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2002 envoy_slt
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16 Posts
Discussion Starter · #1 ·
Howdy fellas :tiphat

I am about to change out my trashed brake booster. Looks pretty straight forward (famous last words). From inside the cab-I know that you have to pry off the clip retaining the brake light switch and the booster pushrod to the pin on the brake pedal.

This looks to be the trickiest part of the swap. Was wondering if maybe someone who has done this before had any tips for getting this switch off. Any brake booster removal tips are welcome. Thanks!
 

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2002 chevy trailblazer_lt
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Sure do just replaced mine today! The clip is actually fairly simple, you need to take down the black plastic cover under the dash (two 7mm bolts on either side hold it up). Then find the lip of the clip and pull it down use a flat head screwdriver and lift the piece lying on top of the bolt then push the clip upwards.
I would take the master cylinder off first then loosen the four bolts underneath the dash, this gives enough room to slide the stuff off the bolt. The hard part is actually taking the booster out, I removed the ECU and pulled the master cylinder forward and with a little maneuvering pulled the booster out.
It would have been easier to take remove the brake lines and take out the master cylinder, I just didn't want to buy brake fluid or have to bleed the brakes. In all it took about an hour and 1/2, but I kinda took my time. Hope that helps and good luck.
 

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2002 envoy_slt
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Discussion Starter · #3 ·
Sure do just replaced mine today! The clip is actually fairly simple, you need to take down the black plastic cover under the dash (two 7mm bolts on either side hold it up). Then find the lip of the clip and pull it down use a flat head screwdriver and lift the piece lying on top of the bolt then push the clip upwards.
I would take the master cylinder off first then loosen the four bolts underneath the dash, this gives enough room to slide the stuff off the bolt. The hard part is actually taking the booster out, I removed the ECU and pulled the master cylinder forward and with a little maneuvering pulled the booster out.
It would have been easier to take remove the brake lines and take out the master cylinder, I just didn't want to buy brake fluid or have to bleed the brakes. In all it took about an hour and 1/2, but I kinda took my time. Hope that helps and good luck.

Thank you, thank you! :thumbsup: Those are great tips, and exactly what I was looking for. I appreciate you for taking the time to post. I'm going to go give this a shot this morning.
 

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2002 envoy_slt
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Discussion Starter · #4 · (Edited)
Got the brake booster swapped, thanks again for the tips Chazr246. I really appreciate it.

Unfortunately my brake issue is not over. Instead of the mushy brake pedal I had before...The pedal is now super stiff, and you have to press down insanely hard to get the vehicle to stop. There is a hissing noise coming from the vacuum hose leading to the brake booster now. I didn't change the check valve on the hose, so I am going to do that this morning after I get the part. Hopefully that is what it is. :bonk:
 

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2004 gmc envoy_slt_xuv
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Got the brake booster swapped, thanks again for the tips Chazr246. I really appreciate it.

Unfortunately my brake issue is not over. Instead of the mushy brake pedal I had before...The pedal is now super stiff, and you have to press down insanely hard to get the vehicle to stop. There is a hissing noise coming from the vacuum hose leading to the brake booster now. I didn't change the check valve on the hose, so I am going to do that this morning after I get the part. Hopefully that is what it is. :bonk:
A mushy brake pedal is common on these Trailvoys and I haven't heard of too many Boosters going out. Usually the problem occurs when the brake system is disturbed during service. A lot of members (including myself) report that an actuation of the ABS on a dirt road improves them considerably and multiple actuations of the ABS over time has made mine almost "normal". If you can make the pedal come closer to normal by apply-release-apply then it is probably not the booster.

In the case of your new one, Either you are not getting vacuum to the booster (like you suspect) or it is defective.

If it is defective, I'd take it back and put the original back on.
 

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2002 chevy trailblazer_lt
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The symptoms your describing are the ones I had before I changed my booster. Did you use the old check valve? When I bought my brake booster it came with a new one already installed. You may want to check the hose itself for cracks while your at it.
 

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Discussion Starter · #7 · (Edited)
Who knows!

The symptoms your describing are the ones I had before I changed my booster. Did you use the old check valve? When I bought my brake booster it came with a new one already installed. You may want to check the hose itself for cracks while your at it.
Yeah before I swapped the booster is had a real mushy pedal, with a gushing noise as you press the pedal. Very difficult to brake. I ordered a used booster from eBay and put it on this past weekend. Now the pedal is super stiff and there is a hissing noise under the dash.

I did go and pick up a new check valve and grommet from the stealership. I popped that on yesterday....still same problem, didnt fix anything. I don't know what it is at this point. I checked the vacuum hose, and it seems fine. No cracks or anything. Its possible I suppose the new booster that I put on is faulty as well. :duh:

I'm taking it to my latino mechanic buddy this morning and let him check it out. At this point, I haven't a clue, and I'm blindly replacing parts that I "think" is the problem. :bonk:
 

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2006 chevy trailblazer_ls
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I ordered a used booster from eBay and put it on this past weekend. Now the pedal is super stiff and there is a hissing noise under the dash.

No cracks or anything. Its possible I suppose the new booster that I put on is faulty as well. :duh:
Does sound like you got a faulty replacement. Seems unlikely but thats exactly what happened to me with my S-10. Mine was a pull from a low mileage vehicle (too bad I didn't read that it was from a 10+yr old truck) Second time around I opted for a brand new booster from the autoparts store...wasn't risking the aggravation a second time.
 
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