Questions & Answers
Got a PO449 code on an 09 Colorado. AutoZone gave
There are two vent/purge valves - one on the engine that takes vapor from the gas tank and cycles it into the intake manifold. The other one is connected by a hose to the vapor canister. I don't know which one you bought, but it can't hurt to replace both - the one that fails most often is the one connected to the canister and is usually mounted under the vehicle at the back. It often fails due to road contamination getting into the solenoid.
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Make and model, year, engine, transmission? 2wd/4wd, ever been wrecked, etc.
could be drivetrain parts such as c.v. or U joints.
could be fuel system clog somewhere.
could be a bad sensor.
We will need more detailed information.
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2000 Silverado will not start!
It sounds like you have a ground problem. Have you checked to see that the "new" battery is fully charged? Have you checked to see if the starter motor is getting current when you try to start the truck? Have you checked to see if the battery cables and terminals are corroded, or the cables themselves corroded at any point? You also might have an ignition switch problem due to age or use. You also might have a computer problem that is keeping the circuits from connecting properly. If you have a OBD II scanning tool, it might well tell you exactly where the problem is. Scanners are inexpensive and available almost everywhere. I bought mine through Amazon for less than $25 including shipping.
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4wd auto shift does not engage 4wd.
for 4wl need to be stopped and put in neutral or park it wont actuate while driving [ blinking light indicates failure to engage ] 4wd hi can do while driving --if fails also then check and test for actuator sticking --control module --or transfer case failure
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2000 chevy siverado z71 4x4 not working
Yes we can ! With the light on and or flashing , DTC'S - diagnostic trouble codes are stored in the 4X4 control module . Have the codes check , not at auto zone or any other parts stores . There code reader tool will not pull this codes . Need to take to a qualified repair shop . Testing also needs to done , not guessing an throwing parts at it . This 4X4 system can set a number of codes .
DTC B2725 ATC Mode Switch Circuit Malfunction
DTC C0300 Rear Speed Sensor Malfunction
DTC C0305 Front Speed Sensor Malfunction
DTC C0308 Motor A/B Circuit Low
DTC C0309 Motor A/B Circuit High
DTC C0310 Motor A/B Circuit Open
DTC C0315 Motor Ground Circuit Open
DTC C0323 T-Case Lock Circuit Low
DTC C0324 T-Case Lock Circuit High
DTC C0327 Encoder Circuit Malfunction
DTC C0362 4LO Discrete Output Circuit High
DTC C0367 Front Axle Control Circuit High
DTC C0374 General System Malfunction
DTC C0376 Front/Rear Shaft Speed Mismatch
DTC C0387 Unable to Perform Shift
DTC C0550 ECU Malfunction
DTC C0611 VIN Information Error
DTC C0387 Unable to Perform Shift
The transfer case encoder is a switch that converts a shaft position, representing a mode or range position, into electrical signals for use by the transfer case shift control module. The encoder houses 4 Hall effect sensors that are used for channels P, A, B, and C. These sensors provide a path to ground, when a magnet, (part of the Motor Encoder), passes over them.
The transfer case shift control module supplies an 8 V reference and a ground circuit for the encoder hall effect sensors to function.
The transfer case shift control module supplies current limited 5 V on all the channels, thus as these channels are pulled to ground, the module can interpret the location of the transfer case shift position.
This DTC detects that the transfer case is unable to successfully complete a shift to a requested mode or range.
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Heat transfer stuck
our temperature control actuator is bad. It's a little motor that moves the temp door. They are about $70 at the dealer. To change it you need to remove the knee trim panel on the passenger side (3 screws, 7mm socket). The actuator is in the center above the transmission hump. It has one harness plugged into it and 2 screws (5.5 mm). Take the screws out and it should drop straight down. Align the actuator with the lever on the door and put the screws in. Plug the harness back in. Turn your temp control to cold and remove the HVAC 1 fuse. Should be in the fuse panel on the drivers side of the dash. Turn your key to run and leave it on for at least 1 minute. Turn your key back off and put the fuse back in.
P.S. The trim panel is a PITA to get off, so while you have it off check to see if you have the cabin air filters and change them while you are under there.
Also there is an article in the Tech Corner on changing the cabin air filters.
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What do the capped lines on the ehcu
Bleeder screws , If you haven't replaced the unit you don't need to do anything with them . Don't need to have the vehicle running , just bleed the brakes normally . If you have replaced the Electro-Hydraulic Control Unit
you need a factory scan tool to cycle the unit solenoids
• Use the two-person bleed procedure under the following conditions:
- Installing a new Electro-Hydraulic Control Unit (EHCU) or new Brake Pressure Modulator Valve (BPMV).
- Air is trapped in the valve body
• Do not drive the vehicle until the brake pedal feels firm.
• Do not reuse brake fluid that is used during bleeding.
• Use the vacuum, the pressure and the gravity bleeding procedures only for base brake bleeding.
Raise the vehicle in order to access the system bleed screws.
Bleed the system at the right rear wheel first.
Install a clear hose on the bleed screw.
Immerse the opposite end of the hose into a container partially filled with clean DOT 3 brake fluid.
Open the bleed screw 1/2 to one full turn.
Slowly depress the brake pedal. While the pedal is depressed to its full extent, tighten the bleed screw.
Release the brake pedal and wait 10-15 seconds for the master cylinder pistons to return to the home position.
Repeat the previous steps for the remaining wheels. The brake fluid which is present at each bleed screw should be clean and free of air.
This procedure may use more than a pint of fluid per wheel. Check the master cylinder fluid level every four to six strokes of the brake pedal in order to avoid running the system dry.
Press the brake pedal firmly and run the Scan Tool Automated Bleed Procedure. Release the brake pedal between each test.
Bleed all four wheels again using Steps 3-9. This will remove the remaining air from the brake system.
Evaluate the feel of the brake pedal before attempting to drive the vehicle.
Bleed the system as many times as necessary in order to obtain the appropriate feel of the pedal.
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Does the vehicle start an run ? If it does ,the brain as you call it is working fine . The check engine light has nothing to do with the PCM /ECM sensing problems .You probably should take your vehicle to a qualified repair shop .
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