Introduction

INTRODUCTION

TROUBLESHOOTING TECHNIQUE The following five —step troubleshooting procedure is recommended. (1) Verify the Problem oo Check the operation of the circuit to be sure you understand the problem. Do not begin disassembly or testing until you have narrowed down the possible causes. (2) Analyze the Circuit Diagram (schematic) Analyze the diagram. Check circuits that share the wiring with the problem circuit. The names of shared circuits are often given on each Circuit Diagram to aid troubleshooting. Shared power and ground circuits can be found in the Power and Ground Distribution sections. Try to operate the shared circuits. If these circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.

Find the Cause

Narrow down the possible causes. Before you replace a component, check power, signal, and ground wires at the component harness connector.

Repair the Problem

Once the specific problem is identified, make the repair. Be sure to use the correct tools and safe procedures.

(5) Check the Repair

Check the operation of the repaired circuit in all modes to make sure you fixed the entire problem. If the problem was a blown fuse, be sure to test all of the circuits on that fuse. Make sure no new problems are present.

TEST EQUIPMENT

Where applicable, Land Rover recommended testers should be used.

Voltmeter and Test Light

Use a voltmeter or test light to check for voltage. While a test light shows whether or not voltage is present, a voltmeter indicates how much voltage there is.

CAUTION: A number of circuits include solid—state devices. Voltages in these circuits should be tested only with a 10—megohm or higher impedance

digital multimeter. Never use a test light on circuits that contain solid—state devices. Damage to the device may resui. On circuits without solid —state devices, a test light may be used to check for voltage. A test light is made up of a 12—volt bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. The bulb will come on if the voltage at the point being tested is greater than 5 volts.

Self—powered Test Light and Ohmmeter Use a self—powered test light or ohmmeter to check for continuity. The ohmmeter shows how much resistance there is between two points along a circuit. Low resistance means good continuity.