ok my started to shift hard no cel so go to check for codes so find

0504

Diagnostic Trouble Code 0504 points to a problem with the Automatic Transmission Communications line. Pulse signals are exchanged between the Engine Control Module and the Transmission Control Module to assure smooth shifting during hard acceleration or deceleration.

This malfunction is detected when the ECM continuously receives an incorrect voltage from the TCM. Possible causes include...
- Harness or connectors (The communications line circuit between the ECM and the TCM is open or shorted.)
- TCM
- Discharged or faulty battery

how bad is that and how can i fix it i hope is not my trainy plz some one help

 

I have the same problem. i have searched everywhere, but find lttle info on this problem code. as soon as i get some repair specifics im posting asap.

 

Try this link -

http://www.automd.com/answers/check-...e-0504_q21637/

 

so why is it saying 0504 is a brake switch problem when the haynes manual says a/t control blah, blah ,blah. what gives?

 

P0504 is a brake switch problem in the form of an OBDII code. Not the same as a DTC code of 0504 they do not interchange that way

 

So I may have grossly misunderstood this - is the 0504 from counting the blinking light or from an OBD II reader?

 

im guess this is a tranny code. Prolly need to replace drop resistor