Jor2010dan

Hey I was driving on the freeway and Put my cruise control on and it was super irradic. I pulled the codes 12-24-55. So my Tps is reading too high. Replaced it about 3 months ago. Any ideas?? Need to get on the road to my moms for mommies day!

Gee oh Dee

I've heard someone mention calibrating it, but never saw what came of it. (TPS)

tjwalker

On 91-01, the throttle position sensor is not adjustable.

Let's go back a bit. Why did you replace your TPS three months ago? Was it throwing the same code then??

You CAN test your TPS. And if you are throwing a code for the TPS, testing is job #1. Verify connector is good and a spray of electronic contact cleaner into the connector is never a bad idea. Verify all TPS wiring.
-----------------------------------------------

The throttle position sensor is connected to the throttle shaft on the throttle body. It sends throttle valve angle information to the PCM. The PCM uses this information to determine how much fuel the engine needs. The TPS is really just a simple potentiometer with one end connected to 5 volts from the PCM and the other to ground. A third wire is connected to the PCM. As you move the accelerator pedal with your foot, the output of the TPS changes. At a closed throttle position, the output of the TPS is low, about a half a volt. As the throttle valve opens, the output increases so that, at wide open throttle, the output voltage should be above 3.9 volts. Testing can be performed with an electrical meter. Analog meter is best. You are looking for a smooth sweep of voltage throughout the entire throttle band. While slowly opening and closing the throttle, take note to the movement of the voltmeter needle. There should be a direct relationship between the needle motion to the motion of the throttle. If at anytime the needle moves abruptly or inconsistently with the movement of the throttle, the TPS is bad

You should have 5 volts going into the TPS. At idle, TPS output voltage must be greater than 200 millivolts. At wide open throttle (WOT), TPS output voltage must be less than 4.8 volts.. The best is to use an analog meter (not digital) to see if the transition from idle to WOT is smooth with no dead spots. With your meter set for volts, put the black probe on a good ground like your negative battery terminal. With the key on, engine not running, test with the red probe of your meter (install a paper clip into the back of the plug of the TPS) to see which wire has the 5 volts. One of the other wires should show .26V (or so). The other wire will be the ground and should show no voltage. Move the throttle and look for smooth meter response up to the 4.49 at WOT.

Perform the test procedure again and wiggle and/or tap on the TPS while you watch the meter. If you notice any flat spots or abrupt changes in the meter readings, replace the TPS.

The TPS is sensitive to heat, moisture and vibration leading to the failure of some units. The sensor is a sealed unit and cannot be repaired only replaced. A TPS may fail gradually leading to a number of symptoms which can include one or more of the following: -

NOTE: The throttle position sensor is also DIRECTLY involved with transmission shifting characteristics! It should be verified early in the troubleshooting process, when a transmission issue is suspected!

• Poor idle control: The TPS is used by the ECU to determine if the throttle is closed and the car should be using the Idle Air Control Valve exclusively for idle control. A fault TPS sensor can confuse the ECU causing the idle to be erratic or "hunting".
• High Idle Speed: The TPS may report faulty values causing the engine idle speed to be increased above normal. This is normally found in conjunction with a slow engine return to idle speed symptom.
• Slow engine return to idle: A failing TPS can report the minimum throttle position values incorrectly which can stop the engine entering idle mode when the throttle is closed. Normally when the throttle is closed the engine fuel injectors will be deactivated until a defined engine RPM speed is reached and the engine brought smoothly to idle speed. When failing a TPS will not report the throttle closed and fueling will continue causing the engine to return to idle very slowly.
• Engine Hesitation on Throttle Application: The TPS is also used by the ECU to determine if the driver has applied the throttle quicker than the Manifold Air Pressure sensor can read. The fueling is adjusted acordingly to cope with the sudden increase in air volume, however a faulty sensor can cause the ECU to ignore this data and the engine will "hesitate" when applying the throttle. In extreme cases with the engine at idle, a sudden application of full throttle can stall the engine.
• Engine Misfire: A fault TPS can report values outside the deined acceptable range causing the ECU to incorrectly fuel the engine. This is noticable as a slight misfire and can trigger the misfire detection software and/or Malfunction Indicator Lamp (MIL) light on the dashboard. Extreme cases can cause excessing misfires resulting in one or more cylinders being shut down to prevent engine and catalytic converter damage.

