Mike V

Had my C5 trans rebuild by a good shop. Trans came back and I reinstalled.
During test drive I find that I don't have 4th and the car doesn't engine brake. The computer has not set any codes. Any thoughts?

Mike V

performabuilt

iTrader: (25)

first I would look at the data stream to see if the PCM is comanding the 4th shift. When you say no engine braking do you mean in the lower gears d&3 2 1 or in the OD 4th position

Mike V

Why would the PCM not command 4th? Nothing was changed except the transmission rebuild. I mean in the 3rd or 4th position.

Thanks for the help.

Mike V

Jordan S.

iTrader: (17)

I think he's talking about when he manually shifts it into a lower gear the gears dont pull the rpm's down ?

performabuilt

iTrader: (25)

Yes I think he is speaking of d21 not OD since there is very very little engi9ne braking in the OD position since the overun clutch is not on ,

As for why wouldnt it comand the 4th shift thats hard to say but in any diagnosis of a no upshift or really any shifting issue the first thing is to look and see what the PCM is telling the trans to do.

Mike V

In third at 60 MPH you let off the throttle and the rpm's drop to <1K and the car just coasts.

Mike V

performabuilt

iTrader: (25)

If your in the OD position in 3rd gear you would have very little engine braking probably not noticable. Nowin the D position you should feel engine braking when you let off

Mike V

Fells the same in D as the trans is not shifting into 4th.

Mike V

big wally 55

At 50 to 60 mph you probably wont feel a brake effect . If you have an available scan tool you can watch data to see if it is comanding 4th gear at all . The band is on in 2cd and 4th but applied through a different circuit and a different part of the band servo . I would check the servo !!