2003 tls 289,000 miles.


On Friday the engine light came on along with the vsa and triangle. I pulled the codes: P0300, P0302, P0304, P0305, P1399, and P1740. All codes except the last one are misfire codes. The P1740 is a code for: 4th pressure switch failure. The transmission in the car is not the original one. It was replaced at around 90,000 miles. I bought the car from a friend and have the service records showing it was replaced (not an oil jet kit add-on). The transmission fluid is fine, the car has never had any shifting issues. I replaced the switch this morning but haven't cleared the code(s) yet. I drove the car and within a few 100' the lights came on. The engine light will stay on while driving until I press the accelerator (not hard at all, but steady) and then the light starts flashing. Once I let off of the accelerator, the light goes back to constantly on. Once again, if I press the gas it starts flashing again. The engine seems to be rough (shake) under acceleration and above 40 or so mph.


Any suggestions? I purchased a new coil and plan on testing that next. Are the misfire codes and the transmission code a related issue?

 

Try to resolve the "misfire" conditions first. Maybe just a bad coil.
Is the "D-5" indicator flashing also ?

The P1740 may be a wiring problem or faulty 4th gear pressure switch.
Check for a short to ground, poor connection or open wire to PCM.

 

sounds like a coil at least- do the power lead connector to coil removal and see if engine rpm drops- if not its the bad coil!
reset ecu the easy way to clear codes= open passenger front door- remove access panel on end of dash- remove CLOCK fuse for a minute and reinsert- no kidding
its the secret ecu backup power
must be done after coil swaps or install of new coil

ck the spark plug at the bad coil for crud buildup