Test Q - Brake On/Off (Boo)
To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: brake lamp bulb, brake lamp switch, or brake lamp fuse.
- Code 74 Displayed. If brake was NOT depressed during KEY ON/ENGINE RUNNING (KOER) SELF-TEST, repeat test and depress brake pedal ONLY once during test. Depress and release brake pedal AFTER dynamic response code 1 (10 on STAR tester) but before brief WOT. If pedal was depressed, go to next step.
- Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, and loose wires. Install breakout box, leaving ECA disconnected. Set DVOM on 20 volt scale. Measure voltage between test pins No. 2 and 40 while applying and releasing brake. If voltage cycles, replace ECA and repeat QUICK TEST . If voltage does not cycle, go to next step.
- Turn key off. Leave breakout box installed and ECA disconnected. Set DVOM on 200-ohm scale. Disconnect BOO circuit at the 12-pin connector. Measure resistance between test pin No. 2 and ground. If reading is less than 5 ohms, repair BOO circuit short to ground. Repeat KOER SELF-TEST. If reading is greater than 5 ohms, proceed to step 6).
- Code 75 Displayed. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 20-volt scale. Measure voltage between test pins No. 2 and 40 while applying and releasing brake. If voltage cycles, replace ECA and repeat QUICK TEST . If voltage does not cycle, go to next step.
- Turn key off. With breakout box installed and ECA disconnected, set DVOM on 20-volt scale. Disconnect BOO circuit at 12 pin connector. Measure voltage between test pin No. 2 and engine block ground. If reading is greater than 10.5 volts, repair BOO circuit short to power. If reading is less than 10.5 volts, BOO circuit is okay. Check brake lamp circuit.
- Turn key off. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Disconnect BOO circuit at 12 pin connector. Measure resistance between test pin No. 2 and 12-pin connector. If reading is greater than 5 ohms, repair open in BOO circuit. Repeat KOER SELF-TEST. If reading is lower than 5 ohms, BOO circuit is okay. Check brake lamp circuit.