So i have a '94 C1500 that i just finished swapping the transmission(4L60E) in. Before the swap the brakes felt awesome. Barely a touch was enough to stop the truck. Well after the swap i took it for a test drive around the block and the brakes were very weak. Like I had to push almost as hard as I could on the pedal to even slow down.

Any ideas what could cause this??? The brake fluid resevior is full and I didnt touch the brakes during the swap. Could a bad electrical connection to the tranny cause this? could leaving the battery disconnected over the weekend have cleared something in the computer memory or something??

Sorry I am new to DIY vehicle stuff and only owned a chevy for like a week. lol Thx all for the help!!

 

Sound like the brake booster which the master cylinder is connected to is not getting the vacumn necessary for the unit to work.. Look to see if you accidentally disconnected the vacumn line or even broke the fitting which is usually plastic. As for the tranny causing the problem (No) As for the disconnect of battery it may cause the ABS to mess up but should correct itself after a few starts. That is if your truck has ABS. Just some suggestions/

 

+1 for checking the booster

will the truck off...step on the brake repeatedly to deplete the vacuum reserve in the booster. Push and hold the brake pedal down...start the truck...the pedal should move down more if the booster is good.

if this check fails, check the vacuum supply to the booster.

 

Hey guys thx both for the replies. Looks like it was the abs computer. After letting it sit overnight with the battery connected the brakes worked fine in the morning. I never knew that a computer reset could affect the brakes. But then again if I had a nickle for everything I didn't know about cars then I would have a lot of nickles. So glad I don't have to learn about brakes right now after just finishing learning how to replace a tranny lol. Thx again for the replies.