TCU Error codes are indicated by the “S” light on 90-91 models, and the “D4″ light on 92-93 models. The codes can be read in the same way, with paperclip method, as the ECU codes, by counting the flashes of these lights.
1. If your check engine light is on, start by going to your passenger side kickpanel.
There should be a blue connector w/2 wires to it. Put a paper clip or piece of wire in to the connector to connect the two prongs.
2. Put the key in the ignition, and turn the key 2 clicks to the acc on, where all the lights light up on the dash.
3. You will now watch how many times the S/D4 light blinks.
a long blink = 10
a short blink = 1
It will repeat after all the codes are done.
4. Compare to this list to see what the problem is:
0-Transmission control unit (TCU) faulty.
1-Lock-up solenoid ‘A’ circuit open or shorted.
2-Lock-up solenoid ‘B’ circuit open or shorted.
3-Throttle Position Sensor circuit open or shorted.
4-Vehicle Speed Sensor open or shorted – No signal from speedometer.
5-Shift Lever Position Switch circuit shorted.
6-Shift Lever Position Switch circuit open.
7-Shift Solenoid ‘A’ circuit open or shorted.
8-Shift Solenoid ‘B’ circuit open or shorted.
9-Counter shaft or transmission speed pulse generator open or shorted.
10-Coolant Temperature Sensor open or shorted.
11-Engine RPM (Ignition coil signal) open or shorted.
12-(No code 12 used)
13-Main shaft speed pulse generator open or shorted.
14-Linear (line pressure control) solenoid open or shorted.
15-Kick down switch circuit shorted.
Post time: Aug-30-2018