Hello all, I have a D4 flashing and a code 9 on my TCU. Code 9 is a counter shaft speed sensor error. I have checked the sensor and wiring from sensor to TCU, all checks good. I have swapped TCUs and get the same code. Any suggestions welcome. Thank you.

 

What year and model car?

How did you check the sensor and wiring? Did you only visually check or used a multi-meter?

 

Might want to pull the sensor and verify it is not covered in a ferrous slurry. That will affect signal resolution.

 

92 ex 2.2 F22A6. I used a meter to check wiring and sensor. Replaced the sensor and still get the code. Shifts into lockup and about 5 seconds it shifts back out of lock up and flashes a code 9. Once it has flashed, its done until I shut off the car and restart. Then same thing again. The lock up solenoids are both working and tested. Thanks

 

Verify none of the connections have loose, damaged, or corroded pins.
Verify your engine harness ground on the thermostat housing is not loose, damaged, or corroded.
Verify your main ground at the trans and bonding jumper on the engine mount is not missing, loose, damaged, or corroded.

 

You indicated you swapped the TCU/TCM; but, still the Code 9 persist. Open up and take a look at the ECM; capacitors do go bad after so many years.

There are various signals that go through between the ECM and TCM. The issue may possibly be on the ECM side.

 

Found the problem! Was a short in the two wire, shielded cable to the counter shaft sensor. Thanks for all the suggestions and help.