TEST OR INSPECTION
Remove rings, wristwatches, neck chains, and any other jewelry before working
around vehicle. Jewelry can catch on equipment and cause serious injury. Jewelry
and tools may short across electrical circuits and cause damage to equipment, or
severe burns or electrical shock to personnel.
Release TANK TO PUMP switch (WP 0004). Remove cab instrument panel
A (WP 0311). Remove relay 12 (WP 0402). While an assistant puts cab TANK TO
PUMP switch to close position (WP 0004), check for 22 to 28 VDC between cab power
distribution wire harness wire 2770 (blue) at relay 12 connector, terminal 1 and a known
If 22 to 28 VDC are not present, go to Step 16.
Turn battery disconnect switch to OFF position (WP 0007). Check for continuity across
cab power distribution wire harness wire 1640 (black) from relay 12 connector, terminal
2 to a known good ground.
If there is continuity, replace relay 12 (WP 0402).
If there is no continuity, replace cab power distribution wire harness
and block (WP 0441).