The reading was high resistance -a few hundred K - scanner showed neg 30 F.
The resistance did change with temperature but off by a suspicious factor of about 100, made me doubt myself the meter or the chart.
Changed meters and plopped a 2K resistor across the harness- gave me a nice 90 deg F reading, so we know the chart and meter are correct.
PS: later discovered Mouser have the Delphi part under the GM part number, the advantage would be cheap overnight shipping to most places.