The International CBX Owners Association

Hi guys,

So i've searched and couldn't find any topic that deals directly with this problem. Since the purchase of my 1979 CBX, the oil pressure light has never been on.

Swapped the oil pressure light bulb, no luck

Found out yesterday with FalldownPhil that the oil pressure switch is still good, through some tests that he ran.

Cleaned the contact for the bulb and add dielectric grease, still no luck.

Then i decided the leave the gauges off the bike turn the ignition on, and use multimeter to check the contacts on the 2 gauge connectors (on the motorcycle side). The smaller connector contact with 4 pins all shows current reading when I turn the ignition on and turned on the high beam. The larger connector with 4 pins and 2 blank, the 2 pins for the neutral switch shows current as the bike is in neutral, but the last 2 pins (for oil pressure) shows no current running through it at all.

So no current at the oil pressure light connector on the motorcycle side when the ignition is on means the power link to the battery must be severed.

So bad cable then or maybe just bad contact? How does the oil pressure light draw power from the battery?

The oil pressure switch works sort of backwards. With no oil pressure, the 'contacts' in the switch are closed - you should see continuity across the switch, which I assume Phil showed you. This completes the circuit to the oil pressure light and you should see voltage (not current) there, which I think you correctly assumed. When oil pressure forces the switch open, the circuit opens and the light goes out. If you have nothing at the bulb plug-in, then you need to 'ring out' that wire. I think you will find that you do not have continuity the length of the circuit, meaning a break somewhere. Start by doing it in steps. Unplug the 2-pin connector under the right side cover and check continuity from there to the switch. Then check from the connector to the headlight, then headlight to the gauge harness. Somewhere you have a break.

Dave

Thank you so much for the advise Dave! Unfortunately my work take so much of my time, it is so hard to find time lately to troubleshoot and work on the CBX. Would swapping out the wiring harness with a new one usually fix this issue?