MarauderZ28

Hello, I have a problem with my 4L60-E tranny. I changed the valve body due to the error code P1870. I bought a remanufactured valve body from Sonnax. At the same time, I installed Sonnax Pinless Accumulator kit for forward accumulator and for 3-4 gear accumulators. After set, it worked good, gearbox shifted smoothly, much better than before. But the first gear does not work at all, tranny behaves as if it doesn't have any first gear. Having the car started, it drives directly in the second gear, even if I manually set the first gear. Gearbox doesn't emit any wrong tone. Any ideas, what can be the cause? Fuse, check ball on the wrong place, faulty solenoid, I don't have any clue what to look for. Not even a check engine light on or any code…

Car - Impala SS, 96 ...

Performabuilt

Do you have 2-3-4 ? or just 2 and 3 ?

MarauderZ28

I have the second, third and fourth gear as well. Only first gear is missing.

Performabuilt

Thats strange and it means all the solenoidsare working , The problem could be with the 1-2 accumulator missing or broken seals or oring this can cause second gear starts .

MarauderZ28

Advice from Sonnax:

Hello Jiri
I am assuming you did not have the transmission out but just did the Valve Body and accumulators with the unit still installed.
I will give you several ideas of where to look but if you did have the unit out, check for pinched wiring as well.

Even thought there is no check engine light yet, put a scan tool on it and check for codes or pending codes.
Also be sure to monitor your pressure switch signals. Codes or an inappropriate pressure switch state might lead you to the problem area.

A few known causes for 2nd gear starts, even if manual low selected but all other gears normal:

PSA circuit not connected
Code 24,72,81 or 82
Voltage pulls down to low during starting
Stuck 1-2 shift valve. Also if you go into the valvebody, inspect the AFL valve. It can also cause wrong gear starts.
Spacer plate holes plugged or blocked spacer plate holes due to mismatched plate
Blocked solenoid feeds.

I hope this helps. Good luck