Intermittent errors with Blind Spot Monitor

[RedlandRanger]

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

I wasn't really testing the brake light - I was just making sure the puddle lamps were on - so if they were, the bed lights should have come on. Since I wasn't sure which wire powered the brake light vs the bed lights I just tried them both.

I think I understand what you are saying - you are thinking there is an issue in the ground somewhere between the C3049 connector and the connector to the CHMSL, right? Just thinking out loud, but couldn't I pin in a ground to the CHMSL connector to a good body ground and in theory it should work? (the bed lights, not the brake light) - or I might need to clear the DTC before they will come on? I can jumper the ground and then clear the DTCs and see what happens.

The only reason I did the ground from the battery was trying to eliminate any possible bad grounds - if I went straight to the battery, my thinking was that it HAS to be a good ground so that eliminates me choosing a poor ground spot.

I will experiment some more but it will most likely be a bit (next week maybe unless I squeeze in some time). I've got things the next few days and then we are headed out of town for a few days.

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[RangerBill]

I will experiment some more but it will most likely be a bit (next week maybe unless I squeeze in some time). I've got things the next few days and then we are headed out of town for a few days.

"I think I understand what you are saying - you are thinking there is an issue in the ground somewhere between the C3049 connector and the connector to the CHMSL, right?" Yes, it's possible.

"Just thinking out loud, but couldn't I pin in a ground to the CHMSL connector to a good body ground and in theory it should work? (the bed lights, not the brake light) - or I might need to clear the DTC before they will come on? I can jumper the ground and then clear the DTCs and see what happens." Yes. try that.

 

[airline tech]

So to confirm - you are disconnecting the connector at the light assembly and have the door opened - puddle lights powered and have also tried the cargo light switch , we need to know (eliminate) the light assembly as internally shorted - with it disconnected do you see power at the connector - or are you checking at the circuit board itself

 

[RedlandRanger]

So to confirm - you are disconnecting the connector at the light assembly and have the door opened - puddle lights powered and have also tried the cargo light switch , we need to know (eliminate) the light assembly as internally shorted - with it disconnected do you see power at the connector - or are you checking at the circuit board itself

That is a good call out. I don't think I've tested for power with it disconnected. When I get to this again, I will make sure it is disconnected and test for power at the connector. More to come.

Thank you again for all the suggestions - I keep thinking I've reached my limit and you keep offering ideas - I hope some smoking gun comes up soon so I can fix the issue myself.

 

[RedlandRanger]

I was able to make some time today to do some more experimenting and here is what I found:

• I disconnected the CHMSL and then cleared the DTC for it. I then checked for 12v at the connector - I am not getting 12v there and still no ground.
• With the CHMSL disconnected, I applied a ground to the ground terminal and then touched 12v to each terminal - the light works - both the bed lights and the brake light lit up when applying power to the appropriate terminal. Looking at it from behind, the left terminal (black wire) is the ground, the middle terminal (white wire) is the bed lights and the right terminal (orange wire) is the brake light.
• Just in case I was doing something stupid, I made sure the puddle lights were on and also plugged in the CHMSL and then ran a ground to the ground terminal on the connector - if I did the prior test correctly this should not have worked since we didn't have 12v and as expected, it did not work. So we really don't have 12v at the light.

A couple of thoughts/questions:

• I know there was a mouse underneath the rear seat- there is evidence of chewing in there - is there anything under the rear seat that might be causing this? Does the wire for this light run under the back seat?
• I still have the DTC for the air intake damper position sensor - could that somehow be related to this issue?

 

[RangerBill]

I was able to make some time today to do some more experimenting and here is what I found:

• I disconnected the CHMSL and then cleared the DTC for it. I then checked for 12v at the connector - I am not getting 12v there and still no ground.
• With the CHMSL disconnected, I applied a ground to the ground terminal and then touched 12v to each terminal - the light works - both the bed lights and the brake light lit up when applying power to the appropriate terminal. Looking at it from behind, the left terminal (black wire) is the ground, the middle terminal (white wire) is the bed lights and the right terminal (orange wire) is the brake light.
• Just in case I was doing something stupid, I made sure the puddle lights were on and also plugged in the CHMSL and then ran a ground to the ground terminal on the connector - if I did the prior test correctly this should not have worked since we didn't have 12v and as expected, it did not work. So we really don't have 12v at the light.

A couple of thoughts/questions:

• I know there was a mouse underneath the rear seat- there is evidence of chewing in there - is there anything under the rear seat that might be causing this? Does the wire for this light run under the back seat?
• I still have the DTC for the air intake damper position sensor - could that somehow be related to this issue?

The cable to the stop/cargo lamp runs across the top of the rear window towards the driver side C pillar, down the pillar and across the back of the cab (I believe under the rear seat) to the passenger side of the vehicle. It then runs towards the passenger kick panel under the right side door sills to connector C3049, and out to the engine compartment. The shop manual cable runs are difficult to use, but that is what appears to be the ground wire path.

