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When diagnostic tool is connected,some data seems not to be correct,while engine not in run,throttle amount is 99%,while TPS is disconnected,also idle increase switch is disconnected but appear YES

All wires are correct without any short circuit to plus or minus

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  • Russell Mower
    Russell Mower Apr 19, 2015

    in 87 the system is a pos, do you have 5v reference voltage to tps, iac and cts, if not ecm problem

  • Russell Mower
    Russell Mower Apr 19, 2015

    the scanner will be marginal at best. are you using an otc or another brand scanner

  • aliaaaa
    aliaaaa Apr 20, 2015

    this is another brand.yes i have 5 volt on mentioned sensors.



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No shorts. Did you check the return signal wires for short to power? If you have the power on the return wires, then it is shorted to power or the PCM is shorted internally. If you have access to another scanner, I would use it and make sure your scanner isn't malfunctioning.

Posted on Apr 19, 2015

Testimonial: "I changed the ECM but problems still exist. I have not other scanner to recheck I checked returned signal to ECM like return from coolant temp sensor or TPS ,I observed no power.i think this values come from other thing(s) to ECM and cause to appear wrong amount. furthermore,with this problem engine running in high RPM as lowering is not possible at idle condition."

  • 6 more comments 
  • aliaaaa
    aliaaaa Apr 19, 2015

    "I changed the ECM but problems still exist. I have not other scanner to recheck I checked returned signal to ECM like return from coolant temp sensor or TPS ,I observed no power.i think this values come from other thing(s) to ECM and cause to appear wrong amount. furthermore,with this problem engine running in high RPM as lowering is not possible at idle condition."

  • Randy Ohler Apr 19, 2015

    Did the first ECM show the same problems? Has there been any other work down on the car? if so what?

  • aliaaaa
    aliaaaa Apr 19, 2015

    yes,showed same.

  • aliaaaa
    aliaaaa Apr 19, 2015

    i checked all ECM pins one by one.according to diagram all wires were ok.i disconnect all sensors connectors but throttle was 99%.hi pressure was yes.coolant temp was 40 celcious

  • Randy Ohler Apr 19, 2015

    Disconnect the engine harness if you can, then read it again. If you can't, then you'll have to open the harness and start looking at and separating the wires. The possibilities for your problem are, Both ECM's were bad in the same spot(very unlikely), some one changed the engine and used the engine harness on it and the pin outs don't match the pins in the cars harness(seen it happen too many times). or there are shorts in the harness. Yes you checked shorts for the couple of sensors, but there are many wires. If can post schematics, this would help me. Also year make and model, plus engine size.

  • Randy Ohler Apr 19, 2015

    Also, just have to ask, did you reconnect everything and the car still had the same problems?

  • aliaaaa
    aliaaaa Apr 20, 2015

    i disconnected the harness compeletly.i checked all wires.all input and out put voltages..i guess everything is ok.i have to mention the main problem for car is high idle speed and sometimes engine shutdown after running and put in N position(lowering idle speed and engine turn off)i reconnect all sensors and wires and again throttle is 99% while engine is not run.also RPM showes 6329!

  • Randy Ohler Apr 20, 2015

    You have a scanner, check all the other computers on the car. If one is not reading, unplug it. unplug any and all that won't read. See if the car goes normal. If you have to unplug the BCM and or security, the car MUST be running. Or it will not restart. The PCM will just into default mode. I have run into this twice where another computer was sending false signal or interrupting the PCM signal.


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  • Cars & Trucks Master
  • 372 Answers

What kind of vehicle, year is important if its a mid nineties car the switch from obd1 to obd2 took a couple years and not very accurate are you reading live data or freeze frame data

Posted on Apr 19, 2015

Testimonial: "that's BUICK CENTURY 1987 limited. how can I realize this data are not freeze data? for your info. I have checked all wires from/to ECM."

  • aliaaaa
    aliaaaa Apr 19, 2015

    "that's BUICK CENTURY 1987 limited. how can I realize this data are not freeze data? for your info. I have checked all wires from/to ECM."



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I have 1995 Chev S10 with a 2.2L. It stubles from stop bad. I have replaced fuel filters and tuned it up,no help.

Test the tps using procedure below.

Throttle Position Sensor (TPS)
The Throttle Position Sensor (TPS) is connected to the throttle shaft on the throttle body. It is a potentiometer with one end connected to 5 volts from the VCM and the other to ground. A third wire is connected to the VCM to measure the voltage from the TPS. As the throttle valve angle is changed (accelerator pedal moved), the output of the TPS also changes. At a closed throttle position, the output of the TPS is low (approximately 0.5 volts). As the throttle valve opens, the output increases so that, at wide-open throttle, the output voltage should be approximately 4.5 volts. By monitoring the output voltage from the TPS, the VCM can determine fuel delivery based on throttle valve angle (driver demand).


