View single post by Mark Rosenbaum
 Posted: 01-27-2007 11:08 pm
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Mark Rosenbaum

Joined: 03-12-2005
Location: Kingman, Arizona USA
Posts: 532
Your test should have caused all the instrument pod bulbs to illuminate.  Since only the oil gauge light did, then either all the other bulbs are bad, or there are multiple defects in the instrument pod wiring harness, or a PO did something inappropriate.

The oil gauge light is shown on the wiring diagram for US cars as the hazard warning switch light, and owes its existence to a federal mandate requiring such a light.  IIRC this light connects to the pod harness via a pair of bullet connectors.  If a problem exists with the grounds in the pod harness, a PO might have hooked the oil gauge light's ground wire to the ground-side bullet connector for the clock, as a stopgap measure, and never got around to actually fixing the problem.

IIRC the various instruments (and their light bulbs) are connected to the pod harness ground junction through wires that attach to their cases.  Rusty cases will disable these connections.  The pod harness ground junction is wired to pin 4 of one of the pod connectors and thence to the lefthand ground junction in the main underdash wiring harness.