So Fix it

Drivers depend on their instrument gauges to monitor the cars speed, as well as the amount of miles driven. But for some vehicles, such as the Chevy Trailblazer, problems can arise that affect the gauges functioning.

Identification

A Trailblazers gauges are arranged in an instrument cluster. Normally, the cluster includes the speedometer, fuel and coolant temperature, motor oil temperature, battery voltage and a tachometer.

Features

Many symptoms can point to a faulty instrument gauge, or even the entire cluster. Individual gauges can give intermittent information or stop working completely. Other gauges can look like they are functioning correctly, but are producing incorrect information, such as the speedometer reporting 60 mph when the car is actually traveling at 45 mph.

Prevention / Solution

Many repair facilities can fix your gauges. Depending on the system, some gauges have their motors replaced, while some just need simple calibration. If the damage to the gauge cannot be repaired for a reasonable price it may be best to replace the unit.

The Chevrolet TrailBlazer is a sport utility vehicle that was a trim level of the Blazer from 1999 to 2001. General Motors made the Trailblazer a separate model in 2002 until the end of its production in the United States during 2008. All 2006 Trailblazers have an anti-lock braking system controlled by a microprocessor known as a brake controller, or Electronic Brake Control Module (EBCM). This device adjusts the braking force to each wheel during emergencies to prevent the wheels from locking.

Instructions

1

Remove the cable from the negative terminal of the battery with a socket wrench to prevent the discharge of electricity when you remove the EBCM. Clean the area around the EBCM in the engine compartment on the driver side of the engine. This will keep the braking components from becoming contaminated.

2

Detach the connectors for the electrical wiring on the EBCM. Disconnect the four mounting screws on the EBCM with a T 25-Torx tool, and discard the screws. Pull the EBCM gently to remove it from the Brake Pressure Modulator Valve (BPMV).

3

Clean the mounting surfaces on the BPMV with a clean shop towel to avoid contaminating the new EBCM. Fasten the new EBCM to the BPMV with a T-25 Torx tool, using new mounting screws. Tighten the mounting screws to 39 inch-pounds, working in an X-pattern. Attach the electrical connectors to the EBCM.

4

Connect a scan tool to the vehicles data link connector which is under the instrument panel to the left of the steering wheel. Perform the tire size calibration function according to the scan tools instructions, and disconnect the scan tool. Connect the cable to the negative terminal on the battery using a socket wrench.

During the life of your Trailblazer, the bulbs in the headlight may burn out and need to be replaced. In order to replace these bulbs, the headlight assembly needs to be removed from the front of the vehicle. Removing the headlight assembly allows you to access the bulbs, which are connected to the sockets on the electrical connectors. Before starting this project, the bulbs will need to be purchased from an auto supply store.

Instructions

1

Open the drivers side door and pull the hood release lever to release the hood. Lift the hood up and set the support bar.

2

Find the snap clips that are used to secure the grill to the front of the vehicle. Pry the retainer clips with the flat head screwdriver to release them. Pull the grill off of the vehicle.

3

Find the retainer clip that is located in the upper left or right of the headlight. Push up on the retainer clip with the flat head screwdriver. Look under the fender, beneath the headlight, and locate the second retainer clip. Push this retainer clip up with the screwdriver.

4

Press the release tab that is on the back of the headlight assembly. Pull the electrical connector out of the headlight. Pull the headlight assembly out and set it on a bench or table.

5

Pull off the two rubber caps on the back of the headlight assembly to expose the headlight bulbs. Turn the socket counterclockwise and pull the bulb out of the headlight. Lift up the tab on the electrical harness and then pull the bulb out of the socket.

6

Insert a new bulb into the socket and then place the bulb back into the headlight. Turn the socket to the right or clockwise to lock it in place. Set the rubber caps back in place over the electrical connector.

7

Set the headlight back in place and then reconnect the electrical connector. Push the upper and lower retainer clips back in place to secure the headlight.

