B1478
Power Window One Touch Up/Down Activated Simultaneously
Body Chassis/Safety Power Window Control 🟢 Low — Fix at next service
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What This Actually Means
In plain language — no jargon

Your car's power window system detected both the up and down buttons being pressed simultaneously, which shouldn't happen during normal operation. Think of it like trying to push a door open and closed at the same time—the system caught a conflicting command.

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Symptoms You May Notice
3 known symptoms for this code
Power window operates erratically or becomes unresponsive
One touch up/down feature stops working correctly
Window control module warning light or body control module fault display
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Embedded Systems Insight
What the ECU/ECM is actually computing

The body control module monitors the switch input voltage signals from the power window control switch. It detects when both up and down signals are active simultaneously, which indicates a short circuit, stuck switch, or wiring fault. The ECU expects only one command at a time under normal conditions.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Switch Signal State Only one button active (up OR down) at any given time Both up AND down signals detected simultaneously
Signal Voltage Isolated high/low states per button Conflicting voltage levels indicating cross-contact or short
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Power window switch contact cleaner
Clean the switch contacts with electrical contact cleaner to remove debris causing simultaneous signal detection.
2
Power window master switch assembly
Replace the faulty switch if cleaning doesn't resolve the issue, as internal contacts may be permanently shorted.
3
Window wiring harness
Inspect and repair any pinched, damaged, or shorted wiring in the door harness between the switch and body control module.