Discovery I (LJ) V8-3.9L (1994)
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An LED test light is used for checking voltage signals on components where an ordinary test light cannot be used, as it will not damage computer
circuits. This is the only type of test light that should be used for testing any electrical circuit.
ECU CIRCUIT TESTER
TEST LIGHT
J-34730-2
This is another type of LED test light which is a bulb type tester that will plug into most two-pin electrical connectors to test the signal of an ECU circuit.
This type of tester is ideal for fuel injection diagnoses and will not damage ECU's. The number listed is Kent- Moore's part number for this tester;
however, they should be readily available through other tool and equipment sources.
JUMPER WIRE
A jumper wire is the simplest type of electrical troubleshooting tool, and is used to bypass a portion of a circuit. The jumper wire can be used to bypass
switches and apply power directly to a load device. They can also be used to provide a good ground for the circuit or load device.
NOTE: A fused jumper wire would ensure that tested circuits arc not damaged.
CAUTION: NEVER USE A JUMPER WIRE TO BYPASS THE LOAD DEVICE. THE LOW RESISTANCE OF THE JUMPER WIRE IN
PARALLEL WITH THE LOAD DEVICE WILL CAUSE EXCESSIVE CURRENT TO FLOW THROUGH THE CIRCUIT, WHICH WILL
OPEN THE FUSE OR BURN THE WIRE.
THE INDUCTIVE AMMETER MULTIPLIER (x10)
An inductive ammeter multiplier (x10) can be used to improve the measurement of small current levels. For example, most ammeter scales will not
visibly register the movement between 2 and 2.5 amps. Using the inductive ammeter multiplier (x10), this movement would read the change as 20 to 25
amps. The multiplier makes one amp look like ten amps to the meter. Therefore, any change in amperage appears ten times any actual change.
TO MAKE THE MULTIPLIER, use ten feet of #16 gauge wire, two alligator clips (25 amp type), and electrical tape. Proceed as follows:
1. Wrap the wire around a round tube (like an old ignition coil) exactly ten times, leaving approximately a foot of wire on each end for the alligator
clips.
2. Remove the wire from the form and wrap it with electrical tape (the final product should look like a doughnut).
3. Attach the alligator clips to the two ends of the wire.