Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Test Procedure
2003 Jaguar XK8 2D CoupeSECTION Diagnostic Test Procedure
- Disconnect negative battery cable. Disconnect the TPS connector. Disconnect ECM connector EM81. Measure resistance between TPS connector terminal No. 3 and ECM harness connector EM81 terminal No. 10. Is resistance greater than 5 ohms? If yes, repair high resistance between TPS connector terminal No. 3 and ECM harness connector EM81 terminal No. 10. If no, go to next step.
- Reconnect negative battery cable. Remove the throttle motor power relay. Measure voltage between the throttle motor power relay connector terminal No. 3 and ground. Is voltage greater than 10 volts? If yes, go to next step. If no, repair circuit between the throttle motor power relay connector terminal No. 3 and the battery. This circuit includes the EMS fuse box (fuse No. 9).
- Turn ignition on. Measure voltage between the throttle motor power relay connector terminal No. 1 and ground. Is voltage greater than 10 volts? If yes, go to next step. If no, repair circuit between the throttle motor power relay connector terminal No. 1 and the battery. This circuit includes the EMS fuse box (fuse No. 14) and the EMS control relay.
- Disconnect negative battery cable. Disconnect ECM connector EM82. Measure resistance between ECM harness connector EM82 terminal No. 6 and throttle motor power relay connector terminal No. 2. Is resistance greater than 5 ohms? If yes, repair high resistance between ECM harness connector EM82 terminal No. 6 and throttle motor power relay connector terminal No. 2. If no, go to next step.
- Reconnect ECM connector EM82. Disconnect ECM connector EM80. Install the throttle motor power relay. Reconnect negative battery cable. Turn ignition on. Measure voltage between ground and ECM harness connector EM80 terminals No. 8 and 9. Is voltage greater than 10 volts? If yes, go to next step. If no, install a new throttle motor power relay.
- Disconnect the throttle motor connector. Measure resistance between throttle motor harness connector terminal No. 1 and ECM harness connector EM80 terminals No. 6 and 7. Are either resistance greater than 5 ohms? If yes, repair high resistance between throttle motor harness connector terminal No. 1 and ECM harness connector EM80 terminals No. 6 and 7. If no, go to next step.
- Measure resistance between throttle motor harness connector terminal No. 2 and ECM harness connector EM80 terminals No. 4 and 5. Are either resistance greater than 5 ohms? If yes, repair high resistance between throttle motor harness connector terminal No. 2 and ECM harness connector EM80 terminals No. 4 and 5. If no, go to next step.
- Reconnect ECM connector EM80. Turn ignition on. Measure voltage between throttle motor harness connector terminal No.1 and ground. Is voltage greater than 10 volts, repair short to voltage. If no, go to next step.
- Disconnect ECM connector EM80. Turn ignition off. Measure resistance between throttle motor harness connector terminal No. 1 and ground. Is resistance less than 10,000 ohms? If yes, repair short to ground. If no, install a new throttle body.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.