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Diagnostic Aids

Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used to diagnose the following:

Fig 1: TCIL & TCS Circuit Schematic
G96I29171
  1. 1) DTC P1780  Turn ignition off. Connect scan tester to Data Link Connector (DLC). Start engine and allow to idle. Using scan tester, access TCS PID. Cycle TCS switch, then hold depressed. If TCS PID is on, go to next step. If TCS PID is off, repeat KOER self-test to cycle TCS.
  2. 2) Check TCS Circuit Voltage  Turn ignition off. Disconnect PCM 104-pin connector. Inspect pins for damage. Install EEC-V 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 voltmeter reading does not cycle when TCS is cycled, go to next step. If voltmeter reading cycles when TCS is cycled, replace PCM and repeat QUICK TEST.
  3. 3) Check Circuit For Short To Ground  Turn ignition off. Disconnect TCS. Inspect pins for damage and repair if necessary. Measure resistance between breakout box test pin No. 29 (TCS) and test pins No. 24 and 77 (PWR GND). If resistance is 10,000 ohms or more, go to next step. If resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST.
  4. 4) Check Continuity Of TCS Circuits  Leave ignition off. Connect ohmmeter positive lead to TCS key power at the fuse panel. Connect negative lead to power terminal of TCS wiring harness connector. Note resistance measurement. Measure resistance between breakout box test pin No. 29 (TCS) and TCS terminal of TCS connector. If both resistance measurements are less than 5 ohms, go to next step. If either resistance measurement is 5 ohms or more, repair open circuit and repeat QUICK TEST.
  5. 5) Check Circuit For Short To Power  Leave ignition off. Measure resistance between breakout box test pin No. 29 (TCS) and test pins No. 71 and 97 (VPWR). If resistance is 10,000 ohms or more, replace TCS switch and repeat QUICK TEST. If resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST.
  6. 6) Check TCIL PID  Turn ignition off. With scan tester connected to Data Link Connector (DLC), access TCIL PID. Cycle TCS switch. If TCIL PID changes from ON to OFF, fault is intermittent. Go to CIRCUIT TEST Z . If TCIL PID does not change as specified, go to next step.
  7. 7) Check For Short to Ground In TCIL Circuit  Turn ignition off. Disconnect PCM 104-pin connector. Inspect pins for damage and repair if necessary. Turn ignition on. If TCIL goes off, replace PCM. If TCIL remains on, repair TCIL circuit short to ground.
  8. 8) Check For DTC P1780  Perform KOER self-test. If DTC P1780 is not present, go to next step. If DTC P1780 is present, go to step 1).
  9. 9) Turn ignition on. Measure voltage between TCIL test pin and test pins No. 24 and 76 (PWR GND) at breakout box. If voltage is 2 volts or more, replace PCM. If voltage is less than 2 volts, check indicator bulb and fuse. If bulb and fuse are okay, repair open circuit between test pin No. 79 and ignition switch.
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