Question about 1998 Toyota 4Runner

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1998 toyota forerunner oxygen sensor wiring problem

Appx 6 " from the sensor, there is a 2-part plug connecting it to the wiring harness...somehow, the wires were pulled out of the plug, & i do not know the correct way to reattach them, since the color sceme differ differs..

from the sensor itself, the wires are a)blue, b)white, c)black, and d)black..
to the harness, the wires are A)red/white, B)white/blue, C)red, & D)brown...

i do not want to burn out my car's computer trying to find which wires
go where, & the harness display i show does not show this plug, at all..
i cannot take my smog test until this connection is made, so this info would be greatly appreciated at this time..

ie. a>B b>A c>D & d>C thank you bruce

please help me, only, if you know for certain...

Posted by on

  • edwardzesty Dec 13, 2008

    I have a 2000 2wd. same problem. my catalytic converter was ripped out by scrap metal theives and they cut the electrical connector out. I have a call into a local dealership parts manager and was only offered a price on a new wiring harness to the engine plus labor. this adds up to thousands. he told me that the toyota manual does not show which color goes to which. this is crazy i'm thinking. i'm going to call another dealership to test this statement. There are 24 possible wiring configurations. what are the wire sizes on yours? Mine are #10, #18, #16, and #16, I think.


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the best thing to do is get a 12 volt lite tester the one with the pointie end. cut your harness turn on left turn signel. with tester lite grounded tuch the ends of the cut wire from truck strip a small piece of wire covering and attach to your trailor harness when left signal works on the trailor do the right blinker the same way as for running lites turn on your park lites and see witch two wires are lit connect to trailor making shure lites are dim last wire are for brake lites now you well know where to connect to new harness good luck cj

Posted on May 21, 2010

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What codes are you getting?

Posted on Dec 18, 2010

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2 Answers

What code mean po302,,,,po135...p1705

P0302 TOYOTA - Cylinder 2 Misfire Detectedxicon.jpg CodePossible causes- Faulty spark plug 2
- Faulty ignition coil 2
- Ignition coil 2 harness is open or shorted
- Ignition coil 2 poor electrical connection
- Clogged or faulty fuel injector 2
- Injector 2 harness is open or shorted
- Injector 2 poor electrical connection
- Improper spark plug 2
- Insufficient cylinder 2 compression
- Incorrect fuel pressure
- Intake air leak
P0135 - O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 1xicon.jpg CodePossible causes- Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit open shorted to ground
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit poor electrical connection
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit fuse
- Faulty Engine Control Module (ECM)
Tech notes The code means that there is a problem with the heater element circuit of the heated oxygen sensor. The Engine Control Module (ECM) monitors how long it take the sensor to warm up and start sending an adequate signal. The code means the the sensor is taking too long to warm up. Replacing the O2 Sensor 1 usually takes care of the problem
P1705 TOYOTA - Direct Clutch Speed Sensor Circuit Fault.
This is related to the sensor that gives info about the slippage rate o fthe transmisssion to the Transmission Control Module..

Jul 15, 2012 | 1996 Toyota Camry

1 Answer

Spark plugs



1. Remove the ignition coils (lines at end this document), then return here once you have gotten the Coil
Packs off and precede with step 2 from here.
2. Clean the spark plug recesses with low pressure air. CAUTION: Wear safety glasses
when using compressed air, as flying dirt particles may cause eye injury. NOTE:
Clean the spark plug recess area before removing the spark plug. Failure to do so could
result in engine damage because of dirt or foreign material entering the cylinder head, or
by the contamination of the cylinder head threads. The contaminated threads may prevent
the proper seating of the new plug. Use a thread chaser to clean the threads of any
3. Remove the spark plugs from the cylinder head. NOTE: Allow the engine to cool before
removing the spark plugs. Attempting to remove the spark plugs from a hot engine may
cause the plug threads to seize, causing damage to cylinder head threads.
4. Inspect the spark plugs.



1. Measure the spark plug gap on the spark plugs to be installed. Compare the measurement
to the gap specifications. NOTE:
• Use only the spark plugs specified for use in the vehicle. Do not install spark
plugs that are either hotter or colder than those specified for the vehicle. Installing
spark plugs of another type can severely damage the engine.
• Check the gap of all new and reconditioned spark plugs before installation. The
pre-set gaps may have changed during handling. Use a round feeler gage to ensure
an accurate check. Installing the spark plugs with the wrong gap can cause poor
engine performance and may even damage the engine.
2. Install the spark plugs to the cylinder head. NOTE:
• Be sure that the spark plug threads smoothly into the cylinder head and the spark
plug is fully seated. Use a thread chaser, if necessary, to clean threads in the
cylinder head. Cross-threading or failing to fully seat the spark plug can cause
overheating of the plug, exhaust blow-by, or thread damage.
• Refer to Component Fastener Tightening Notice in Service Precautions.
Tighten the spark plugs to 18 N.m (13 lb ft).
3. Install the ignition coils.

