: trans code

01-30-05, 10:29 AM
can anyone shed some light on the code po56? what does it mean,how to correct it and does it affect thr driveabilty of the car?how major or minor is this code.the car is a 95 sls with 116,000 on the clock

01-30-05, 01:36 PM
Test conditions

1. Codes p024, p075, and p091 NOT set
2. Trans not in neutral or park
3. engine running.
4. vehicle speed greater than 10 MPH

Failure condition

1. Input shaft speed 50 RPM or less for 2 seconds.

Action taken

1. Turn on SES lamp
2. PCM calculates input speed based on output speed and gear ratio.
3. PCM calculates slip speed using calculated input speed.
4. TCC engaged
5. garage shift adapts frozen at current level
6. shift adapts frozen at current level
7. Torque management disabled.



01-30-05, 01:46 PM
To diagnose

WIth engine running and trans in park check PD72

If greater than 100 rpm the fault is not present check for EMI sources near wiring and wait for fault to reappear

If less than 100 RPM then turn engine off and disconnect trans connector. Measure frequency between a and b pins on trans with engine running and in park.

0 hz then check wiring in trans. If no problems found then replace inupt sensor.

Not 0 hz then turn engine of and reconnect connector. Back probe terminals 1b3 and 1b4 at PCM

0 hz then repair wiring between trans and pcm.

not 0 hz then inspect terminals 1b3 and 1b4. If ok then replace PCM.

The sensor was a common failure point and a good bet if you can't perform the diagnosistic.