See Figures 1, 2 and 3

Backprobe with a high impedance voltmeter at TPS ground terminal and 5 volt reference signal terminal.
With the key ON and engine off, the voltmeter reading should be approximately 5.0 volts.
If the voltage is not as specified, either the wiring to the TPS or the VCM may be faulty. Correct any wiring or VCM faults before continuing test.
Backprobe with a high impedance voltmeter at the TP signal terminal and the sensor ground terminal.
With the key ON and engine off and the throttle closed, the TPS voltage should be approximately 0.5-1.2 volts.
Verify that the TPS voltage increases or decreases smoothly as the throttle is opened or closed. Make sure to open and close the throttle very slowly in order to detect any abnormalities in the TPS voltage reading.
If the sensor voltage is not as specified, replace the sensor.


Fig. Fig. 1: Common Throttle Position Sensor (TPS) wiring diagram (wire color, terminal identification/location may vary on certain models)


Fig. Fig. 2: Using jumper wires and high impedance voltmeter, test between the sensor ground and reference terminals, the voltage should be approximately 5 volts


Fig. Fig. 3: Next test between the sensor signal and ground terminals, verify that the TPS voltage increases or decreases smoothly as the throttle is opened or closed.


Except 1998-99 2.2L Engines
See Figure 4


Fig. Fig. 4: Common Throttle Position Sensor (TPS)
Disconnect the negative battery cable and remove the air cleaner and if equipped, the gasket and bracket.
Disengage the electrical connector.
Unfasten the two TPS attaching screw assemblies.
Remove the TPS from the throttle body assembly.
Remove the TPS seal.

To install:
Install the TPS seal over the throttle shaft.
With the throttle valve closed, install the TPS on the throttle shaft.
Rotate it counterclockwise, to align the mounting holes.
Install the two TPS attaching screws.
Tighten the screws to 18 inch lbs. (2 Nm).
Engage the electrical connector.
If equipped, install the bracket and gasket air cleaner and gasket.Connect the negative battery cable.

1998-99 2.2L Engines
Disconnect the negative battery cable and remove the air cleaner outlet resonator.Remove the throttle body assembly.Unfasten the two TPS attaching screw assemblies.Remove the TPS from the throttle body assembly. To install:
With the throttle valve closed, install the TPS on the throttle body.Install the two TPS attaching screws. Tighten the screws to 27 inch lbs. (3 Nm).Install the throttle body.Install the air cleaner outlet resonator.Connect the negative battery cable.

Aug 20, 2017 | Cars & Trucks


TPS faults and how to fix

1.3b) TPS Throttle Position Sensor faultsSymptoms of faulty TPS:
Associated OBD2 error codes DTCs: P0121 - P0123

  • Poor starting: The engine may start and then stall immediately.The engine may be encouraged to keep running by slowly pressing the accelerator pedal: pressing too quickly may again stall the engine.
  • Erratic/fast idling: The idle may be so erratic as to have some impact on the automatic gear shift characteristics and may actually prevent gear shifts. The engine idle speed may be increased above normal if the TPS fails to report that the throttle is closed. After the engine has been run at high speed the engine may take longer than is usual to return to idle as the ECU will not be able determine how quickly to shorten the injector cycles.
  • Engine hesitancy/ jump in revs: Engine may fail to respond quickly to the accelerator pedal input or may suddenly jump in revs inappropriate to pedal movement. When working properly the TPS should instantaneously signal the rapidly opened throttle position to the ECU. The speed of this signal is much quicker than any similar signal sent from Manifold Air Pressure (MAP) sensor or MAF/IATequivalent. The ECU responds by increasing the fuel injection volumes to match the rapid increase in air volume. If the TPS fails to send the correct signals, the engine will seem to "hesitate" as the throttle is applied as the ECU looks to the other (slower) sensors to determine engine status. A sudden blip of the accelerator at idle can stall the engine (see above - poor start) as the ECU reacts too slowly to increase the injection time to match the sudden intake of air.
  • Engine Misfire: Spurious, beyond normal range, signals from the TPS causes the ECU to set inappropriate fuel injection cycles resulting in misfire.Detected misfire leads to a check engine light(CEL); mal-function indicator lamp (MIL). Cylinders with misfire events detected by the knock sensor may be shut down (disable specific injectors) by the ECU to prevent engine damage.