1. Remove the air cleaner resonator and outlet duct.
2. Disconnect the engine wiring harness electrical connector (1) from the oil pressure sensor (2).
3. Disconnect the engine wiring harness retainers (1) from the power steering pump (2).
4. Disconnect the engine wiring harness electrical connectors (1, 4) from the following:
• The exhaust camshaft position (CMP) sensor (5)
• The camshaft position (CMP) actuator solenoid valve (6)
5. Disconnect the engine wiring harness retainer (2) from the camshaft cover (3).
6. Disconnect the engine wiring harness electrical connectors from the following:
• The engine coolant temperature (ECT) sensor (1)
• The fuel injector harness (2)
• The ignition coils (4)
• The heated oxygen sensor (HO2S) (5)
7. Disconnect the engine wiring harness electrical connector from the intake camshaft position (CMP) sensor.
8. Carefully disengage the engine wiring harness conduit from the camshaft cover, and position aside.
9. Remove the ignition coil bolts.
10. Remove the ignition coils from the camshaft cover.

1. Install the ignition coils into the camshaft cover. IMPORTANT: Ensure the ignition coil seals are properly seated to the camshaft cover.
2. Install the ignition coil bolts. NOTE: Refer to Fastener Notice in Service Precautions. Tighten the ignition coil bolts to 10 N.m (89 lb in).
3. Attach the engine wiring harness conduit to the camshaft cover.
4. Connect the engine wiring harness electrical connector to the intake CMP sensor.
5. Connect the engine wiring harness electrical connectors to the following:
• The ECT sensor (1)
• The fuel injector harness (2)
• The ignition coils (4)
• The HO2S (5)
6. Connect the engine wiring harness electrical connectors (1, 4) to the following:
• The exhaust CMP sensor (5)
• The CMP actuator solenoid valve (6)
7. Connect the engine wiring harness retainer (2) to the camshaft cover (3).
8. Connect the engine wiring harness retainers (1) to the power steering pump (2).
9. Connect the engine wiring harness electrical connector (1) to the oil pressure sensor (2).
10. Install the air cleaner resonator and outlet duct.

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa, have a nice day.

Jan 23, 2012 | Cars & Trucks

1 Answer

How do you change oxygen sensors on a 2000 hyundai sonata

Locate the two oxygen sensors on either side of the Sonata's catalytic converter on the exhaust manifold. The Sonata's oxygen sensor is gold and shaped liked a spark plug.

  • 2 Remove the Sonata's wiring harness from the end of the two oxygen sensors using your fingers. Do not damage the end of Sonata's wiring harness.
  • 3 Remove the two oxygen sensors from the Sonata's manifold using the oxygen sensor wrench.
  • 4 Apply the anti-seize compound to the threads of the Sonata's two new oxygen sensors.
  • 5 Install the two new oxygen sensors to the Sonata's manifold using the oxygen sensor wrench. Re-attach the wiring harness to the two new oxygen sensors using your fingers.
  • Oct 31, 2011 | 2000 Hyundai Sonata

    2 Answers

    Where does a oxygen sensor go on a toyota celica 2000 ?

  • Locate the upstream and downstream oxygen sensors under the vehicle near the front axle. The upstream and downstream sensors resemble spark plugs with several wires connected to them. Remove the sensors by turning them clockwise with a 22-millimeter wrench.Locate the wiring harness inside the vehicle under the center console on the front passenger side. Disconnect the electrical connectors for the oxygen sensors. Feed the wires down through the vehicle and pull them out under the car.Feed the wiring assemblies on the new sensors up through the floor of the vehicle. Reconnect the wires in the wiring harness. Screw in the new oxygen sensors with your fingers. Once they are in place, tighten them with a 22-millimeter wrench.Remove the jack stands and lower the Celica to the ground. Remove the tire blocks. There should be a sensor before the CAT converter, and one RIGHT after it.

  • May 17, 2011 | 2000 Toyota Celica

    1 Answer


    Welcome to

    The upstream oxygen sensor is typically found on the exhaust manifold that is bolted to the engine block. It may be as far up on the exhaust as the the manifold piping located in the front of the engine under the hood. The sensor looks like a plug sticking out of the exhaust piping and will be the only plug inserted into the exhaust system.


    Removal of the oxygen sensor is easier when the engine temperature is above 48CC


    ' Handle the oxygen sensors carefully in order to prevent damage to the component.

    Keep the electrical connector and the louvered end free of contaminants. Do not use

    cleaning solvents on the sensor. Do not drop or mishandle the sensor.


    Numbers in ten in parenthesis correspond to numbered components in image.

    1. Raise and support the vehicle.

    2. Disconnect the sensor harness connector.

    3. Remove the oxygen sensor.

    Bank 1 Sensor 2(1)

    Bank 1 Sensor 1(2)

    A Bank2Sensorl(3)

    A Bank2Sensor2(4)


    Important: A special anti-seize compound is used on the oxygen sensot threads. The new

    service sensors should have the compound already applied to the threads. Coat the

    threads of a reused sensor with anti-seize compound P.N 5613695 or the equivalent.

