20 Most Recent 2005 GMC Envoy - Page 3 Questions & Answers

The headlamp driver module (HDM) is an electronic module that provides electrical power to the vehicle low beam headlamps. The HDM is controlled by a pulse width modulated (PWM) ground signal from the body control module (BCM). The BCM determines the desired lamp intensity using the ambient light sensor, multifunction switch and the park brake switch as inputs. In general, the HDM will operate in 1 of 3 modes: Your best bet have it checked by a qualified repair shop ! May have DTC'S diagnostic trouble codes . DTC B2575 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 pulse width modulated (PWM) ground signal to the low beam headlamp driver module through the low beam headlamp driver module control circuit. The low beam headlamp driver module will illuminate the headlamps, adjusting the intensity based on the PWM signal received. DTC B2580 Headlamp High Beam Control Circuit DTC B2645 Ambient Light Sensor Circuit 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.

Does your husban know how to do electrical testing ? Find a wiring diagram , voltage drop test the circuit to find what's missing power or ground . The hit could have damaged wiring or ground . You can find a wiring diagram at http://www.bbbind.com/free_tsb.html Also watch youtube video on Mastering Voltage Drop Testing with Pete Meier and Jerry Truglia .

I am only able to shoot you a guess on this and hopefully it steers you the right direction. I believe your vehicle went into limp mode. This can be from over heating to emission problems to a bad piston. The vehicle does this to protect itself. The cheapest way to diagnose this one is to take it in. Remember, having it diagnosed does not mean you cannot fix it yourself. Just pay the fee and take it home if it is something you want to tackle.

Try looking either very right or very left end of dash, you have to open the door to see the plastic panel. Pop off the panel and there are the fuses.

https://youtu.be/V8ijhriM44g

Yes reverse thread.

There is no reset button on envoys ! Ford has this inertia fuel shut off switch, not GMC or any GM or Chrysler ,dodge , jeep ! Some asian vehicles have it .

I just went thru the same thing with my Silverado. Ok first thing to do is check your fuel pressure. You can rent the pressure testing gage at autozone. Usual pressure needed is 50lbs. Next thing to check is your fuel pressure solenoid. It's a good guess that it's one of those two things. The best investment you can make is to buy the little computer/engine code reader. You dont have to buy the high dollar one, the one I use was only 60.00. Best investment ever. Very easy to use, it plugs in usually just to the left of your steering column.

Try using the door key to lock and unlock the drivers door.

You have to have a diagnostic meter to reset the light. Look for them in auto parts stores and on line. They are expensive.

No, unless the front bearing on the pump wobbles a lot.

The park switch inside the wiper motor gear box is bad.

Not necessarily. Once the fan is off , remove the plastic fan shroud and you should be able to get to all the bolts.

The circuit breaker for the windows may be open, the window switches may be bad, the body control module may be bad, the motor may be bound up and the regulator may need to be lubricated

Inside the transmission there is a mechanical device called a parking pawl. When the transmission is put in to park this L shaped chunk of metal locks the output shaft from turning. This Pawl can break and become useless in stopping the vehicle from moving without the park brake on. What all this means is the pawl inside your transmission has stopped working. The part needs to be replaced to restore its operation.

Check the wiring harness on the back of the radio to see if it's loose. If you have a Bose system, the amplifier may be going bad.

The automatic idle control module isn't working.