Note: - With the TPS disconnected the ECU depends on the slower signals it receives from the Mass Air Sensor (MAS) and/or the Manifold Air Pressure (MAP) sensor along with feedback from the oxygen sensor to help regulate engine speed and fuel injection cycle.

How to check? The socket for electrical connection with the TPS has 3 pins, one for 'ground', one for 5 volts 'reference' and a third (generally the middle one) for 'signal' output. Back probe the signal pin in the connector to the TPS. Attach the positive lead of a voltmeter to the probe and measure the voltage output as the throttle plate is rotated. If working correctly the meter should show a voltage consistent with the throttle position from approximately 1 volt when closed and 5 volts when fully open. What is looked for is smooth voltage increase with throttle change.If there are drop outs in the throttle transition voltage signal or if there is no transition then the TPS is faulty.

How to fix? If the track is dirty causing drop outs, try cleaning it with residue-free electrical cleaningspray. If the track is worn it is perhaps easiest toreplace the complete device. In some instances it may be possible to adjust the location of the central mount of the TPS contact arm along the throttle shaft by a few millimeters and in the process cause a fresh concentric region of track to be used

NEXT 1.4) Idle Air/speed control valve

on Jul 15, 2011 | Mercedes-Benz E-Class Cars & Trucks

1 Answer

Cannot get my 2009 colorado into program mode to set tps sensor

What engine ? Are you talking about Throttle Learn ? Did you replace throttle body ?
The engine control module (ECM) learns the idle position of the throttle plate to ensure the correct idle. The learned airflow values are stored within the ECM. These values are learned to adjust for production variation and will continuously learn during the life of the vehicle to compensate for reduced airflow due to coking. Anytime the throttle body airflow rate changes, for example due to cleaning or replacing, the values must be relearned.
A vehicle that had a heavily coked throttle body that has been cleaned or replaced may take several drive cycles to learn out the coking. To accelerate the process, the scan tool has the ability to reset all learned values back to zero. A new ECM will also have values set to zero.
The idle may be unstable or a DTC may set if the learned values do not match the actual airflow.

Throttle Learn
With Scan Tool-Reset
Ignition ON, engine OFF. With a scan tool, perform the Idle Learn Reset in Module Setup.
Start the engine, monitor the TB Idle Airflow Compensation parameter. The TB Idle Airflow Compensation parameter value should equal 0 percent and the engine should be idling at a normal idle speed.
? If the engine is not idling normally, proceed with the Learn portion of the diagnostic.
Clear the DTCs and return to the diagnostic that referred you here.

May 16, 2017 | Cars & Trucks

3 Answers

2002 rav4 2.0; when engine is hot doesn't idle and give hard start: tps,GDI,egr,fuel pump,spark plugs and coil are all okay..when its cold first key the engine is fired up

Crank sensor , cam sensor , temp. sensor , Need to have a diagnostic scan tool hooked up ! one that can read engine sensor data !

Apr 22, 2015 | 2002 Toyota RAV4

1 Answer

My 89 Seville STS started to idle high sometimes but not all the time. Now it seems to be doing it mostly all the time. I just replaced the ISC myself with no change. Is there something else I can...

Yes, there is a procedure to get the engine to idle correctly. Turn engine off, key on Open the throttle and let in snap shut against the minimum air screw. The throttle angle displayed in diagnostics on ECM parameter ED01 TPS -1.0 to + 1.0. The TPS should be adjusted to fall into this parameter. After that has been done. Connect a wire from the -side of battery to terminal c on the isc motor. and a wire to the + side of battery to terminal d. The plunger should be at its highest position against the throttle lever to adjust. This may take a few times of applying power to get it to ratchet to full ext. The TPS parameter should be at 10.5 to 11.5 on the diagnostic center. Adjust by turning the plunger on the ISC. Press the cool blue button and the off button to get the diagnostic function up. Any more question please reply as I have a service manual and fixed my 89 seville for this problem.

Aug 21, 2011 | 1989 Cadillac Seville

1 Answer

P0121 and p0068 on a 2003 dodge ram 1500 replace the throttle position sensor and the idle air sensor at the same time then ran for a week with no problems then the truck started idling up at random then...

