1990 Geo Prizm Base, 4D Hatchback, StandardFACTORY OEM SERVICE PROCEDURE

Engine Controls - Sensor Operating Range Charts: Introduction: Notes

NOTE: All voltage tests should be performed with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure.

Sensor operating range information can help determine if a sensor is out of calibration. An out-of-calibration sensor may not set a trouble code, but it may cause driveability problems.

COOLANT TEMPERATURE SENSOR RESISTANCE EXCEPT PRIZM/GSi)

Temperature °F (°C) Resistance Ohms
-40 (-40) 100,700
0 (-18) 25,000
20 (-7) 13,500
40 (4) 7,500
68 (20) 3,400
100 (38) 1,800
160 (70) 450
212 (100) 185
KNOCK SENSOR RESISTANCE TEST (PRIZM GSi)

Condition Resistance Ohms
*(1) 3,300-4,500
(1) Measure resistance between sensor terminal and engine block.
MAP SENSOR VOLTAGE TEST (EXCEPT PRIZM GSi)

Altitude Feet (Meters) (1) Signal Voltage
Below 1,000 (304) 3.8-5.5
1,000-2,000 (304-610) 3.6-5.3
2,000-3,000 (610-914) 3.5-5.1
3,000-4,000 (914-1219) 3.3-5.0
4,000-5,000 (1219-1524) 3.2-5.8
5,000-6,000 (1524-1829) 3.0-4.6
6,000-7,000 (1829-2133) 2.9-4.5
7,000-8,000 (2133-2438) 2.8-4.3
8,000-9,000 (2438-2473) 2.6-4.2
9,000-10,000 (2473-3048) 2.5-4.0
(1) Measure voltage at appropriate ECU terminals. See WIRING DIAGRAMS .
MANIFOLD AIR TEMPERATURE (MAT) SENSOR RESISTANCE TEST (EXCEPT PRIZM/GSI)

Temperature °F (°C) (1) Resistance Ohms
-40 (-40) 100,700
0 (-18) 25,000
20 (-7) 13,500
40 (4) 7,500
68 (20) 3,400
100 (38) 1,800
160 (70) 450
212 (100) 185
(1) Measure resistance across sensor terminals.
OXYGEN SENSOR VOLTAGE TEST

Condition (1) Volt
Lean .1
Rich .9
(1) Engine running in closed loop.
THROTTLE POSITION SENSOR (TPS) RESISTANCE TEST (PRIZM GSi)

Condition Resistance (Ohms)
Between Terminals E2-IDL (1)(2) Continuity
Between Terminals E2-IDL (2)(3) No Continuity
(1) With .014" (.35 mm) feeler gauge installed between stop screw and lever.
(2) E2 is Brown wire terminal and IDL terminal is Blue wire terminal.
(3) With .023" (.58 mm) feeler gauge installed between stop screw and lever.
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  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
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