TCM Self-Diagnosis Does Not Activate
21. TCM Self-diagnosis Does Not Activate (PNP, Overdrive Control and Throttle Position Switches Circuit Checks)SYMPTOM: O/D OFF indicator lamp does not come on in TCM self-diagnostic procedure even the lamp circuit is good.
DESCRIPTION
PNP Switch
The PNP switch assembly includes a transmission range switch. The transmission range switch detects the selector position and sends a signal to the TCM.
Overdrive Control Switch
Detects the overdrive control switch position (ON or OFF) and sends a signal to the TCM.
Throttle Position Switch
Consists of a wide open throttle position switch and a closed throttle position switch.
The wide open position switch sends a signal to the TCM when the throttle valve is open at least 1/2 of the full throttle position. The closed throttle position switch sends a signal to the TCM when the throttle valve is fully closed.
DIAGNOSTIC PROCEDURE
NOTE: The diagnostic procedure includes inspections for the overdrive control and throttle position switch circuits.
1. CHECK PNP SWITCH CIRCUIT (WITH CONSULT-II)
With CONSULT-II
1. Turn ignition switch to ON position.
(Do not start engine.)
2. Select "TCM INPUT SIGNALS" in "DATA MONITOR" mode for "A/T" with CONSULT-II.
3. Read out P, R, N, D, 2 and 1 position switches moving selector lever to each position. Check the signal of the selector lever position is indicated properly.
OK or NG?
OK >> GO TO 3.
NG >> Check the following items:
- PNP switch
- Harness for short or open between ignition switch and PNP switch (Main harness)
- Harness for short or open between PNP switch and TCM (Main harness)
2. CHECK PNP SWITCH CIRCUIT (WITHOUT CONSULT-II)
Without CONSULT-II
1. Turn ignition switch to ON position.
(Do not start engine.)
2. Check voltage between TCM harness connector M78 terminals (26, 27, 34, 35, 36) and ground while moving selector lever through each position.
Does battery voltage exist (B) or non-existent (0)?
Yes >> GO TO 3.
No >> Check the following items:
- PNP switch
- Harness for short or open between ignition switch and PNP switch (Main harness)
- Harness for short or open between PNP switch and TCM (Main harness)
3. CHECK OVERDRIVE CONTROL SWITCH CIRCUIT
With CONSULT-II
1. Turn ignition switch to ON position.
(Do not start engine.)
2. Select "TCM INPUT SIGNALS" in "DATA MONITOR" mode for "A/T" with CONSULT-II.
3. Read out "OVERDRIVE SWITCH". Check the signal of the overdrive control switch is indicated properly.
(Overdrive control switch ON displayed on CONSULT-II means overdrive OFF.)
Without CONSULT-II
1. Turn ignition switch to ON position.
(Do not start engine.)
2. Check voltage between TCM terminal 22 and ground when overdrive control switch is ON and OFF.
Voltage:
Switch position ON .... Battery voltage.
Switch position OFF .... 1V or less.
OK or NG?
OK (With CONSULT-II) >> GO TO 4
OK (Without CONSULT-II) >> GO TO 5
NG >> Check the following items:
- Overdrive control switch
- Harness for short or open between TCM and overdrive control switch (Main harness)
- Harness for short or open of ground circuit for overdrive control switch (Main harness)
4. CHECK THROTTLE POSITION SWITCH CIRCUIT (WITH CONSULT-II)
With CONSULT-II
1. Turn ignition switch to ON position.
(Do not start engine.)
2. Select "TCM INPUT SIGNALS" in "DATA MONITOR" mode for "A/T" with CONSULT-II.
3. Read out "CLOSED THL/SW" and "W/O THRL/P-SW" depressing and releasing accelerator pedal.
Check the signal of throttle position switch is indicated properly.
OK or NG?
OK >> GO TO 6.
NG >> Check the following items:
- Throttle position switch
- Harness for short or open between ignition switch and throttle position switch (Main harness)
- Harness for short or open between throttle position switch and TCM (Main harness)
5. CHECK THROTTLE POSITION SWITCH CIRCUIT (WITHOUT CONSULT-II)
Without CONSULT-II
1. Turn ignition switch to ON position.
(Do not start engine.)
2. Check voltage between TCM terminals 16 (BR/W), 17 (OR/B) and ground while depressing, and releasing accelerator pedal slowly. (after warming up engine)
OK or NG?
OK >> GO TO 6.
NG >> Check the following items:
- Throttle position switch
- Harness for short or open between ignition switch and throttle position switch (Main harness)
- Harness for short or open between throttle position switch and TCM (Main harness)
6. CHECK DTC
Perform "DIAGNOSTIC PROCEDURE".
OK or NG?
OK >> INSPECTION END.
NG >>
1. Perform TCM input/output signal inspection Pinout Values and Diagnostic Parameters.
2. If NG, recheck TCM pin terminals for damage or loose connection with harness connector.
COMPONENT INSPECTION
Overdrive Control Switch
Check continuity between terminals 5 and 6.
Continuity:
Switch position ON: ....... No
Switch position OFF: ...... Yes
PNP Switch
1. Check continuity between terminals 1 and 2 and between terminals 3 and (4, 5, 6, 7, 8, 9) while moving manual shaft through each position.
2. If NG, check again with manual control linkage disconnected from manual shaft of A/T assembly. Refer to step 1.
3. If OK on step 2, adjust manual control linkage.
4. If NG on step 2, remove PNP switch from A/T and check continuity of PNP switch terminals. Refer to step 1.
5. If OK on step 4, adjust PNP switch. Refer to "Park/Neutral Position (PNP) Switch Adjustment".
6. If NG on step 4, replace PNP switch.
Throttle Position Switch
Closed Throttle Position Switch (Idle Position)
Check continuity between terminals 4 and 5.
To adjust closed throttle position switch, refer to "Basic Inspection".
Wide Open Throttle Position Switch
Check continuity between terminals 5 and 6.