Service trailer brake system and ABS light on?

Good afternoon.

Do you have a scan tool to monitor the sensor activity while you are moving?

You will need to use your voltmeter to check the activity of the sensors. I attached possibilities below as well as the flow chart.

It looks like it is a sensor. You have one on each wheel. Check them and the harness carefully. Make sure none of the wheel bearings have any play.

Roy

C0035
Descriptor
Probable Causes
Air Gap Between Wheel Speed Sensor (WSS) and Encoder Ring Excessive
Connections or Wiring Causing Intermittent Condition
Electronic Brake Control Module (EBCM)
Electronic Brake Control Module (EBCM) Harness Connector Poor Connection
Electronic Brake Control Module (EBCM)) Ground, Connections or Circuitry Intermittent Condition
Encoder Ring Teeth Damaged
Harness or Connector Water Intrusion
Wheel Speed Sensor (WSS)
Wheel Speed Sensor (WSS) Circuits Open
Wheel Speed Sensor (WSS) Circuits Short to Ground
Wheel Speed Sensor (WSS) Circuits Short to Voltage
Wheel Speed Sensor (WSS) Circuits Shorted Together
Wheel Speed Sensor (WSS) Harness Connector Poor Connections
Wheel Speed Sensor (WSS) Loose or Mounted Incorrectly
Wheel Speed Sensor (WSS) or Encoder Ring Debris
Wheel Speed Sensor Circuits Water Intrusion
Wheel Speed Sensor Mounting Surface Contaminated

flow chart

DTC C0035 or C0040
Circuit Description
As the wheels spin, each wheel speed sensor produces an AC signal. The electronic brake control module (EBCM) uses the frequency of the AC signals to calculate each wheel speed.

Conditions for Running the DTC
The ignition is ON.
The vehicle speed is greater than 13 km/h (8 mph).

Conditions for Setting the DTC
Any of the following occurrences may cause the DTC to set.
The EBCM detects an open or shorted wheel speed sensor circuit for 500 milliseconds.
The EBCM detects the absence of a wheel speed sensor signal for 5 seconds. If more than one absent wheel speed sensor signal is detected, the condition must be present for 120 seconds to set DTC's.
The EBCM detects an erratic wheel speed sensor signal for 200 milliseconds.

Action Taken When the DTC Sets
The EBCM disables the ABS and may disable the dynamic rear proportion (DRP) if more than one wheel speed sensor DTC is set.
The ABS indicator turns ON.
The brake warning indicator may turn ON.
The actions above are maintained during subsequent ignition cycles until the EBCM completes a power up self-test. This test concludes when the vehicle achieves a speed greater than 13 km/h (8 mph) and the wheel speeds are verified by the EBCM.

Conditions for Clearing the DTC
The Conditions for Setting the DTC are no longer present and you use the scan tool Clear DTC's function.

Diagnostic Aids
Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to Testing for Intermittent Conditions and Poor Connections, Connector Repairs, Testing for Electrical Intermittent and to Wiring Repairs. See: Vehicle > Component Tests and General Diagnostics
If the customer's concern is that the ABS indicator is on only during humid conditions such as rain, snow, or vehicle wash, thoroughly inspect the wheel speed sensor circuits for signs of water intrusion. Use the following procedure in order to help isolate the problem area:

1. Spray the suspected area with a 5 percent salt water solution.
2. Operate the vehicle at a speed greater than 13 km/h (8 mph) for at least 30 seconds. Repair or replace the suspect harness if the DTC sets.

Sounds like a plan. Keep me updated.

Roy

The resistance of the sensors should be 800-1100 ohms.

You need to check for ac voltage. They are voltage generators and produce ac voltage.

What happened to the scan tool that will monitor the sensors while driving?

Roy

Hello,

It sounds like something brake or is worn in the parking brake system of the truck. here is a guide and diagrams to help you see whats going on:

https://www.2carpros.com/articles/parking-brake-shoe-replacement

Please run down this guide and report back. Can you please shoot a quick video with your phone so we can see what's going on? that would be great. You can upload it here with your response.

I am sorry, I see you said you did not have a scan tool.

Check the sensors again and recheck ac voltage and ohms.

Roy

Okay, that will tell us which sensor is causing the issue when the light shows.

Roy

Okay, then lets see if it is still showing that side when you get the scan tool. If it does, then the harness needs to be checked to see if there are any fraying or bad wiring.

Roy

You are welcome.

Always glad to help.

It sounds like a short to power that is back feeding when the key is off and turning the lights on. Now, where do we start. Try this. With the key off (and the lights staying on) remove one fuse at a time to see if there is one that shuts the lights. By doing this, we may be able to locate the circuit which is causing the issue. Also, check to make sure there is no damage to the wiring under the hood in the main fuse/relay box. Make sure none of the pins where things push in are damaged, melted, pushed out.

Let me know what you find.