P0121 The Throttle position sensor is a potentiometer that measures the amount of throttle opening. As the throttle is opened, the reading (measured in volts) goes up. The powertrain control module (PCM) supplies a 5 Volt reference signal to the throttle position sensor (TPS) and usually a ground also. A general measurement is: at idle = .5 Volts; full throttle = 4.5 Volts. If the PCM detects that the throttle angle is greater or less than it should be for a specific RPM, it will set this code.
Potential Symptoms Symptoms of a P0121 trouble code could include:
  • Malfunction Indicator Lamp (MIL) illumination (Check Engine Light or Service Engine Soon light)
  • Intermittent stumble on acceleration or deceleration
  • Blows black smoke on acceleration
  • No start
Causes A code P0121 may mean that one or more of the following has happened:
  • TPS has intermittent open or short internally
  • Harness is rubbing and causing an open or short in the wiring
  • Bad connection at the TPS
  • Bad PCM (less likely)
  • Water or corrosion in connector or sensor
Possible Solutions 1. If you have access to a scan tool, see what the idle and WOT (wide open throttle) readings are for the TPS. Check if they're close to the specifications mentioned above. If not, then replace the TPS and re-check.

2. Check for an intermittent open or short in the TPS signal. To do that, you can't use a scan tool. You'll need an oscilloscope. The reason is because scan tools take samplings of many different readings over just one or two data lines and can miss an intermittent drop out. Hook up your oscilloscope and watch the signal. It should sweep up and down smoothly with no drop outs or spikes.

3. If no problems were noticed, perform a wiggle test. Do this by wiggling the connector and harness while watching the pattern. Does it drop out? If so, replace TPS and re-check.

4. If you have no TPS signal, check for 5 Volt reference at the connector. If it's present, check the ground circuit for open or shorts.

5. Make sure the signal circuit isn't 12V. It should never have battery voltage. If it does, trace circuit for short to voltage and repair.

6. Look for any water in the connector and replace TPS as necessary.
P0068 Symptoms - Engine Light ON (or Service Engine Soon Warning Light)
- Lack/Loss of power
- Engine rough idle Possible causes - Large vacuum leak
- Leaking air duct system
- Mass Air Flow (MAF) poor electrcial connection
- Manifold Absolute Pressure (MAP) poor electrcial connection
- Faulty Mass Air Flow (MAF) sensor
- Faulty Manifold Absolute Pressure (MAP) sensor
- TP sensor not seated properly.
- Faulty Throttle Position (TP) sensor.
- Dirty throttle body
When is the code detected? The Powertrain Control Module (PCM) monitors operation rationality check by comparing sensed throttle position to mass air flow readings
P0068 DODGE Description The Powertrain Control Module (PCM) monitors a vehicle operation rationality check by comparing Throttle Position (TP) to Mass Air Flow (MAF) readings. If, during a self-test, the comparison of the TP sensor and MAF sensor readings are not consistent with the calibrated load values, the test fails and a diagnostic trouble code is stored in continuous memory.

Jun 05, 2011 | Dodge Ram 1500 Cars & Trucks

1 Answer

2004 KIa Sedona LS Diesel 2.9 At 2000 revs the engine management light comes on & remains on till the ignition is switched off. On restart it is off until you hit that rev band. The car seems to run...

code p 1120 refers to throttle position sensor (TPS)
that unit responds to the accelerator pedal movement (APP)
===causes --faulty TPS--wiring -- poor connections-- TPS out of adjustment

symptoms include engine light on---no throttle response
reference site is www.engine -.comcodes

Nov 12, 2017 | 2004 Kia Sedona

1 Answer

What does the code po85 mean for a 1994 cadillac deville

It means that the throttle body is dirty and the deposits in the throttle bores are restricting air flow at idle to the point that the idle speed control has no more authority to maintain the correct idle speed.

Take the air cleaner off, hold the throttle wide open and look down the throttle bores. Spray the throttle bores with carb cleaner and scrub the bores and backside of the throttle blades with an old toothbrush. Cleaning the deposits off the bores and throttle blade backsides it will restore the idle air flow to the correct level. When the throttle body is clean, disconnect the battery negative cable for 60 seconds to reset the idle learn offsets to the "clean throttle body" default values.

While you are in the throttle body and looking down the bores....see the two tubes sticking up at you from the intake manifold floor just below the throttle blades...??? Those are the EGR tubes and they are NOT supposed to be full of carbon and crud. Rod them out thoroughly with a piece of stiff wire to remove the deposits. Go all the way down thru the tubes to the cast passage below and make sure that they are clean and unrestricted so that the proper amount of EGR can flow.

Turning the key to the run position extends the ISC anticipating a restart, so if the setting is incorrect it would not erase a hard code. Just turning the key to run would light up both the service soon and service now lights as a bulb check, in other words, letting you know the bulbs work. Do you have the factory service manual?

