LAMP CONTROL MODULE INPUT SIGNAL LOW
The lamp control module is not receiving the expected signal voltage.
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What it means (plain English)
The lamp control module, which manages all the lights on the vehicle, isn't getting the signal it needs to operate correctly. It's supposed to see around 5 volts from the switch when the lights are turned on, but it's getting less than 0.5 volts instead.
What the computer is actually seeing
The lamp control module monitors inputs from various switches and sensors to determine when lights should be on or off. If the signal from the light switch is too low, it throws this code.
What a healthy reading looks like
Expected signal voltage is between 4.5 to 5.5 volts when lights are activated. A reading below 0.5 volts indicates a fault.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 1Check the vehicle's battery and fuse connections. Ensure they are all secure and in good condition. Decision Point: If any issues found, repair and retest; if all good, continue.
- 2Inspect wiring harness connected to the lamp control module for wear or damage. Look for short circuits or open wires. Decision Point: If damage is found, repair and retest; if none, proceed.
- 3Check connector integrity at lamp control module and light switch for corrosion or loose connections. Decision Point: If corrosion or loose connections are found, clean or secure and retest; if okay, go to next step.
- 4Test voltage at the light switch connector while operating the switch. Expected voltage is between 4.5 to 5.5 volts with the lights on. Decision Point: If within range, replace lamp control module; if not, investigate the switch or wiring further.
Common causes
- Damaged wiring in the circuit to the lamp control module
- Faulty lamp control module
- Corroded or loose connectors
- Faulty light switch or control switch
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's generally drivable, but you may have issues with lights functioning properly, which can affect safety.
Will this code come back after resetting?
If the underlying issue is not resolved, the code will likely reappear.
Why is this code paired with other codes?
Multiple codes may indicate a shared issue in the circuit, like a wiring fault or common ground problem.
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