Code
P1573
GMC
P — Powertrain
PCM EBTCM Serial Data Circuit
AI status
Completed
Completed
100%
Causes
- Open or damaged wiring in the serial data circuit between PCM and EBTCM
- Corroded, loose, or pushed-out connector(s) at PCM, EBTCM or an intermediate splice
- Short to battery or short to ground on the serial data line
- Failed EBTCM or failed PCM (module internal failure)
- Blown or faulty fuse(s) supplying modules or bus termination components
- Aftermarket electronics or improper service causing bus interference
Symptoms
- MIL (Check Engine) illumination; possible ABS/Traction/Brake warning lamps
- Loss of traction control, stability control, or ABS functionality
- Driveability issues if PCM requires EBTCM data (reduced power, limp mode)
- Scan tool shows EBTCM not present or no serial data stream from EBTCM
- Intermittent or permanent communication-related warnings
- Inability to clear related codes until communication is restored
What to check
- Use a capable scan tool to verify presence of EBTCM on the data bus and check for additional U-codes (lost communication)
- Record live data and attempt to request EBTCM PIDs; note if module appears/disappears
- Check fuses and power/ground circuits for EBTCM and PCM
- Visually inspect EBTCM and PCM connectors, wiring harness routing, and any splices for damage, corrosion, or water intrusion
- Back-probe the serial data line at the EBTCM and PCM connectors with key on and observe for activity
- Perform a wiggle test of the harness while observing scan tool for loss of communication (do safely)
Signal parameters
- Serial data is a digital bus with active data pulses; expected behavior is visible data activity (pulses) when key is ON and modules awake
- Typical voltage range across the bus is between 0 V (active pulses) and near battery voltage (idle/high level); exact idle voltage varies by GM bus type
- Bus should show consistent repeating message traffic from multiple modules when system is healthy
- An open bus will show no activity; a short to ground or battery will clamp the line and prevent normal pulses
- Use a scope to verify pulse amplitude, rise/fall, and bus noise vs. known-good waveform
Diagnostic algorithm
- Connect scan tool, record codes and live data. Confirm P1573 and check for related U-codes indicating lost communication with modules.
- Verify EBTCM and PCM fuses and both modules’ power and ground circuits (voltage supply and good ground). Repair any open/bad circuits.
- Visually inspect connectors and wiring at EBTCM and PCM for corrosion, bent pins, water intrusion, damage, or improper repairs. Repair or replace as needed.
- Back-probe the serial data line at the EBTCM and PCM with key ON. Use a scope (preferred) or DVM to confirm presence of data activity. If no activity, isolate which module stops driving the bus.
- If intermittent, perform a wiggle test of harness with a scan tool connected to reproduce the fault and locate movement-sensitive damage.
- Check continuity of the serial data circuit between PCM and EBTCM with power off to find opens or shorts to ground/power. Repair wiring or connectors as found.
- If bus is shorted to battery or ground, disconnect modules and measure until the short location is isolated; repair damaged wiring or replace faulty connectors/terminals.
- If wiring and connectors check good and bus activity is absent from a module, try swapping or bench-testing the suspect module per service procedure or substitute a known-good module if available.
- After repairs, clear codes, re-scan and verify normal communication and module functions. Reprogram/reflash modules if required by service information.
- If diagnosis requires module replacement, follow programming/configuration steps in service literature and verify the fault does not return.
Likely causes
- Open/short in serial data bus harness near EBTCM or PCM
- Corroded pin or poor ground at EBTCM connector
- EBTCM not powered due to blown fuse or bad supply/ground
- Intermittent communication due to damaged wiring chafing when steering or suspension moves
- Failed EBTCM (module not transmitting)
- PCM not responding to or reading the serial data bus
Fault status
Status
Loss or interruption of serial data communication between the PCM and EBTCM. Circuit fault (open/short/high resistance) or module not responding on the data bus.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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