2003 Chevrolet Trailblazer, Blower Not Working Any Speeds, Brake & ABS Lights On

This 2003 Chevrolet Trailblazer came in with the complaint that the blower would not work on any speed and that the Brake and ABS lights stay on. Since I have seen this problem before, I knew right where to go to test. then ignition switch. The first thing that has to be done is to remove the tilt lever handle. Some just pull straight out but this one was a little difficult so I used a screwdriver for leverage.

After the lever is pulled past the detent it comes out easily the rest of the way.

Now the trim panels under the dash have to come out. Two screws, 7mm,  for the black hush panel under the dash.

With the black panel down there are two screws that hold the bottom of the knee bolster panel.

Two at the top of the panel.

Then the panel will unsnap. Someone has already been here. The spring clips are missing.

Now there is a soft piece of rubber trim at the rear of the lower cover. It needs to be worked loose of the lower cover. Then carefully unsnap the lower cover and work it loose from the column and the soft rubber piece in the rear. Some models may require removing the steering wheel to get the cover off and some may have screws in the underside of the lower cover.

Now that the switch wiring is exposed. Check for constant battery power on the red wire as shown below.

Turn the ignition on and check for power on the orange wire. We have just diagnosed a faulty ignition switch.

To remove the switch, I first gently pulled the wiring for the key buzzer and /or antitheft antenna out of the retainer as shown below.

There is a special GM tool for releasing the ignition switch retainers but I just use a couple of pocket screwdrivers. There are two white spring loaded pins that have to be pushed in to allow the switch to come out.

You can now see the two pins exposed as I pulled the switch down.

GM says to  remove the lock cylinder and use a tool to fully rotate the inner mechanism but I don’t bother. I just make sure the ignition is off. Key out. Pull the switch down and note the position of the gear teeth. DO NOT rotate the gear teeth. Adjust the teeth on the new switch to match the old switch position.

The wiring harness lock is a little difficult to release. You are supposed to depress the locking tab.

I was having a problem so wedged my screwdriver between the switch housing and lifted it instead. If something breaks, I would rather break an old part that is being replaced, instead of the latch on the harness connector. Makes sense, right?

I checked the harness connector for damage and all was okay.

Maybe a better view of the plug in connection to the switch.

I adjusted the gear teeth to the same position. I also compared them one behind the other to check the alignment.

The new switch on the right with the gray cover. To purchase the new updated ignition switch please click here.

Slide the new switch into place until the spring loaded locking tabs click into place.

Plug the wiring harness back up to the switch. Positioned the rest of the wiring back into the retainer on the side of the switch.

Cranked the engine and checked the blower and all is well. Time to finish installing the rest of the parts.

To see the video for this repair please click here.

This ignition switch fits the following vehicles, however the repair procedure may vary between these vehicles.

2001-2005 Pontiac Aztek
2002-2004 Oldsmobile Bravada
2002-2007 Buick Rendezvous
2002-2009 Chevrolet Trailblazer
2002-2009 GMC Envoy
2003-2006 Cadillac Escalade
2003-2006 Chevrolet SSR
2003-2006 Chevrolet Suburban
2003-2006 GMC Savana
2003-2006 GMC Yukon
2003-2007 Chevrolet Silverado
2003-2007 Chevrolet Express
2003-2007 GMC Sierra
2003-2007 Hummer H2
2003-2008 Isuzu Ascender
2004-2006 Chevrolet Tahoe
2005-2007 Buick Rainier
2006 Chevrolet Avalanche
2006-2009 Saab 9-7X

58 discussions on “2003 Chevrolet Trailblazer, Blower Not Working Any Speeds, Brake & ABS Lights On”

  1. So this happen to my 04 trailblazer I installed the new ignition switch but when I connected the battery and turn the key it. All the light come on but the engine doesn’t start.

    1. Assuming that your Trailblazer had no cranking issues before replacing the electrical portion of the ignition switch, then you simply have the timing of the gear teeth off by a tooth or two. In the article I talk about having the ignition off and the key out of the ignition before removing the ignition switch. I then show several pictures of how the gear teeth of the new switch should be adjusted to match the old switch. Those pictures will give you an idea of where the wider notch in the gear teeth should be positioned. You can also just remove the new switch and adjust the gear rotation by one notch and reinstall until you get the timing correct.

        1. Yes, the white plastic gear in the ignition switch moves. It will be up to you to get it in the right position. As mentioned earlier you can match it up to the pictures near the end of this article. You can use your fingers or a small screwdriver to move the gear teeth.

  2. I had this very same issue on my 2007 Chevy Trailblazer. Ignition switch replaced but I am pretty sure that the gear teeth might be off slightly – I did have a few issues with it putting it back in and not lining up correctly to start etc….My problem now is that when the key is in the off position thee car is off but my dash lights and the light under the park (P-R-N-D) indicator does not go off. Lights and inner dome lights go off. HELP please? Should I remove the ignition switch again and toggle the gears a bit to see if that fixes the situation?

    1. That would be the first thing I would start with. Remove the ignition switch (electrical portion) with the key in the off position and the key removed. Either align the gear as shown in this article or reconnect it electrically and slowly move the gear teeth until the symptoms clear up. Then reinstall the switch and see if all of the problems are gone.

  3. I have a 2005 GMC envoy… I have the amber 4 wheel drive inop light on the dash…..If I turn the blower to any position except off, I get te antiskid and red brake light on….. Would a faulty ignition switch cause this too?

    1. It is very likely that the ignition switch is causing all of those problems. It is a simple test as outlined in the article. Remove the steering column covers and check for ignition power on the Orange wire with the ignition on. Assuming the engine cranks and runs and there is no power on the Orange wire the ignition switch is faulty. This test should be done with the blower switch turned on.

  4. Just a quick question Sparky,

    I have a 2002 Envoy .. 2 years ago this problem started – dash lights would come off and on – ABS, seatbelts light etc . These lights would flash on and off and go back to normal after a couple of starts – very seldom the gauges would fluctuate and once just cut out for a few minutes then came back on. Today the same thing happened but upon stopping and restarting – the dashboard is now dead – no lights and no gauges. the truck runs fine and i’ve never had a problem with the blower, I just went out and started it again, gauges and lights came on and then flashing a bit. Shut it off and then nothing on the dash – no lights or gauges. then shut it off and started again and the lights and gauges worked began flashing a bit and some gauges went off and came back on. When i turn the key off sometimes the gauges stay on for about 5 seconds then they shut off. Does this like it could be the ignition switch? Thank you From Dave in Nova Scotia

  5. That would mean that either the BCM is faulty and keeping the lights on or there is a short to ground on any one of several control wires. At this point you will really need the use of a Tech 2 scan tool. It would make diagnosis a ton easier and if the BCM needs to be replaced a Tech 2 must be used for BCM Setup and Programming.

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