Pinpoint Test B
Enter this pinpoint test only when service Codes 74 or 75 are received in the KEY ON, ENGINE OFF SELF-TEST. To prevent replacement of good components, the brake light, brake switch and/or fuses (non-IVSC areas) might be at fault. This pinpoint test is intended to diagnose the BOO circuit and the ECA.
- Service Code 74 has appeared. If brake is pressed during KEY ON, ENGINE OFF SELF-TEST, go to Step 2). If not, perform KEY ON, ENGINE OFF SELF-TEST and press brake once during test.
- Turn key off and wait 10 seconds. Disconnect ECA 60-Pin connector. Inspect for damage. Service as necessary. Install Breakout box, leaving ECA disconnected. Set DVOM on 20-volt scale. Measure voltage between test pin 2 and test pin 40 at Breakout box while depressing and releasing brake. If voltage cycles, replace ECA and retest. If not, go to step 3).
- Turn key off. Install Breakout box. Disconnect ECA. Set DVOM on 200-ohm scale. Disconnect BOO circuit from 14290 harness (12-pin connector). Measure resistance between test pin 2 at Breakout box and ground. If resistance reading is greater than 5 ohms, service stop light circuit. If not, service BOO circuit short to ground.
- Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for damage. Service as necessary. Install Breakout box, leaving ECA disconnected. Set DVOM on 20-volt scale. Measure voltage between test pin 2 and test pin 40 at Breakout box while depressing and releasing brake. If voltage cycles, replace ECA and perform QUICK TEST. If not, go to Step 5).
- Turn key off. Install Breakout box. Disconnect ECA. Set DVOM on 20-volt scale. Disconnect BOO circuit from 14290 harness (12-pin connector). Measure voltage between test pin 2 at Breakout box and engine block ground. If voltage reading is greater than 10.5 volts, service BOO circuit short-to-power. If not, BOO circuit is okay. Service stop light circuit. See Fig 1.