Gee oh Dee

Ha, funny. Go figure I've got an 87.

Jor2010dan

Well it sounds like mine is bad. I replaced it when it was causing weird idle symptoms. Now its bad. This is actually the first time its been on the freeway. I'm currently traveling. At the 65-75 MPH range my speedometer becomes wayyy irradic. Like it goes up to 90-110 and flickers. Cruise control is unuseable. And if it down shift at 60-75 it feels like its misfiring. Any ideas? I'm lost and stuck on what I should do

Gee oh Dee

TPS and speedo have no relation iirc...

tjwalker

Test your throttle position sensor. I've provided you with test procedure.

Follow the lead of your OBD code as job #1, as you must resolve that first, and then see where you are at.

It's possible that you have more than one problem here.......

Jor2010dan

Well it sounds like mine is bad. I replaced it when it was causing weird idle symptoms. Now its bad. This is actually the first time its been on the freeway. I'm currently traveling. At the 65-75 MPH range my speedometer becomes wayyy irradic. Like it goes up to 90-110 and flickers. Cruise control is unuseable. And if it down shift at 60-75 it feels like its misfiring. Any ideas? I'm lost and stuck on what I should do

Jor2010dan

I'm away from my meter. Do I just buy a new tPS?

Jor2010dan

K so I bought a meter. Tested with Jeep off key on. 5v. On one. .5v. And 0v. With.It started. It reads 5v. .5v (when I touch this one engine slows idle) when opening throttle 5v. .5 v. If I'm in the. 5 one that isslowing my idle at WOT IT doesn't change. Then when off throttle it kills the engine. So is my wire or pcm bad??

Jor2010dan

Here's a vid of my speedometer. When it hits 3000 rpms it misfires.
http://www.youtube.com/watch?v=http:...?v=-Z4YLlIXnjk

1991Jeep_Man

Lol, Im sorry but I had a good chuckle at that vid. You'd think the damn thing is posessed or something. BEGONE EVIL SPIRIT! Better break out the Holy Oil.

All jokes aside, I don't see how the TPS will have a connection with that whacked out speedo problem. The TPS, IIRC, simply gives a signal to the PCM to adjust fuel input accordingly to throttle position, and also sends a signal to the TCU for shifting. I may be wrong.

Jor2010dan

after the 2 hours to vegas, messing around at autozone for an hour, deciding the drive wasn't worth it, I limped it back home.

New TPS. Still doesn't register right on the TPS output wire. It stays at .5

But anyways, dinked around with the speed sensor on the transfercase when I got home. The pigtail was unplugged and the unit was twisted weird.
After plugging the pigtail in better and trying a couple different angles on the speed sensor, got it to where it runs fine now. Took it on the free way, no more misfiring. Cruise works again. Speedo sits still.
What a waste of a day. Not to mention 40$ Volt meter 40$TPS. Driving 3 hours isn't cheap either. ****ing jeeps unreliable as hell.

excess650

VSS on the output shaft is also related to AW4 shifting and cruise control as you found out. If you had to move the connectore wires to various positions for it to work, you still have a problem. Most likely its a broken wire.

I just replaced my VSS (1996) and the replacement had a different connector and pigtail supplied. What should have been a 5 minute job took much longer because of cutting, splicing, soldering, heatshrink, and retaping.....PITA when working on your back.

Check the ground wire on your TPS to the engine block or at least the firewall ground to see if there is a difference; ie, check the 5v to the ground wire in the TPS plug and then against the engine block ground or battery post and see if there is a difference. If you see 5.1v against the battery post and 4.6v against the TPS connector ground, you've found your problem. BTW, test the TPS output with the ignition ON, but engine NOT running.

paulhead

Could the jeep sitting for a year cause the TPS/comptuer to need to be re calibrated ie driven around for a while?