1999 Buick Century LTD

Tiny
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  • MEMBER
  • 1999 BUICK CENTURY
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 131,000 MILES
Coolant temp gauge all the way to Red, Warning light on. Replaced new senson on top of block beside the thermostat. Coolant temp at thermosta 174F, but computer reading 194F. Goes to safe mode while driving, 2nd gear and lose power. Start up again and all ok, for 10 sec. There is communication error sensor to computer, where do find diagram to help check the wires. Or what's wrong?I had new intake manifold casget installed and after this occurred.
Sunday, April 3rd, 2011 AT 4:00 PM

17 Replies

Tiny
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Do u have a leak. Is the thromastate opening?Are the fans working?
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Sunday, April 3rd, 2011 AT 5:11 PM
Tiny
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No leaks, fans working and due to high temp they are running until key is turned off.
Car was running good before intake manifold casget change. Not temp gauge jumps up just after few mils. This is in gauge/computer but not actually in the engine.
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Sunday, April 3rd, 2011 AT 5:20 PM
Tiny
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Drain some coolant out so u can see the tubes in the radiator. Start it up as the thrmostate opens youll see the coolant go up and down. When it opens youll see the coolant flowing through the tubes then rev the motor and make sure u have good curclation. Or the thrmostate needs replacment.
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Sunday, April 3rd, 2011 AT 5:50 PM
Tiny
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Engine is not over heating. Computer signal 50 deg hotter as it actually is. Today without run, it was reading 52 deg. Sensor is 3 wire plug, 1-ground, 1-when key is on sends 5v to the sensor, 1-read sensor to computer. This seems to be a wire issue sensor to computer, but there is no proper diagram to show how the wires are, or where does it get this"extra" 50 deg reading.
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Sunday, April 3rd, 2011 AT 7:25 PM
Tiny
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Youll need to ck. The codes before u start tracing wires.
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Sunday, April 3rd, 2011 AT 7:50 PM
Tiny
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THE QUESTION IS, WHAT CAUSING COMPUTER READING TO BE DIFFERENT BY 50 DEG THAN THE ACTUAL TEMPERATURE. NEW AND OLD SENSORS GIVE THE SAME READING 244 DEG. AND WHY IT HAPPENED AFTER THE INT MANIFOLD GASKET CHANGE?
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Monday, April 4th, 2011 AT 12:39 PM
Tiny
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How are u gettin the temp. Of 174 at the thrmostate
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Monday, April 4th, 2011 AT 4:58 PM
Tiny
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This is measured with temp gun. Motor doe s not overheat. I need help to solve ;why reading at computer is high a sthe actual temp is lower.
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Monday, April 4th, 2011 AT 5:14 PM
Tiny
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Hhow hot is the computer reading when its warmed up? Because 194 is the proper temp?
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Monday, April 4th, 2011 AT 5:56 PM
Tiny
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The computer starts with a ambeint temp. Never gos to 0. If the light is on your setting a code and we need it to give u a answer. After the work was done. They either they damaged a sensor, wire or connector. Sometimes they get a wire caught under the intake by mistake
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Monday, April 4th, 2011 AT 6:10 PM
Tiny
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Interesting is that the wire diagram what we have shows two wires;blk and yel. We have three wires;one ground, one which has 5v send to the sensor and one goingout to the computer. That wire is malfunctioning (I assume)as it has a high resistant as it shows hiher temp, right? If I can not solution, one thing is possible is to run new wire from sensor to computer.
Any other ideas?
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Monday, April 4th, 2011 AT 8:09 PM
Tiny
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Thats called a referance line 5v line is from the ecm. You new to ck. It for the 5v with a multi meter. That heat gun is not really going to give u a reading because of the moving air.
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Monday, April 4th, 2011 AT 8:51 PM
Tiny
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What are you talking about?
%volt is measured with multimeter, only way to do it!
Heat gun, what?
Moving air?
Is there a real mechanic available?
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Monday, April 4th, 2011 AT 9:44 PM
Tiny
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Can you shiw the wire diagram which show 3-wires from the sensor, this sensor is beside the thermostat NOT in radiator
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Monday, April 4th, 2011 AT 9:48 PM
Tiny
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The temp gun your using inst accruate. You need 12v on 1 wire and ground on 1 then 5v on the serial data line. Yes u need a multi meter to read the 5v serial data wire from the ecm.U NEED TO READ THE CODES! To trouble shoot your problem. Dont just run to a sensor. Sorry on my last responce I got 2 answers mixed up
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Tuesday, April 5th, 2011 AT 2:22 AM
Tiny
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Are sure that one wire should have 12V. The sendor already receives 5V, why 12 V. I'm readind 0 in that wire as we tought that this is the sending wire to computer and should read resistant rather than voltage. Do you have diagram that showns 3 wires from sensor?
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Tuesday, April 5th, 2011 AT 12:34 PM
Tiny
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The wire from the computer should read 5 volts. If no the ecm is bad. The sensor is operated as the temp. Closes the sensor that wire reading 0 should show a reading. When u start the car cold is the l, ijght on?
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Saturday, April 16th, 2011 AT 4:55 PM

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