03 Buick Century 3.1 SFI 6cyl FWD transmission, NO GEARS (POP) GET YOUR FRESH Fried Computer here



Working in the shop yesterday when my service writer Mark starts fiddling with this Buick. He wanted me to flush the trans, coolant and do an oil change. Easy stuff. He had disconnect the upper transmissions cooler line at the radiator after first removing the positive cable on the battery. We were going to use the machine to flush the transmission, then he decided to have me drop the pan, change the filter and gasket. DONE. Replaced the motor oil and filter, go to replace the cooler line then the battery terminal and ( POP!) a noise sounding as if it came from the middle of the firewall. I looked and saw nothing, nor did I smell anything. So I proceeded, hooked up the coolant flush tools and filled the transmission with oil. While filling the transmission after about 5 quarts I turn the car on and ran it through the gears, nothing. So I went to Mark and told him about it, still 2.4 quarts low. We add another quart, cars running and dipstick shows a perfect level, run it through the gears and still nothing 1.4 quarts low. We were reluctant to put the other 1.4 qaurts in since the level was showing max. I told Mark about this (POP) and he said it was normal when you replace the battery terminals. I disagreed saying replacing the positive should be attached first then the negative and that a computer could have been fried. Mark had me pull the drain pan down and replace the new filter with yet another new filter. Nothing looked disturbed, new gasket is in tack, no bends, scratches, dents, or dirt. So we start adding fluid and testing the gears and still nothing. We raise the wheels off the ground and after raising the RPM’s the wheels just barely moved. Mark suggests testing the pressure at the cooler line, so we removed the line, attached a hose he ran it in a couple (maybe all) gears and nothing came out. He is saying it is the front pump. I am saying it had to do with the (POP) Fried Computer. Anyone?


The reasoning for ‘positive; first on, last off’ is to avoid shorting it to body ground while wrenching on the terminal. The ECU doesn’t care which lead gets connected first. The battery is a very solid voltage supply so no transients will occur as the circuit is completed in either direction. That does not rule out the possibility that some strange condition caused some heavy current draw and fried a component but that’s a real longshot.

If there’s a high pressure diag port on the trans, connect a guage and see what it reads. That is, after you have the trans at the correct dipstick level with the engine idling in park. I had a hard time following the description of the fluid level you gave but the most likely suspect is that the fluid level is still low. Are you also sure that the filter pickup is firmly seated in the VB and the o-ring(s) are in place?


Yes, everything that was replaced could only fit in one way as there is little to no room for alteration. I suggested to Mark that we should then go with the book and add the remaining 1.4 quarts to make it a total of 7.4 quarts like Mitchell and the owners manual stated. This changed nothing. Our shop is closed today and tommorow when the boss comes in all hell is going to break loose(he was gone for a couple days).

We have a different opinion on this topic of the battery issue and what terminals should be attached and when. In every book that I have ever read when referencing the removal, replacement, or jumping a battery the negative is always attached last. I have read that failure to replace terminals in the proper sequence can fry a computer. If I knew he didn’t disconnect the negative I would not have even touched that car.

After I told Mark about it and he decided to pressure test the cooler lines we had to disconnect the termianl again to get to the line. This time the (POP) was not heard nor was it heard putting the negative on last. Maybe it was a freak occurance but I lean towards always attaching the negative last for reasons other then personal safety.