The ISC adjustment is simple on this car. With the engine running and at operating temperature, You raise the throttle arm slightly with your right hand and push the shaft of the ISC in to fully retract it with your left hand. With constant pressure on the ISC shaft it will slowly retract. The very second it bottoms, you quickly remove the wiring connector to the ISC. Now you should have a very low idle and a gap between the throttle arm and the tip of the ISC. Approx. 0.060 of an inch. Once you know the gap is correct, shut off the engine, wait 10 seconds and reconnect the ISC wiring. Restart the engine and the ISC is set to spec. The TPS setting must be verified at this time. At minimum idle, ISC not touching the throttle arm, and unplugged, the TPS should be reading approx .0 or .1. Once the ISC is reconnected, you should see a TPS reading of approx. .5 at idle. with the A/C off.

A hard code can be erased but will continue to reset as long as the reason for it has not been corrected. Idle learn procedures were designed into later year engines with multi port fuel injection to adjust idle regardless of the amount of coke build up within the throttle body. Your fuel injection system does not build up coke or deposits because the 2 injectors spray down thru the throttle body, effectively cleaning the throttle body while running. Alot of owners adjust the ISC as if it were a throttle stop screw on a carb. guessing as they go. The ISC and TPS "MUST" be in sync to get the best off throttle response and smoothest idle. Adjusting the ISC without verifying gap or TPS voltage usually results in a surging or too high warm idle. You say the car failed at idle. For what reason? CO or HC? or idle too high?

Tell us news.

Jul 20, 2010 | 1994 Cadillac DeVille

1 Answer

Adjustable throttle position sensor

I'm assuming you have the 3.3l v-6. When I look up the part, it seems to have slotted holes. Therefore, it is designed to be adjusted after installation. If your tps has these slotted bolt holes, adjust it to satisfy the settings in the test procedure below.
  1. Remove air cleaner. Disconnect the TPS harness from the TPS.
  2. Using suitable jumper wires, connect a digital voltmeter J-29125-A or equivalent to the correct TPS terminals A and B.
  3. With the ignition ON and the engine running, The TPS voltage should be 0.3-1.0 volts at base idle to approximately 4.5 volts at wide open throttle.
  4. If the reading on the TPS is out of specification, check the minimum idle speed before replacing the TPS.
  5. If the voltage reading is correct, remove the voltmeter and jumper wires and reconnect the TPS connector to the sensor.
  6. Reinstall the air cleaner.

Jul 29, 2017 | 1991 Oldsmobile Cutlass Ciera

2 Answers

How to change a throttle position sensor on a 94 ford f150 5.0 4x4

How to Replace a Throttle Position Sensor
(DIY & Save up to $135.75 ) - Time: 2.1 hours

1. Throttle Position Sensor - $ 55.44

1. Scan Tool
2. Screwdriver
3. Multimeter

1. Locate the OBD data link connector (DLC). Refer to your owner’s manual for the specific location.
  • Tip: The OBD-I data link connector is usually located in the engine compartment near the battery or the fuse box. The OBD-II connector (post 1995 cars) is usually located beneath the instument panel next to the steering column.
2. Turn your key to the“ON” position. Do not start the engine.

3. Plug your scan tool into the OBD data link connector. Turn on the scan tool and select the appropriate steps to read the diagnostic trouble code (DTC).


Scanner plugged into OBD-II data link connector.
  • Tip: The OBD-II diagnostic trouble code (DTC) is a 5 character alphanumeric code. The first digit is a letter that indicates the component group, the second digit is OBD mandated or manufacturer specfic, the third digit is a subgroup, and the fourth and fifth digits define the component and basic problem.
  • 4. Locate the throttle position sensor.

  • Throttle position sensor

  • 5. Disconnect the electrical connector from the throttle position sensor.

  • Electrical connector removed
6. Test the resistance of the throttle position sensor (TPS) with a digital multi-meter. If the resistance is out of specifications, the TPS must be replaced.
  • 7. Remove the throttle position sensor.

  • d3a8007.jpg

    Removing sensor mounting screws

    8. Install the new throttle position sensor. Tighten the mounting screws and attach the electrical connector.
  • 9. Erase the diagnostic trouble code (DTC) with the scan tool using the“delete” or“erase” command. Road test your vehicle to see if the check engine light returns.

    Check engine light

  • Tip: If the check engine light returns, repeat the diagnostic process for additional DTCs or take your vehicle to a certified repair shop.
Direct OE replacement

Hope helped with this. Good luck (remember rated this help).

Nov 05, 2009 | Ford F-150 Cars & Trucks

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