C1802

Code

Generic C — Chassis

Chassis Control Module Communication Fault

Brand: Generic

Type: C — Chassis

Views: UK: 13 EN: 24 RU: 17

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Page language: EN

Malfunction indicator lamps for ABS/traction/stability or chassis control illuminate
Loss of stability/traction control functions or inconsistent behavior
Related modules report communication errors or go into limp/default mode
Stored C1802 and possibly other U- or C-network codes
No chassis module data/parameters visible on scan tool or intermittent message stream

Read all stored and pending codes from all modules with a capable scan tool; record freeze-frame and network messages
Check battery voltage and charging system; verify >12.4 V with key on and engine off
Visual inspection of CCM connector and wiring harness for damage, corrosion, pin push-out, or repairs
Inspect fuses and relays supplying CCM power and accessories
Check for other modules reporting network errors (helps localize bus segment)
Backprobe or access CANH/CANL at CCM and a nearby module to compare signals

CAN bus idle: CANH ≈ 2.5 V, CANL ≈ 2.5 V (recessive)
CAN bus dominant: CANH ≈ 3.5 V, CANL ≈ 1.5 V (differential ≈ 2.0 V)
Termination resistance: approx. 60 ohms across CANH–CANL (two 120Ω resistors in parallel)
Typical module supply: nominal battery voltage (~12 V with key on), low supply may cause comm faults
Bus load/activity: continuous periodic frames when system is healthy; complete silence or burst errors indicate fault

Connect a professional scan tool and read all modules; note C1802 occurrence, timestamps and related U-codes.
Check battery voltage and charging; ensure stable supply. Replace or recharge battery if low.
Inspect CCM connector and nearby harness for corrosion, bent pins, heat damage, or water intrusion. Repair damaged terminals.
Verify fuses/relays feeding CCM and test for proper +12V and ground at the CCM power pins.
With ignition ON, backprobe CANH and CANL at CCM and a known-good module. Verify idle voltages (~2.5 V), dominant voltages during activity, and approx. 60 ohm termination.
If bus voltages are incorrect, isolate wiring sections: measure resistance from each CAN line to ground and to battery to check for shorts, and unplug modules sequentially to find which connection causes bus restoration.
Use an oscilloscope or high-speed CAN bus logging-capable scan tool to look for noise, bus-off frames, or malformed packets. Record findings.
Repair identified wiring/connectors, replace faulty termination resistor(s), or correct power/ground faults. Clear codes and retest driving cycle to confirm permanent repair.
If wiring and bus are good and problem persists, consider reprogramming or replacing the CCM only after confirming the fault follows the module.
After repair, rescan all modules and perform functional tests of ABS/ESC/traction systems.