That would pinpoint the place where the ground connection is lost. The ground wire is black.

 

[RedlandRanger]

If you have an ohmmeter, you can measure at the connectors to ground (chassis). I should be close to zero ohms. That would pinpoint the place where the ground connection is lost. The ground wire is black.

The two ground points in the engine bay both had close to zero so they appear to be good ground points.

 

[RangerBill]

The two ground points in the engine bay both had close to zero so they appear to be good ground points.

What about the connector behind the passenger side kick panel? Does it measure zero ohms to ground?

 

[RedlandRanger]

What about the connector behind the passenger side kick panel? Does it measure zero ohms to ground?

I tested it and it seemed good as well.

How I tested (tell me if I did it wrong) - I ran a wire from the negative terminal on the battery and hooked that to one side of my multimeter. (I figured that was the best ground I could get) I then touched the other side to the ground point (or pin 2 in the case of the connector in the footwell - the black wire). Once I completed the circuit they all came back at 0 or close to it (0.01). I did the same thing on the CHMSL connector (the black wire) and it was jumping all over the place.

As a test, I then took that wire from the battery and I touched it to the black connector on the CHMSL (thinking it would give it the ground it appears to need) to see if that would get it to turn on. Nothing happened. Not sure if that was a good test or not, but in my mind, it seemed logical.

If I'm understanding this all correctly, it seems to point to a short/open somewhere between that connector in the passenger footwell and the connector up at the CHMSL..

 

[RangerBill]

I tested it and it seemed good as well.

How I tested (tell me if I did it wrong) - I ran a wire from the negative terminal on the battery and hooked that to one side of my multimeter. (I figured that was the best ground I could get) I then touched the other side to the ground point (or pin 2 in the case of the connector in the footwell - the black wire). Once I completed the circuit they all came back at 0 or close to it (0.01). I did the same thing on the CHMSL connector (the black wire) and it was jumping all over the place.

As a test, I then took that wire from the battery and I touched it to the black connector on the CHMSL (thinking it would give it the ground it appears to need) to see if that would get it to turn on. Nothing happened. Not sure if that was a good test or not, but in my mind, it seemed logical.

If I'm understanding this all correctly, it seems to point to a short/open somewhere between that connector in the passenger footwell and the connector up at the CHMSL..

The black wire should have a good close to zero ohm reading to ground, it should not be jumping around. Take your ohmmeter and check for near zero resistance reading between the black wire at the stop lamp assembly and the black contact in the connector C3049 connector pin 2 (at the passenger kick panel). That will ring out the ground wire from that connector to the stop lamp assembly. For either cargo lamps or stop lamp to light, you need 12 volts at each wire to the light and a good ground connection.

If you take a voltmeter and connect the black lead to the black wire on the stop light/cargo lamp connector and the red voltmeter lead to either of the two other wires on the lamp assembly with the puddle lights on and the brake pedal pressed, you should see 12 volts DC on either of the two wires.

 

[airline tech]

So you have to keep in mind that the code for the CHMSL may be a locked code and must be cleared for the BCM to allow power out, plus also since you have not mentioned it, the 3rd brake light will only be powered when brakes are applied, if the ground test is jumping around and not the same result as the cargo light test- then something is affecting that ground- either a bad ground or a short (between power and ground) - I would do the same test , you do not need the wire from battery (neg) just black lead to body ground and red lead to ground wire (ohms) scale - you should get close to (0) on the C3049 connector then between that connector and the light connector- determine which side of the connector has lost ground, or the light connector- jumper the black wire to ground and then go to the c3049 connector and ohm the black wire to body ground - I think this section is where the fault lies

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