    1. Install the oxygen sensor.

    Bank 1 Sensor 2(1)

    A Bank sensor (2)

    A Bank2Sensorl (3)

    A Bank2Sensor2 (4)

    Important: Make sure that all of the harness retaining clips are intact. The harness

    must not contact any of the hot exhaust components. The HO2S pigtail has white

    tape at the intervals, indicating the proper location of each retaining clip. When

    connecting the sensor pigtail to the harness, ensure that the connector seal is

    crushed uniformly all the way around between the connectors.

    2. Connect the sensor harness connector.

    3. Lower the vehicle


    Thank you for using
    Regards, Lee Davidian

    Nov 05, 2010 | 1998 Cadillac Catera

    1 Answer

    Hard running motor trouble shooting codes p0135

    P0135 - Oxygen O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)

    This code refers to the front oxygen sensor on Bank 1. The heated circuit in the oxygen sensor decreases time needed to enter closed loop. As the O2 heater reaches operating temperature, the oxygen sensor responds by switching according to oxygen content of the exhaust surrounding it. The ECM tracks how long it takes for the oxygen sensor to begin switching. It the ECM determines (based on coolant temp) that too much time elapsed before the oxygen sensor began operating properly, it will set P0135.

    Symptoms: You will likely notice poor fuel economy the illumination of the MIL.

    Causes: A code P0135 may mean that one or more of the following has happened:
    * O2 Heater element resistance is high
    * Internal short or open in the heater element
    * O2 heater circuit wiring high resistance
    * open or short to ground in the wiring harness

    Possible Solutions:
    * Repair short or open or high resistance in wiring harness or harness connectors
    * Replace oxygen sensor (cannot repair open or short that occurs internally to sensor)

    I hope this helps, remmeber to rate and comment this.

    Oct 05, 2010 | 1998 Chevrolet Blazer

    1 Answer

    Oxygen sensor p0171 system too lean 1998 tyota camry whitch sensor to replace?

    Hello. Welcome to FixYa. Please allow us to assist you.

    If you have a P-0171 code, you do not have an oxygen sensor issue. The P-0171 relates to a dirty Mass Air Flow sensor, which will cause the other sensors to read incorrectly.

    What you need to do:

    Inspect your air filter. Replace it if it is dirty.

    Locate the Mass Air Flow sensor, it is located on the air tube, from the air filter to the intake manifold. Unplug the wiring harness, and unscrew to sensor from the tube. Using a flashlight, inspect the interior of the sensor. You will see 2 small silver wires. Are they dirty or fuzzy? If so, this is the reason for the code. Now, with a spray can of readily available brake cleaner, liberally spray the 2 small wires until they are perfectly clean. Use as much of the cleaner as you need, until the wires are perfectly clean. Let it dry out (please do NOT use compressed air, that will break the wires, and force you to purchase a sensor). After it drys out, refit it to the tube, reconnect the wiring plug, and drive the car 8-10 miles. The computer will see the proper values, and the light will go out.

    This should get you fixed up.Thanks for choosing FixYa for assistance.

    Jul 12, 2010 | 1998 Toyota Camry

    1 Answer

    Where Are The sensor Banks On The 2004 GC

    Grand Cherokee oxygen sensor locations for 4.0 and 4.7 engines



    Four wires (circuits) are used on each O2 sensor:

    • 12–volt feed circuit for the sensor heating element
    • Ground circuit for the heater element
    • Low-noise sensor return circuit to the PCM
    • Input circuit from the sensor back to the PCM to detect sensor operation

    O2S Sensor removal Never apply any type of grease to the oxygen sensor electrical connector, or attempt any soldering of the sensor wiring harness.
    1. Raise and support vehicle.
    2. Disconnect O2S pigtail harness from main wiring harness.
    3. If equipped, disconnect sensor wire harness mounting clips from engine or body.
    CAUTION: When disconnecting sensor electrical connector, do not pull directly on wire going into sensor.
    4. Remove O2S sensor with an oxygen sensor removal and installation tool.

    02S Sensor installation
    Threads of new oxygen sensors are factory coated with anti-seize compound to aid in removal. DO NOT add any additional anti-seize compound to threads of a new oxygen sensor.
    1. Install O2S sensor. Tighten to 22 ft. lbs. (30 N·m) torque.
    2. Connect O2S sensor wire connector to main wiring harness.
    3. If equipped, connect sensor wire harness mounting clips to engine or body. When Equipped: The O2S pigtail harness must be clipped and/or bolted back to their original positions on engine or body to prevent mechanical damage to wiring.

    Hope thats help (remember comment and rated this).

    Apr 29, 2010 | 2004 Jeep Grand Cherokee

    1 Answer

    T1oo xtra has a sensor on pass side over fender inside by motor its unplugged, its has a yellow harness plug, what is this


    All Toyota vehicles use Yellow wiring connectors/harness plugs for the Air Bag System, and their related components.

    More than likely, your front crash sensor has been somehow disconnected.

    Thanks for using FIxYa today.

    Jan 03, 2010 | 1995 Toyota T100 Xtracab

    2 Answers

    VSC Trac off/ VSC Trac

    how do I determine which oxygen sensor is bad on my 2003 forerunner ? the check engine light is on and also the vsc trac

    Mar 28, 2009 | 2003 Toyota 4Runner

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