P1600

Code

SUZUKI P — Powertrain

PCM TCM Serial Communication Circuit Fault

Brand: SUZUKI

Type: P — Powertrain

Views: UK: 63 EN: 87 RU: 66

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Page language: EN

Open or short in the serial communication bus (CAN/LIN or manufacturer serial lines)
Corroded, loose or damaged connectors between PCM and TCM
Failed PCM or TCM (intermittent or permanent)
Low or intermittent battery voltage / poor ground
Water intrusion or physical damage to wiring harness
Aftermarket electronic device interfering with bus communications

Malfunction Indicator Lamp (MIL) or warning light illuminated
Stored P1600 (and possibly other network codes) in PCM memory
Harsh, erratic or stuck transmission shifting; transmission may default to limp mode
No communication with TCM when scanning with diagnostic tool or one module not visible
Intermittent drivability issues tied to network faults
Possible no-crank or cranking inhibited in vehicles that require module coordination

Connect a capable scan tool and read all stored and pending codes from PCM and TCM; note freeze frame data
Verify battery voltage and charge state (key ON, engine OFF and during cranking)
Check for presence of both PCM and TCM on the vehicle network with the scan tool (module list)
Perform a visual inspection of PCM/TCM connectors and wiring harnesses for corrosion, damage or water
Backprobe or measure CAN/serial bus voltages at the module connectors with key ON (see signal parameters)
Wiggle test wiring and connectors while monitoring bus and module presence to reproduce fault

CAN High (CAN H) idle ~2.5V (with activity pulses above ~3.5V depending on system) — check at PCM/TCM pins
CAN Low (CAN L) idle ~2.5V (with activity pulses below ~1.5V depending on system)
Differential CAN voltage when active typically ~1–2V (dominant state)
Serial TX/RX / LIN bus typical idle voltages and expected message activity (vehicle-specific)
Battery voltage (key ON) should be stable near nominal (~12–13V) during tests
Module ground continuity to chassis (near 0 ohms expected)

Record all DTCs from PCM and TCM, and view freeze frame data. Note code timestamps and related codes.
Verify battery voltage and charging system health. Recharge or replace battery if low. Clear codes and attempt to reproduce.
Use a scan tool to confirm whether PCM and TCM are present and communicating on the network. If one module is missing, focus on wiring to that module.
Visually inspect connectors, pins, and harness between PCM and TCM for corrosion, bent pins, water intrusion or repairs.
With key ON (engine OFF), measure CAN/serial bus voltages at PCM and TCM connector pins. Compare to manufacturer nominal values and between both module locations.
Backprobe TX/RX or CAN H/L while monitoring live data. Look for noise, missing messages, or open circuits. Perform wiggle test to find intermittent opens/shorts.
Isolate the circuit by disconnecting suspected aftermarket devices or non-essential modules that share the bus and re-test.
If wiring and connectors test good, consult service information for module programming status or TSBs. Reflash or update PCM/TCM software as recommended.
If module is confirmed non-responsive and wiring is verified, replace the faulty module per service procedure. After replacement, reprogram/configure modules and clear codes.
After repairs, road test and re-scan to ensure the fault does not return and transmission and engine operate normally.

Damaged wiring or chafed insulation on the CAN/serial lines
Corroded or pushed-out pins at PCM/TCM connectors
Faulty ground at PCM or chassis ground point
Faulty TCM (no response on bus) or PCM transmit/receive driver failure
Recent battery replacement, jump start or module reflash that altered network configuration
Loose or intermittent battery connection causing brown-out conditions

⚠️ Status

PCM detected loss or corruption of serial communication with the TCM. Check communication bus, connectors, ground and module presence.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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P1600 — PCM TCM Serial Communication Circuit Fault