Brake pressure light

[jfbushee]

Have resently had a problem with my 4L80E tranny. Was wondering if this could be a result of a brake issue? The light comes on at 35 Mph and the tranny does not shift seems like it stays in second or some other gear. When I stop and restart it stays out until 35 Mph. Replaced rear brakes and left wheel cylinder at the same time everything bleed out ok this was done a week before everything else happened. I have replaced the input and output sensors on tranny,shifting solenoids both A&B, Vehicle Speed sensor on tranfer case, TCC solenoid, TPS. This alll seemed to happen about the same time the IP went south since then the pump was replaced but still have this issue with then tranny could someone please help me.:confused:

[JohnC]

What codes are set?

Monitor the voltage on the trans circuit. If it drops below about 9 volts while the PCM is either testing or activating one of the solenoids it'll do what you describe.

Or, it could be mechanical...

[jfbushee]

It shows no codes at all.

[JohnC]

What light is it that's coming on? I assumed you meant the check engine light. If so, there should be a code. If the trans won't shift and doesn't set a code that tells me that for some reason it doesn't think it's supposed to shift. This could be mechanical. If you put a scanner on it you can see what's going on when you think it should shift but doesn't.

I notice you say there was a pump replacement. It could be that the TPS switch was never adjusted correctly, or was damaged in the process.

[jfbushee]

The brake pressure light comes on at 35 mph. I can not get any codes what so ever scrathing head at this point.

[JohnC]

Is the TPS plugged into the brake warning circuit?