Where is the ebcm in a 2000 gmc yukon

Is the EBCM energizing the BAS relay to turn on the brake lights ?
The brake pedal position sensor receives both a 5-volt reference voltage and a low reference signal from the electronic brake control module (EBCM). When the brake pedal is pressed, a variable signal is applied from the brake pedal position sensor to the EBCM through the brake sensor signal circuit. The fuse block left rear supplies battery positive voltage to the bass relay switch through the BASS fuse. One side of the bass relay coil is permanently grounded at G402. The EBCM supplies voltage to the bass relay coil upon receiving the signal from the brake pedal position sensor. The switch contacts of the bass relay close and battery positive voltage is applied through the bass relay switch to the center high mounted stop lamp (CHMSL), and to the turn signal/hazard flasher module through the stop lamp switch signal circuit. The ground for the CHMSL is applied from G402. The turn signal/hazard flasher module then supplies voltage to the left and right stop lamps in the tail lamp assemblies that have ground at G401 and G402. For export vehicles the stop lamps receive battery positive voltage directly from the bass relay.

Did you have a qualified repair shop check for DTC'S - diagnostic trouble codes ?
DTC B3903 Stop Lamp Relay Circuit
The electronic brake control module (EBCM) supplies voltage to the BASS relay coil side voltage supply circuit when the stop lamps are active. The coil side control circuit of the BASS relay is permanently grounded at G402.

DTC C0278 Brake Pedal Position Sensor Not Calibrated
The brake pedal position sensor (BPP) is a potentiometer. The electronic brake control module (EBCM) supplies a 5-volt reference circuit and low reference circuit to the BPP sensor. The BPP sensor signal circuit is a direct input to the EBCM. The EBCM determines the BPP based on the voltage from the BPP sensor. The EBCM converts the BPP sensor feed back voltage to a digital signal and puts it on the class 2 communication bus.

DTC C0282 Brake Pedal Position Sensor Circuit Range/Performance
DTC C0283 Brake Pedal Position Sensor Circuit Low
DTC C0284 Brake Pedal Position Sensor Circuit High
DTC C0880 Device Voltage Reference Output 2 Circuit

Without knowing if any of these DTC'S are stored do not know what diagnostic direction to point you in .

The ABS EBCM anti-lock brake module is failing causing problems with the ABS pump running constantly, also will drain your battery.

1. Remove the ABS fuse to prevent ABS motor burn out.
2. You can still drive your vehicle with the module removed.
3. We recommend covering the exposed surface of the hydraulic control unit with aluminum foil to keep out water and dirt.

Common Failures:

• ABS Pump Always Running
• Codes: C0265, C0267, C0268
• Pump Motor Circuit trouble code
• Power Relay trouble code
• Valve Relay Trouble code
• Dump Valves (solenoids) trouble codes
• No Communication
• Intermediate power loss

http://www.myairbags.com/dtc-code-c0265-abs-ebcm-light/

You won't find this information in a Haynes manual ! I know , I work for a GMC dealership , along with Chevy and Cadillac ! this information I'm adding is right out of GMC service information .
Diagnostic Instructions
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Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

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Review Strategy Based Diagnosis for an overview of the diagnostic approach.

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Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors
DTC C0561 71: System Disabled Information Stored Invalid Serial Data Received

DTC C0561 72: System Disabled Information Stored Alive Counter Incorrect

DTC C0561 74: System Disabled Information Value of Signal Protection Calculation Incorrect

Circuit/System Description
The electronic brake control module (EBCM) receives serial data messages from the body control module (BCM), engine control module (ECM), instrument panel cluster (IPC), and the transmission control module (TCM) which are needed to perform antilock brake system (ABS), vehicle stability enhancement system (VSES), or traction control system (TCS) functions.
Conditions for Running the DTC
Ignition voltage is greater than 10 volts.
Conditions for Setting the DTC
The EBCM receives an invalid serial data message from another module.
Action Taken When the DTC Sets
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The EBCM disables the traction control system (TCS)/ vehicle stability enhancement system (VSES).

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A DIC message and/or a warning indicator may be displayed.

Conditions for Clearing the DTC
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The condition for the DTC is no longer present.

