Code
P1573
CADILLAC
P — Powertrain
PCM EBTCM Serial Data Circuit
Views:
UK: 24
EN: 38
RU: 31
AI status
Completed
Completed
100%
Causes
- Open or short in serial data wiring between PCM and EBTCM
- Corroded, loose, or damaged connector at PCM or EBTCM
- Failed EBTCM or failed PCM/module hardware
- Blown fuse or poor power/ground to one of the modules
- Aftermarket accessory or recent repair disturbed wiring or network
- Intermittent wiring damage from chafing, water intrusion, or rodent damage
Symptoms
- ABS/Traction Control warning lamp illuminated
- Check Engine Light or multiple communication-related DTCs stored
- Loss of ABS/traction functions or degraded braking/traction availability message
- One or more modules not responding to scan tool or missing from network list
- Intermittent faults that appear/disappear with vibration, temperature, or connector movement
What to check
- Use a capable scan tool and read all stored U/P codes and module presence on the vehicle network
- Verify battery voltage and charging system are within specification before diagnosing network issues
- Confirm EBTCM and PCM appear on the bus (module list) and note any other communication codes
- Visually inspect PCM and EBTCM connectors and harnesses for corrosion, bent pins, water, or damage
- Inspect related fuses and power/ground circuits for both modules
- Perform wiggle test of harnesses while monitoring network messages for intermittent changes
Signal parameters
- Serial data message presence: continuous stream of messages from EBTCM when vehicle is on (verify with scan tool or scope)
- Idle and active waveform integrity: no missing frames, long gaps, or distorted pulses (compare to GM service data)
- Voltage at module power and ground pins: stable nominal battery voltage with key ON/cranking
- Resistance/continuity of data wiring between PCM and EBTCM: low resistance, no short to ground or battery
- Check for unexpected high current or short conditions on the data circuit (use bench/current clamp diagnostics if required)
Diagnostic algorithm
- Connect scan tool, record codes and live data; confirm P1573 and note any additional communication codes.
- Verify battery and charging system voltage. Low voltage can cause communication errors; correct if out of spec.
- Confirm EBTCM and PCM are present on the network. If EBTCM is missing, focus on wiring and power to EBTCM.
- Visually inspect connectors and wiring between PCM and EBTCM for damage, corrosion, or water intrusion. Repair any issues found.
- Check fuses and power/ground circuits for both PCM and EBTCM. Repair poor grounds or blown fuses.
- Perform continuity and short tests on the serial data wiring between modules (with battery disconnected when performing resistance checks). Repair any opens or shorts.
- If wiring and power/grounds are good, monitor the data line with an oscilloscope or a CAN/serial bus tool to verify message timing and waveform integrity. Compare to manufacturer reference if available.
- If a specific module fails to send or receive messages and wiring/power/grounds are confirmed good, consider swapping with a known-good EBTCM (if permitted) or consult manufacturer for module bench test/software update.
- After repairs, clear codes, perform relearns or module configuration per manufacturer procedures, then test drive and re-scan to confirm no return of the fault.
Likely causes
- Broken or shorted serial data line(s) between PCM and EBTCM
- Poor ground or low battery/charging system voltage causing communication errors
- Corroded terminal or bent pin at either module connector
- EBTCM hardware failure that prevents messaging
- PCM internal fault or connector problem
Fault status
Status
PCM detected a fault on the serial data circuit to the EBTCM — messages missing, invalid, or intermittent (communication fault).
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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