Lost Communication With Body Control Module
What it means
The body control module (BCM) runs most cabin and body electrical functions, such as lights, wipers, locks and windows, and on many vehicles takes part in the key and immobilizer system. This code sets in another module when BCM messages stop arriving. Symptoms vary a lot with the functions the module handles on each vehicle, and can include a no-start.
Symptoms5
- Exterior or interior lights, wipers or turn signals not working or acting strangely.
- Central locking or the remote key not working.
- No start on vehicles where the BCM helps verify the key.
- Several warning lights or messages in the cluster.
- Battery drain while parked in some cases.
Possible causes6
- Weak battery or loose terminals.
- Blown BCM power fuse; there are usually several.
- Water in the module or its connectors, especially when it sits under the dash near the windshield drain or on the floor.
- Poor module ground connections.
- Open or shorted network wiring to the module, or an accessory wired incorrectly into its circuits.
- Internal BCM failure.
How to diagnose5
- Test the battery and terminals and measure voltage, since low voltage is a common cause of network codes.
- Try to connect to the BCM with a scan tool; if it does not respond, check all its fuses, power and ground.
- Inspect the module and connectors for water or corrosion, and check the drains near the windshield and doors.
- Check any add-on devices such as alarms, remote start or extra lighting to make sure they have not damaged the wiring.
- Measure network line resistance and voltages and compare them with the manufacturer specification.
How to fix6
- Charge or replace the battery and clean its terminals.
- Replace the blown fuse and find why it blew.
- Dry the module, fix the water leak, and clean or repair corroded connectors.
- Remove incorrectly installed accessories and repair damaged wiring.
- Replace the BCM if proven faulty and program it with the manufacturer tool; the keys may need to be reprogrammed too.
- Clear codes in all modules and test the lights, locks and starting.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
The cost is low for a battery, fuse or ground, rises when water damage must be repaired, and reaches the upper end if the BCM must be replaced and programmed along with the keys.
Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026
Frequently asked questions
Can this problem stop the car from starting?
Yes, on some vehicles, because the BCM takes part in key verification and the immobilizer. If it drops off the network, the engine may crank but not start, or not crank at all.
Why is the BCM so often damaged by water?
On many vehicles it sits under the dash or on the floor, so blocked drains or leaks from the windshield or A/C can reach it. Fix the water source before installing a new module.
Can I install a used BCM?
On some vehicles, yes, but it usually needs programming to match the VIN and keys. Without it, some functions may not work or the engine may not start.
This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.
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