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The EBCM clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids
This DTC indicates that there are no problems in the EBCM. The BCM, ECM, IPC and the TCM should be checked for a possible fault.
Reference Information
Schematic Reference Antilock Brake System Schematics
Connector End View Reference Component Connector End Views
Description and Operation ABS Description and Operation
Electrical Information Reference ?€¢
Circuit Testing

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Connector Repairs

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Testing for Intermittent Conditions and Poor Connections

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Wiring Repairs
Scan Tool Reference Control Module References for scan tool information
Circuit/System Verification

1. With a scan tool, view the Invalid Signal Data Display.
2. If no invalid signal are present, view Signal Fault Data in the Enhanced DTC Data.
3. Refer to appropriate module for diagnosing the invalid message data.
4. Do not replace the EBCM due to this DTC fault.

You would need a factory scan tool or equivalent too diagnose this ,not a code reader . So do your self a favor an take to a dealership. I've been doing this for thirty years .

EBCM relay is the actual fault code cause. EBCM stands for Electronic Brake Control Module. ECBM stands for Electronic Brake Control Module. It is the big part that the brake lines go into and back out of from the MasterCyl and to the Brakes. It is also the ABS motor all in one. The relay is under the hood at the Fuse/Relay center just inbetween the EBCM/ABS and AirIntake. Relays are big and square. The underside of the Fuse/Relay center cover has the ID and placement embossed into it of everything in the F/R center. Be sure to check the fuses first. The relay needs power to operate and the EBCM or ABS or Brake fuse will be the one for it. Good luck!

The EBCM (Electronic Brake Control Module) is mounted to the BPMV (Brake Pressure Modulator Valve) located at the left front (lower) engine compartment.

EBCM Removal & Installation Procedure

1. Remove the Brake Pressure Modulator Valve (BPMV). Refer to the Hydraulic Control Unit (BPMV) procedure in this section.
   
2. Remove the 4 T-25 Torx® bolts (1) from the EBCM (2). (click image for zoom)
   
   
   Fig. Bolts (1), EBCM (2), bracket (3), bolts (4) and BPMV (5) (click image for zoom)
   
   
3. Disconnect the 2-way ABS pump motor connector.
   WARNING Do not use a tool to pry the EBCM or the BPMV. Excessive force will damage the EBCM.
   
4. Remove the EBCM (2) from the BPMV (5). Removal may require a light amount of force.
   1. Do not reuse the EBCM mounting bolts. Always install new bolts.
5. Clean the EBCM to BPMV mounting surfaces with a clean cloth.

To install:

WARNING Do not use RTV or any other type of sealant on the EBCM gasket or mating surfaces.

1. Install EBCM (2) onto BPMV (5).
   
2. Install the 4 EBCM bolts (1).
   1. Tighten the 4 bolts to 39 inch lbs. (5 Nm) in an X-pattern.
3. Connect the 2-way ABS pump motor connector to the EBCM.
   
4. Revise the tire calibration using the Scan Tool Tire Size Calibration function.
   
5. Use the scan tool to check and clear DTC memory.

Hope this helps.

Motor relay circuit this is for the ABS, you will need ot restore the third eye brake light and check fuse in the engine junction fuse box, (cigarette lighter fuse) make sure it didnt open

EBCM IS UNDERNEATH THE TRUCK CAB IT MOUNTED LEFT FRAME RAIL THE EHCU - BPMV - EBCM ALL THREE CONTROL DEVICES BUILT INTO ONE UNIT.

You mean ecm b fuse, it is in the engine compartment fuse box , look on the left fender firewall , black box labeled fuses and relays... flip lid over it is labled for you to reference...hope this helps...thanks

This is caused by a stuck relay in the EBCM which is under the vehicle below the drivers seat.

No, absolutely not, although the EBCM might possibly be the problem, it is a costly item and 95% of the time is replaced for nothing. Make sure to get the system diagnosed properly, if he can't get a reading from the diagnostic machine, check the abs (EBS) fuse(s), it (they) might be burnt. Then check for fluid level and fluid leaks in the brake system. If these are OK, get the wiring checked to the EBCM for powers, grounds, and data (diagnostics).