Mechanics

CHEVY ENGINE FAN CLUTCH

1994 Chevrolet Blazer

Engine Performance problem
1994 Chevy Blazer V8 Four Wheel Drive Automatic 250, 00 miles

last winter my engine fan and clutch were replaced.
the engine now roars when accelerating and bogs down to what feels like a hard gear shift, I have read else where that it may be the Throttel position sensor
How do I check the TPS, could the fan clutch be faulty?
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Carl T
July 9, 2010.



Open the hood of your vehicle and locate the TPS sensor in the engine compartment. Its most common location is on the outside--to the right or left--of the throttle body or carburetor plate shaft. Here you will see a small black box with three wires coming out from its electrical connector.

Unplug the TPS electrical connector. Turn on the ignition switch but do not start the engine. Using a voltmeter, probe the connector’s terminals coming from the computer side to test for supply voltage. Touch the negative lead to the connector’s terminal ground--most likely the black wire--and the meter’s positive or red lead to the connector’s terminal reference voltage wire, a blue or gray color wire. Your meter should read a steady 5.0 volts at the terminal. If you don’t receive this voltage reading, there is an open or short in the supply wire. Turn off the ignition switch and plug the electrical connector back to the TPS.

Test the TPS for signal voltage to the computer. Insert a pin through the ground wire and another pin through the signal voltage wire and connect the voltmeter probes to the pins using alligator clips. Start the engine. As you manually open and close the throttle plate, watch the voltage readings at the meter. The voltage should gradually increase from 1 to 5 volts and back to 1 volt. If you see an erratic or no movement of voltage signal, replace the TPS sensor. Turn off the engine.

Test the TPS sensor’s resistance. This is an alternate method to test TPS sensors equipped with a variable resistor. Unplug the TPS electrical connection. Set your multimeter to ohms. Connect the ohmmeter probes to the sensor’s supply and signal wire contacts. Manually open and close the throttle plate and watch the resistance reading at the meter. The resistance should gradually increase and decrease as you open and close the throttle plate. If there is an erratic resistance change, no change, or no resistance at all, replace the TPS.

Adjust the TPS. Some sensors need to be adjusted from time to time. They are mounted with a couple of screws that allow the sensor to be rotated for adjustment. Loosen the mounting screws. With the ohmmeter connected as described in Step 4, rotate the sensor until you obtain the resistance specified in your vehicle service manual. Tighten the mounting screws and check the sensor’s resistance as described in Step 4.

Plug in the TPS electrical connector, start your engine and test for performance.