Printed Circuit Board Test

Printed Circuit Board Test

The following procedure is used to be locate suspected breaks or short circuits in the conducting foil.

1. Remove instrument cluster from vehicle and remove all bulbs, gauges and meters.

Caution: When using ohmmeter, disconnect power from circuit being tested. Otherwise ohmmeter internal circuits will be destroyed.

2. Connect one ohmmeter test probe to applicable pin terminal for circuit to be tested. Trace each circuit from pin terminal to bulb, gauge or meter terminal in circuit with other test probe.

Note: Set ohmmeter for the low resistance scale (0 - 10 ohms) and zero meter pointer.

3. Test for continuity at each uncoated position in circuit. Ohmmeter should indicate zero ohms at each position.

Note: When circuit tracing, time can be saved by starting at the middle of the circuit. This will isolate circuit defects to one half of the circuit.

4. Trace circuit leading away from bulb or gauge terminal to ground terminal pin or ground screw.
5. Connect one ohmmeter probe to ground terminal pin and other probe to cluster metal case. Ohmmeter should indicate zero ohms.
6. Replace printed circuit board if ohmmeter indicates other than zero ohms on any test.
7. Test for short circuits between circuits. With probe connected to applicable pin for circuit to be tested, move other probe to all other pin terminals on cluster. Ohmmeter should indicate infinite resistance between circuits.