DTC 121

EAE. Code 1-2-1

1-2-1 Short-circuit to ground in solenoid S1 circuit

DTC information


Conditions for DTC






Solenoid S1 works together with solenoid S2 and controls transmission gear-shifting. Solenoid S1 operates when battery voltage is applied from the transmission control module (TCM) and is activated in 2nd and 3rd gears. If the TCM registers a short-circuit to ground on the solenoid S1 circuit when the solenoid should be activated DTC 1-2-1 is set. Solenoid S1 cannot then be activated.

Substitution value

The TCM "Limp-home" program has been initiated and the transmission operates only in 4th gear.

Defect Cause

- Short circuit to ground in the signal wiring.
- Malfunction in solenoid

Fault symptom

- Poor performance due to the transmission starting in 3rd or 4th gear.
- Fault-tracing starts with EAE1.


EAE1

Checking Solenoid S1






- Ignition ON.
- Set gearshift selector to position P.

Check solenoid S1 using Diagnostic Test Mode 4. Use a stethoscope to hear if the solenoid is operating.

If solenoid is operating:
- Intermittent fault. Fault-tracing as per EAE4.

If the solenoid is not opening:
- Check signal wiring resistance to ground in the transmission EAE2.



EAE2

Check signal wiring resistance to ground in the transmission






- Ignition OFF
- Remove the air cleaner (AC) housing to access the transmission connector
- Disconnect the transmission connector

Connect an ohmmeter between the transmission connector terminal 21 (transmission side) and the transmission housing.

The ohmmeter should read 1O-15 Ohms.

If reading is OK:
- Check the cable between the transmission connector terminal 21 and the TCM #A27 for short circuit to ground as per FA3. FA. Checking Wiring and Connections

If reading is incorrect
- Check solenoid S1 EAE3.


EAE3

Checking solenoid S1






- Ignition OFF
- Open the control system, as per R1-R13.
- Disconnect solenoid S1.

Use an ohmmeter to measure between the pin on solenoid S1 and the transmission housing.
The ohmmeter should read approx. 10-15 Ohms.

If reading is OK:
- Check the cable between the transmission connector terminal 21 and solenoid S1 for short circuit to ground as per FA3. FA. Checking Wiring and Connections

If replacing cable harness, refer to R49-R57.

If reading is incorrect:
- Try a new solenoid S1 as per R20.

EAE4

Intermittent fault.

Checking wiring and connections






- Check the wiring between solenoid S1 in the transmission and TCM #A27 for intermittent short circuit to ground as per FA3. FA. Checking Wiring and Connections