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:
- Communication harness circuit (ISO)
- Harness circuits (GND, VPWR)
- Faulty PCM.
CIRCUIT PIN IDENTIFICATION
| Circuit | Breakout Box Pin No. | PCM Pin | Wire Color |
|---|---|---|---|
| ISO | 20 | C1-7 | Red/Orange |
| GND | 90 | C4-31 | Black |
| GND | 93 | C4-32 | Black |
| GND | 96 | C4-33 | Black |
| GND | 99 | C4-34 | Black |
- 1) Verify Self-Test Procedure Is Correct Check OBD-II DLC for damage. Ensure scan tool is correctly plugged into DLC, located under instrument panel. DO NOT use diagnostic connector located in engine compartment. Ensure correct self-test procedure is used. Repeat procedure if necessary. If correct procedure was used, go to next step.
- 2) Check For VREF At TP Sensor
Turn ignition off. Disconnect TP sensor. Turn ignition on. Measure voltage between SIG RTN terminal and VREF terminal at TP wiring harness connector. See Figure. If voltage is 4-6 volts, reconnect TP sensor and go to next step. If voltage is not 4-6 volts, reconnect TP sensor and go to CIRCUIT TEST C.NOTE: KOER self-test failure or Communication Error message could result if a failure is present in MAF sensor, MLP sensor, VSS or related circuits.
- 3) Check Ground At OBD-II DLC Turn ignition off. Inspect OBD-II DLC for damage. Measure resistance between pin No. 4 (ground) at OBD-II DLC and chassis ground on engine block. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open ground circuit. Repeat QUICK TEST .
- 4) Check Power At OBD-II DLC Turn ignition off. Measure voltage between pin No. 16 and pin No. 4 at OBD-II DLC. If voltage is greater than 10 volts, go to next step. If voltage is less than 10 volts, repair open B+ circuit. Repeat QUICK TEST .
- 5) Check Ground At OBD-II DLC Turn ignition off. Install breakout box (leave PCM disconnected). Measure resistance between pin No. 5 at OBD-II DLC and breakout box test pin GND. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open GND circuit. Repeat QUICK TEST .
- 6) Check ISO Circuit Continuity Turn ignition off. Install breakout box (leave PCM disconnected). Measure resistance between pin No. 7 at OBD-II DLC and breakout box test pin ISO. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open ISO circuit. Remove breakout box and repeat QUICK TEST .
- 7) Check ISO Circuit For Short To Ground Turn ignition off. Install breakout box (leave PCM disconnected). Measure resistance between pin No. 7 at OBD-II DLC and ground. If resistance is greater than 10,000 ohms, go to next step. If resistance is less than 10,000 ohms, repair shorted ISO circuit. Remove breakout box and repeat QUICK TEST .
- 8) Check ISO Circuit For Short To Power Turn ignition off. Install breakout box (leave PCM disconnected). Turn ignition on. Measure voltage between breakout box test pin ISO and test pin GND. If voltage is less than one volt, replace PCM. Remove breakout box and repeat QUICK TEST . If voltage is greater than one volt, repair short to voltage in ISO circuit. Remove breakout box and repeat QUICK TEST .