Alan

Andrew:

Sensor 07 - "Oil Pressure Indication" = Warning light On/Off
Sensor 08 - "Oil Pressure Sensor" = Variable Gauge Reading

Alan

AO

That makes sense, but the manual doesn't seem to read that way - maybe that's what's confusing me. Wouldn't be the 1st time.

Alan

What happends when you display it ? was it Sensor 07 or Sensor 08 that got you your real pressure display?

Alan

AO

Actually, the "OILPRESSURE" read out comes after you've gone through all nine sensors (see bottom of page 10).

I was just curious what the difference was between the 2 sensors. However, before I stumbled on the point hat you could run the car while viewing the oil pressure readout, I noticed that the "oil pressure indication" and the "oil pressure sensor" read about the same. It seemed "overly redundant" at the time. I hadn't considered the warning lamp (indication).

So, if I were to experience a low oil pressure warning light, I could verify via this test if it was indeed a low pressure warning, or if it were a faulty signal.

borland

Good point Andrew.

It must be that there are two analog to digital converters on the same line. In the guide, the instrument and display data tables are the same for sensors 07 and 08, but the codes are different. Notice the range of codes is quite different between the two.

So it could be that one is for calculating the high range and the other is for the lower range of pressures.

The wiring diagram shows a separate switch input at the oil pressure sensor that leads to another input at the digital cluster.

AO

Would any of you guys happen to have a verion of the I.C. diagnosis book that includes the airbag, PSD, etc, values? I think there is a lot more we can do with the digital I.C., we just don't know it.

borland

Andrew,

Sorry, I only have the Morehouse CDs, so you probably have everything I do. Unfortunately, the manual wasn't update after 89', so PSD is undocumented. Yes, there are some other undocumented, and unused pins going to the Instrument Cluster, like "Air Charge" (that must have been the SC option we never heard about.

Before replacing the oil pressure sender, you could also measure the sender's ohms and compare those with what's shown in the Service Guide for various readings on the display. The best place to connect an ohm meter is at the relay/fuse panel (central electrics, or CE). If you take a look at the WSM wiring diagrams, you'll see that the wires are routed from the digital cluster to the pressure sender through the CE panel.

Take a look at Sheet 4 which includes the instrument cluster wiring. You'll find the oil pressure is monitored by two wires, the signal wire (Sender Oil Pressure), and the ground wire (Sender Ground). The Sender Oil Pressure wire runs to connector "G" on the Panel, specifically, pin 12 of connector "G". I also comes out at pin 22 of connector "E". You can also see all the connectors annotated on the diagram of Sheet 12.

Same for the Sender Ground. Pin 25 of connector "G", or at connector "E", pin 15.

You should be able to take ohm readings at these connectors without removing the connector plugs from the socket. Wire color will help determine the correct pin. May need to slip a thin wire into the wire end to make contact with the terminal.

Vilhuer

Its best to measure sender ohms directly from it. This will take engine wiring harness out of the equation also. Connector near plus post in engine bay is very good suspect for excess resistance in wiring.