Does anybody have data sheets or have data points of the sensor resistance for various levels? I want to measure the lfuel level, coolant temp and oil pressure with some data acquisition equipment, but I can't make accurate conversions without these profiles.
Thanks.

 

From my '87 FSM Electrical Diagnosis Service Manual Supplement:

Oil Pressure Sender:Fuel Gauge Sender:Coolant Temp Sender:These are measured at the cluster connector.

 

I only have the CTS chart.

 

That CTS chart is exactly what I'm looking for. Thank you! Do you know if that represents the CTS for the gauge, or if it's the one that the ECU uses? I'm not sure that they both follow the same profile, since they're both different styles of sensor.

 

Thanks to that CTS chart I was able to build a calibration equation (Steinhart–Hart equation) that will allow me to map all of my temperatures without having to resort to a lookup table.

Now if I can just find the same info for the oil pressure sender and the fuel level sender.

 

Last night I took apart an old oil sender to see what's inside. The oil pressure appears to push a plunger, which in turn rotates a sweeper pot. I'm going to assume that the sweeper pot is linear. That's provably not completely true, but it should be close.

Likewise, fuel senders use a pot too, so I'm calling that linear too.

 

I'm not certain, but my guess is that the fuel level sender is not linear. Typical GM guage that shows 1/2 tank is actually closer to 1/4 tank. It's calibrated so that you can drive 50 miles without moving the needle, the purpose of which is to phsyche out the consumer into thinking he's getting great gas mileage. It reduces warranty complaints.

 

I think most of that comes foom the shape of the tank and the gaugeitself, and not necessarily the sender.