Mechanics

CHEVY FAN SWITCH & ABS/BRAKE LIGHT

2004 Chevrolet Trailblazer

Electrical problem
2004 Chevy Trailblazer 6 cyl Two Wheel Drive Automatic 68500 miles

The fan switch only works on setting 5 with the abs/brake lights going crazy and dinging. I read that you only need to replace the resistor for the blower. I have replaced the blower motor resistor under the glovebox, disconnected the battery and reconnected; problem is the repair only worked for one day, now it is back to the same issue. How can I resolve this issue w/o taking it to the dealer for $100-$1,500 for repairs?
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Pacphnmn
May 19, 2008.




Try following this bulletin. Subject: ABS Red Brake SVC and 4WD Light On HVAC Blower Inoperative

Models: 2004-2007 Buick Rainier

2002-2008 Chevrolet Trailblazer models

2002-2008 GMC Envoy models

2002-2004 Oldsmobile Bravada
Diagnose for loss of battery voltage to the rear fuse block on circuit 300 ORN for the following fuses: Note: Prior to proceeding forward with the information below, it is important to verify the voltage as indicated however it is equally important to verify the integrity of each circuit. This can be achieved by performing a voltage drop test or by adding a device to each circuit that will supply sufficient load to verify the circuits integrity.

HVAC 30A, 4WD 15A, HVAC 1 10A, BRAKE 10A, TBC RUN 3A.

Check circuit 300 ORN for battery voltage when the ignition key is in the RUN position.
Check for battery voltage at the rear fuse block under the rear seat Connector C1 pin D9.
If battery voltage IS NOT present at these locations, check for voltage at the ignition switch pin G for circuit 300 ORN.
If battery voltage IS present at the ignition switch pin G, check circuit 300 for an open.
If battery voltage IS NOT present at the ignition switch pin G, replace the ignition switch. Please post back with the findings.

Brian 1
May 19, 2008.
Thank you for the response, however, it looks like I would need to get a manual or schematic of the Trailblazer in order to troubleshoot the issue.
I also read in a blog entry that someone mentioned that it might need to be taken to the dealer to have the computer " sync'd" up with the controls. Do you know anything about that?
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Tiny
Pacphnmn
May 20, 2008.
I've never heard of it being sync'd up, I don't even know what that is?You should not have to do anything with the computer. This is a pretty straight forward problem with a staight forward fix. Post back with what you find.

Brian 1
May 20, 2008.
Brian 1,

The problem was resolved via checking the voltage on pin G on the ignition switch -no voltage present. Replaced the ignition switch per TSB, system running well. Set of contacts on old switch had noticable heat marks on them.

Thanks again for your help.

Tiny
Pacphnmn
Jun 10, 2008.

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