2012 W900 left brake light

[Truckdriven]

I have 2012 KW w900 that has no left turn/brake light. Tail works fine and all other lights on the truck, Has a fault code 237213. I checked wiring back to chassis node and all good, Used jumper to put 12 volt to wire terminal at chassis node plug and light comes on fine, checked voltage output at chassis node terminal and got 5.1 volts weather wire is plugged in not, when I turn the brake lights on through ESA simulator or with the brake pedal voltage will drop slightly to 4.8 volt. Checked all Chassis node power fuses and all good. Is my chassis node bad and needs replaced?

[Rawze]

Just a guess...

That node will act up if it gets poor power connections to it...

It is very common to get corrosion in the wiring harness between the outside fuse panel on the drivers side and the chassis node (under the cab)... before it gets to the node.

[Truckdriven]

(10-29-2022 )Rawze Wrote:  Just a guess...

That node will act up if it gets poor power connections to it...

It is very common to get corrosion in the wiring harness between the outside fuse panel on the drivers side and the chassis node (under the cab)... before it gets to the node.

Wouldn't that cause a low power supply fault? I'll check the power supply anyway to verify it

[Mikanic]

You have 2 power pins at connector A (black), 4 power pins at connector B (white) and 2 power pins at connector C (blue). I dont remember the exact pins. You should get a fault from chassis node if your missing power but to know which power circuit you would have to check faults with ESA.
I hope you started your diagnosis by checking the fuses under the hood.

[Truckdriven]

(10-31-2022 )Mikanic Wrote:  You have 2 power pins at connector A (black), 4 power pins at connector B (white) and 2 power pins at connector C (blue). I dont remember the exact pins. You should get a fault from chassis node if your missing power but to know which power circuit you would have to check faults with ESA.
I hope you started your diagnosis by checking the fuses under the hood.

Yes I checked the fuses under the hood and actually back probed each wire after the fuse to ensure the fuses were making proper contact. I have the pinouts of the plugs so I will be able to find the power wires at the node but hadn't studied it enough to know exactly how many wires are in each plug so thanks for that. It will go a few days till my driver gets back to the shop before I can test it farther.

[Rawze]

a similar thread involving that wiring between the outside fuse panel and the node controller...
http://rawze.com/forums/showthread.php?t...2#pid63072

it is a common problem, that wiring harness that goes back that direction.

[Truckdriven]

Wow Rawze nailed it on this one! I finally got the truck back to the shop today and started testing all the chassis node inputs according to the pinout sheet while the light was turned on and found a wire with approximately 2 volts. Also thanks to mikanic for clarifying how many inputs there are. Then came the fun part of finding the bad spot! As much as I do not like to probe through wire insulation that's what I ended up doing about a foot in front of the crossmember that has the chassis node mounted behind and voltage was good so I opened up the harness and soon found a hole corroded in the wire. I will attach a pic. Cut the bad spot out, put adhesive lined heat shrink over my probe hole, soldered the wire back together and all works correctly. I would have thought I would have a low input voltage fault but only had a low output code, so obviously when these nodes act up ALL input voltage wires need to be checked. My gut was telling me the node needs replaced since there was no input fault but as always the proper testing saved a lot of wasted money! Again thanks to all for your advice!

[Rawze]

Thanks for the follow up.. it will likely help others in the future with similar issues.