Diagnostic Aids
WARNING: This page is about a different variant/trim than selected.
Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used to diagnose the following:
- Wiring harness circuits (TCIL and TCS).
- Faulty Powertrain Control Module (PCM).
- 1) DTC P1780
This DTC indicates Transmission Control Switch (TCS) was not cycled during KOER self-test. Possible causes are:- Faulty TCS.
- TCS not cycled during self-test.
- Open or short in wiring harness.
- Faulty PCM.
Turn ignition off. Connect scan tool to Data Link Connector (DLC). Start engine and allow to idle. Using scan tool, select TCS PID. Cycle TCS switch, then hold depressed. If PID value indicates ON, go to next step. If PID value indicates OFF, repeat KOER ON-DEMAND SELF-TEST to cycle TCS.
- 2) Check TCS Circuit Voltage
Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Turn ignition on. Measure voltage between test pin No. 29 (TCS) and test pins No. 24 and 77 (PWR GND) at breakout box while cycling TCS. If voltage reading does not cycle when TCS is cycled, go to next step. If voltage reading cycles when TCS is cycled, replace PCM and repeat QUICK TEST . - 3) Check Circuit For Short To Ground
Turn ignition off. Disconnect TCS. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Measure resistance between test pin No. 29 (TCS) and test pins No. 24 and 77 (PWR GND) at breakout box. If both resistance readings are 10,000 ohms or more, go to next step. If any resistance reading is 10,000 ohms or less, repair short to ground in TCS circuit. - 4) Check Continuity Of TCS Circuits
Connect ohmmeter positive lead to TCS key power at the fuse panel. Connect negative lead to power terminal at TCS wiring harness connector. Note resistance reading. Measure resistance between test pin No. 29 (TCS) at breakout box and TCS terminal at TCS wiring harness connector. If both resistance readings are less than 5 ohms, go to next step. If any resistance reading is 5 ohms or more, repair open TCS circuit. - 5) Check Circuit For Short To Power
Measure resistance between test pin No. 29 (TCS) and test pins No. 71 and 97 (VPWR) at breakout box. If both resistance readings are more than 10,000 ohms, replace TCS. If any resistance reading is 10,000 ohms or less, repair short to power in TCS circuit. - 6) Check TCIL PID
Using scan tool, select TCIL PID. Cycle TCS. If PID value changes from ON to OFF, fault is intermittent. Go to CIRCUIT TEST Z . If PID value does not change from ON to OFF, go to next step. - 7) Check For Short to Ground In TCIL Circuit
Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Turn ignition on. If TCIL turns off, replace PCM. If TCIL remains on, repair short to ground in TCIL circuit. - 8) Check For DTC P1780
Perform KOER ON-DEMAND SELF-TEST . If DTC P1780 is not present, go to next step. If DTC P1780 is present, go to step 1). - 9) Check Voltage To TCIL
Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Turn ignition on. Measure voltage between TCIL test pin and test pins No. 24 and 76 (PWR GND) at breakout box. See Fig 1. If both voltage reading are more than 2 volts, replace PCM. If any voltage reading is 2 volts or less, check indicator bulb and fuse. Repair as necessary. If bulb and fuse are okay, repair open in circuit between test pin No. 79 and ignition switch.