8

Set the grill back in place and then push on it firmly to secure the retainer clips to the frame.

The 2004 Chevy Trailblazer base model came with a 4.2-liter inline six-cylinder engine and a four-speed automatic transmission. Your catalytic converter is located between the exhaust manifold and the muffler. A faulty catalytic converter can result in poor performance and higher emissions levels that will cause you to fail an emissions test. Replacing your catalytic converter is a straightforward task, but the transmission mount has to be removed because of the length of the catalytic converter assembly.

Instructions

Removal

1

Park the vehicle on a level surface and set the parking brake. Lift the front of the vehicle into the air with a floor jack and place jack stands under the front frame rails. Lower the vehicle until it rests securely on the jack stands. Allow the engine and exhaust to cool completely before continuing.

2

Position yourself under the vehicle so that you can clearly view the catalytic converter and its connection to the exhaust manifold. Locate the front oxygen sensor that is positioned just after the first flange and disconnect the pigtail from the wiring harness. Follow the catalytic converter piping after the converter to find the rear oxygen sensor. Disconnect the rear oxygen sensor pigtail from the wiring harness.

3

Place the oxygen sensor socket over the front oxygen sensor so that the pig tail extends through the slotted portion of the socket. Rotate the sensor counterclockwise with a ratchet to remove the sensor from the exhaust. Apply heat with a propane torch around the base of the sensor, if it is difficult to remove. Repeat for the rear oxygen sensor and label each one accordingly; they are not interchangeable and must be installed in the same position.

4

Place one jack stand at the rear and one under the front of the converter assembly, and elevate them until they make contact with the converter assembly. Remove the nuts securing the converter assembly to the exhaust manifold with a ratchet and socket. Remove the nuts securing the converter assembly to the rear muffler pipe.

5

Place a floor jack under the transmission and place a small block of wood on the jack arm. Raise the jack until the wood makes contact with the case of the transmission, but do not apply any upward force. Examine the transmission support that runs between the two frame rails to find the two center access holes. Remove the bolts securing the transmission mount to the transmission support with a socket and ratchet.

6

Remove the bolts securing the transmission support to the frame rails. Lower the transmission support from the vehicle and set it aside. Remove the bolts securing the transmission mount to the base of the transmission. Remove the catalytic converter and transmission mount from under the vehicle.

7

Pry the rubber hangers from the old catalytic converter assembly with a pry bar and set them aside. Set the transmission mount aside, with the rubber hangers attached.

Installation

8

Examine the rubber hangers for any damage or wear and replace as necessary. Install the transmission mount, with the rubber hanger bracket attached, to the transmission. Install the mounting bolts and tighten to 48 foot-pounds with a torque wrench.

9

Set the catalytic converter assembly onto the jack stands so that the flanges at both ends meet up with the exhaust manifold and muffler assembly. Lift the catalytic converter assembly as necessary and install the rubber hangers at the transmission mount to the metal hangers on the converter assembly.

10

Lift the transmission support into place between the frame rails and install the retaining bolts. Install the transmission mount to transmission support nuts through the access holes and tighten to 35 foot-pounds.

11

Install a new gasket at the front and rear of the converter assembly. Slide the converter assembly rear flange over the studs for the muffler pipe. Install the rear mounting nuts hand tight. Install the front converter flange to the exhaust manifold and install the mounting nuts hand tight. Tighten the mounting nuts for both flanges one turn at a time until they are tightened to 33 foot-pounds.

12

Remove the jack stands from under the converter assembly. Clean the oxygen sensor threads with a wire brush and apply copper anti-seize to the threads. Install the both oxygen sensors to the converter assembly until hand tight. Tighten both sensors to 30 foot-pounds with a torque wrench and oxygen sensor socket. Plug the oxygen sensor pigtails to their respective wire harness connectors.

13

Lift the front of the vehicle off the jack stands and remove the jack stands from under the vehicle. Lower the vehicle to the ground and remove the floor jack.