Question about 2006 Chevrolet Colorado
Dash switch causes park/running lights to work. High/low switch will only illuminate the dash high beam indicator. The vehicle was parked overnight and the check engine light was on without key inserted in ignition. Do not have code reader so haven't checked code yet. It also has daytime running lights.
Hello. It seems your Chevrolet has either faulty headlamp relay(s) or its headlamps are connected in series; if one don't light, neither will the other one. I can't explain why the 'CHECK ENGINE' light was still on while your truck's engine was off and key was out of ignition switch. Good luck and keep me informed; if you want to.
Posted on Sep 13, 2021
Your truck 4 wheel drive or 2wd ? What engine ?
Major components of this system are the body control module (BCM), headlamp relay, beam select relay, ambient light sensor, headlamp and panel dimmer switch, turn signal/multifunction switch, park brake switch, and the low and high beam headlamps.
Hooking up a factory or someother type professional scan tool (not a code reader , these will not read BCM codes) an check DTC'S diagnostic trouble codes in the BCM .
DTC B2575 Headlamp Control Circuit
When the body control module (BCM) senses a request for headlamp or daytime running lamp (DRL) illumination, the BCM sends a ground signal to the headlamp relay through the low beam headlamp relay control circuit. The headlamp relay will illuminate the low beam headlamps.
• DTC B2582 Headlamp High Beam Control Circuit Low
• DTC B2583 Headlamp High Beam Control Circuit High
When the body control module (BCM) receives a ground signal from the multifunction high beam or flash to pass (FTP) switch commanding to illuminate the high beam headlamps, the BCM will energize the high beam relay by grounding the high beam relay control circuit.
Also having a professional scan tool you can bi-directly control componets (turn them on an off ) ,to see if the BCM can control that componet .
Install a scan tool.
Turn ON the ignition, with the engine OFF.
With a scan tool, command the high beam relay ON and OFF.
Does the high beam relay turn ON and OFF with each command?
DTC B2602: Daytime Running Lamp Control Circuit Low or Open
DTC B2603: Daytime Running Lamp Control Circuit High
The daytime running lights (DRL) relay is controlled by the body control module (BCM). Battery positive voltage is applied to the relay coil at all times. The BCM grounds the DRL relay control circuit in order to turn ON the DRL relay illuminating the low beam headlamps at a reduced intensity.
• DTC B2647 Ambient Light Sensor Circuit Low
• DTC B2648 Ambient Light Sensor Circuit High
The body control module (BCM) monitors the ambient light sensor signal circuit in order to determine if the daytime running lights (DRL) or the auto headlights (ALC) should be turned ON in the AUTO mode. When the BCM senses the ambient light sensor signal voltage is between 1.75-4.9 volts, either the DRL will be commanded ON or the ALC will be commanded ON depending upon the amount of light received by the sensor.
And as far as the check engine light being on with the key off and out of the vehicle ,you have to have a electrical shot somewhere in the instrument cluster . The way the Check engine light works is by a command from the PCM/ECM over the class 2 serial network .Instrument cluster has a microprocessor inside which deciphers these messages . The ABS - module would send a message for ABS light to be turned on. battery light same thing . All the warning lights work that way .
So you mite want to have a qualified repair shop check it .
Posted on Sep 16, 2021
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