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Tim's Auto Repair
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1991 chevy: o2 sensor..2wd..Now the truck will intermittently stumble

Resolved Question:

I just replaced the O2 sensor on my 1991 chevy s-10/4.3 2wd truck due to a code showing problems with the sensor. Now the truck will intermittently "stumble" under acceleration load and on some inclines. I wonder if I have a defective sensor since this problem didn't occur until I changed ther old one out.

Craig U.
Submitted: 5 years ago.
Category: Chevy
Expert:  Tim's Auto Repair replied 5 years ago.

hi

what is the code #'s areyou getting?

Customer: replied 5 years ago.

I think it was #13 which corresponded to the o2 sensor in the book that came with the code reader.

 

Thanks

 

Expert:  Tim's Auto Repair replied 5 years ago.

hi

i dont think the problem is the o2sensor itself here..i think it may be the wiring harness to the sensor..check the wires to make sure they are no damaged...also,you may want to clean the harness connector at the ecm[computer] with radio contact cleaner...the info below may help you

thanks

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1991 Chevy Truck S10/T10 P/U 2WD V6-262 4.3L
Computers and Control Systems Testing and Inspection, Diagnostic Trouble Code Tests and Associated Procedures: Manufacturer Code Charts, DTC 13, Powertrain Controls - ECM/PCM
01_gmtda405003037-002.pngCode 13 - Oxygen Sensor Open Circuit

27_gmtda405003037-001.pngWiring Diagram For Code 13 - Oxygen Sensor Open Circuit



CODE 13 - OPEN OXYGEN SENSOR CIRCUIT


CIRCUIT DESCRIPTION:

The ECM supplies a voltage of about .45 volt between terminals "D7" and "E15". (If measured with a 10 megohm digital voltmeter, this may read as low as .32 volts.) The O2 sensor varies the voltage within a range of about 1 volt if the exhaust is rich, down through about .10 volt if exhaust is lean.

The sensor is like an open circuit and produces no voltage when it is below 315~C (600~F). An open sensor circuit or cold sensor causes "Open Loop" operation.


TEST DESCRIPTION: Step numbers refer to step numbers on diagnostic chart.

1. Code 13 will set when:

^ Engine at normal operating temperature
^ At least 2 minutes engine time after start.
^ Oxygen sensor signal voltage steady between .35 and .55 volts.
^ Throttle position sensor signal above 4%.
^ All conditions must be met for about 60 seconds. If the conditions for a Code 13 exist, the system will not go "Closed Loop".

2. This will determine if the sensor is at fault or the wiring or ECM is the cause of Code 13.

3. In doing this test, use only a high impedance digital volt ohm meter. This test checks the continuity of CKT's 412 and 413 because if CKT 413 is open the ECM voltage on CKT 412 will be over .6 volts (600 mv).


DIAGNOSTIC AIDS:

Normal "Scan" voltage varies between 100 mv to 999 mv (.1 and 1.0 volt) while in closed loop. Code 13 sets in one minute if voltage remains between .35 and .55 volts, but the system will go "Open Loop" in about 15 seconds.

SEE DIAGNOSIS BY SYMPTOM - NO TROUBLE CODES STORED.
Please ACCEPT my answer by clicking the accept button, so I can get credit for my work.i don't receive commission unless you do ..I'm not always going to be giving you good news,so please don't let this stand in the way of you accepting my answer.it does not cost you more money.we will still be able to communicate.please understand,i can not see,hear or touch the vehicle and only know what you tell me. Bonuses and positive feedback are appreciated!if you are not satisfied with my answer,please do not leave bad feed back,i will gladly opt out and let another expert handle the question.if i have sent any diagrams,please print them.they will only stay on here for an hour or so.PLEASE ASK IF YOU NEED MORE HELP
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