On Board Diagnostics II PCED

1999 PCED On Board Diagnostics II

SECTION 5: Pinpoint Tests

TB: Transmission Control Switch (TCS)/Transmission Control Indicator Lamp (TCIL)

DTC P1780

Did TCS PID reading switch from ON to OFF, and did reading indicate ON when button was depressed?

Yes	No
RERUN KOER Self-Test to cycle TCS.	GO to TB2 .

Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Disconnect PCM.
Key on, engine off.
Measure the voltage between the PCM harness connector pin and battery negative post while cycling the TCS several times.
Key off.

Did the voltage cycle?

Yes	No
REPLACE PCM (refer to Section 2 , Flash EEPROM).	GO to TB3 .

Disconnect TCS.
Measure the resistance between PCM harness connector pin and battery negative post.

Is resistance greater than 10,000 ohms?

Yes	No
GO to TB4 .	REPAIR short circuit.

Measure the resistance of the TCS keypower between fuse junction panel and power side of the TCS harness connector.
Measure resistance of TCS circuit between PCM harness connector pin and the transmission control switch harness connector.

Are both resistances less than 5.0 ohms?

Yes	No
GO to TB5 .	REPAIR open circuit.

Measure the resistance between TCS and VPWR circuits at the PCM harness connector.

Is resistance greater than 10,000 ohms?

Yes	No
REPLACE damaged transmission control switch.	REPAIR short circuit.

Did the TCIL lamp change state?

Yes	No
GO to Pinpoint Test Step Z1 to check for an intermittent fault .	GO to TB7 .

Did the TCIL lamp change state?

Yes	No
TCIL turns off when PCM is disconnected. REPLACE PCM (refer to Section 2 , Flash EEPROM).	REPAIR short circuit between bulb and the TCIL Test Pin. VERIFY a symptom no longer exists.

Is DTC P1780 present?

Yes	No
REPAIR DTC 1780. GO to TB1 .	GO to TB9 .

Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Key off.
Disconnect PCM.
Key on, engine off.
Measure voltage between TCIL PCM harness connector pin and battery negative post.

Are voltage readings greater than 2.0 volts?

Yes	No
REPLACE PCM (refer to Section 2 , Flash EEPROM). CYCLE TCS to check operation of TCIL.	CHECK indicator bulb and fuse. If OK, open is in the wiring between the Ignition switch and the TCIL Test Pin at the harness connector. REPAIR as necessary.