Test O - Brake On/Off (Boo) Switch
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 pressed during ENGINE RUNNING SELF-TEST, repeat test and press brake pedal once during test. If pedal was pressed, go to next step.
- 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 pin 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 with ECA disconnected. Set DVOM on 200-ohm scale. Disconnect BOO circuit at 12 pin connector. Measure resistance between test pin 2 and ground. If reading is less than 5 ohms, repair BOO circuit short to ground. If reading is greater than 5 ohms, BOO circuit is okay. Check brake lamp circuit.
- 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 pin 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 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.