Did you repair the wires under the rear seat?

 

[RangerBill]

I was able to make some time today to do some more experimenting and here is what I found:

• I disconnected the CHMSL and then cleared the DTC for it. I then checked for 12v at the connector - I am not getting 12v there and still no ground.
• With the CHMSL disconnected, I applied a ground to the ground terminal and then touched 12v to each terminal - the light works - both the bed lights and the brake light lit up when applying power to the appropriate terminal. Looking at it from behind, the left terminal (black wire) is the ground, the middle terminal (white wire) is the bed lights and the right terminal (orange wire) is the brake light.
• Just in case I was doing something stupid, I made sure the puddle lights were on and also plugged in the CHMSL and then ran a ground to the ground terminal on the connector - if I did the prior test correctly this should not have worked since we didn't have 12v and as expected, it did not work. So we really don't have 12v at the light.

A couple of thoughts/questions:

• I know there was a mouse underneath the rear seat- there is evidence of chewing in there - is there anything under the rear seat that might be causing this? Does the wire for this light run under the back seat?
• I still have the DTC for the air intake damper position sensor - could that somehow be related to this issue?

I thought that you said earlier that you had 12 volts to the cargo lamps when the puddle lamps were on, but no ground connection. Is that the case?

 

[RedlandRanger]

UPDATE: FOUND IT!!!

I thought I'd do some cleaning up and look around the rear seat where I knew the mouse was, and on the drivers side there is a wiring bundle that goes thru the sill - there are at least two wires that are severed and 4-6 more that have had the insulation chewed off them. I'm very sure this is the issue - now I just have to figure out how to get the plastic trim off the rear side of the door so I can get a better look at the loom.

 

[RedlandRanger]

I thought that you said earlier that you had 12 volts to the cargo lamps when the puddle lamps were on, but no ground connection. Is that the case?

I'm pretty sure I probably screwed up one of the tests - sorry for the confusion - see my prior post for what I'm sure is the culprit.

 

[RangerBill]

UPDATE: FOUND IT!!!

I thought I'd do some cleaning up and look around the rear seat where I knew the mouse was, and on the drivers side there is a wiring bundle that goes thru the sill - there are at least two wires that are severed and 4-6 more that have had the insulation chewed off them. I'm very sure this is the issue - now I just have to figure out how to get the plastic trim off the rear side of the door so I can get a better look at the loom.

That is likely the problem.

 

[RedlandRanger]

That is likely the problem.

Just to do a quick confirmation, I connected the 3 broken wires together with jumpers, being careful not to touch them - once I did that, the bed lights and 3rd brake light came on when applied. This is definitely the culprit. I wonder if it will resolve the other DTC once I fix these wires?

For the fix - there are 4 or 5 wires that had insulation chewed but don't look damaged other than that. I was thinking about either electrical tape or using some liquid electrical tape on those. For the other 3 wires I was going to solder with heatshrink on the connections. I'd love to hear thoughts on those fixes.

Thank you again for all the ideas and support. After this, I'm going to get some of those scented bags on Amazon so this doesn't happen again

 

[RangerBill]

Just to do a quick confirmation, I connected the 3 broken wires together with jumpers, being careful not to touch them - once I did that, the bed lights and 3rd brake light came on when applied. This is definitely the culprit. I wonder if it will resolve the other DTC once I fix these wires?

For the fix - there are 4 or 5 wires that had insulation chewed but don't look damaged other than that. I was thinking about either electrical tape or using some liquid electrical tape on those. For the other 3 wires I was going to solder with heatshrink on the connections. I'd love to hear thoughts on those fixes.

Thank you again for all the ideas and support. After this, I'm going to get some of those scented bags on Amazon so this doesn't happen again

I would use shrink tubing over the soldered repairs and then regular electrical tape over the repaired area. I would wrap electrical tape over the bare wires individually. Your repairs that you outlined should be good.

Can you restate the other DTC number?

 

[RedlandRanger]

I would use shrink tubing over the soldered repairs and then regular electrical tape over the repaired area. Your repairs that you outlined should be good.

Can you restate the other DTC number?

B11F0:15-08 - Air Intake Damper Position Sensor

 

[RangerBill]

B11F0:15-08 - Air Intake Damper Position Sensor

Could be open or shorted wiring to the damper motor position sensor or a bad damper motor.

B11F0:15
Air Intake Damper Position Sensor: Circuit Short To Battery Or Open

Module senses a short to voltage or an open on air inlet door actuator circuits when motor movement is commanded.

 

[RangerBill]

B11F0:15-08 - Air Intake Damper Position Sensor

You have apparently had this code for quite a while. See this:
https://www.ranger5g.com/forum/threads/resolved-anyone-ever-seen-this.31087/page-2#post-703603

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