angelsman

Driving to work this morning, went thru town, gave the truck some gas, engine light came on and then rpms started to climb. Was runnin good up until then. Could it be the governor? Fluid is clean and pink, was only 60° and raining out and engine temp was normal so I wouldn't think it overheated. Any suggestions?

angelsman

Its a 99 with 185k on it. Trans has always been strong, never slipped, don't tow with it, kust work and wheelin.

Slick761

Did you check the fluid?

angelsman

Fluid good and full. No slippage, just won't shift out of first gear.

tjwalker

Throttle position sensor is primary suspect. It is directly involved with shifting characteristics. More below.
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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.

excess650

It sounds electrical, but you can make a quick test to prove or disprove that. Pull the TCU fuse from the power distribution box under the hood OR unplug the TCU. The trans should shift manually with R getting R, 1-2 getting 1st, 3 getting 3 and D getting 4th (.75 OD). If it shifts that way its electrical.

TCU, TPS, VSS, brake pedal switch (inhibits lockup) and NSS are all possibilities.

angelsman

Thanks guys, it was the TPS! Vents in hood are not good for electrical stuff.

tjwalker

You are very welcome. If the TPS gets wet, it doesn't play well with others.

Glad it was an easy (and cheap) fix.

angelsman

Except ........I put the new one on and it won't idle down past 1200 rpms. Its the third tps, the first had a catch in it that would not let it idle down. This one is free and clear, rotates nicely. Maybe the comp. needs to get used to it?

Mrjw1996

i think you have to reset the system by disconnecting the battery when you install stuff like that but im not too sure

angelsman

Drove to work. Workin better now.

6bangersj

Did you buy a new tps or did you take it out and clean it? Also did you cover that part of the vent up or left it open? I just put hood vents in and my tranny started acting up wouldn't shift out of first high idle at start up. I have a 89 with 215k I out a new tps and adjusted it couple months back before the hood vents drove great then.

DCWinterXJ

I had the same exact problem and stupidly kept re-adjusting the throttle valve control cable(TVC) Cruiser54 and tjwalker called it first shot with the TPS! Instantly got my transmission back. However I didn't have your high idle problem so I never reset the sensors/pulled the battery cable for a while. Anyway the guys on this forum are awesome!

DCWinterXJ

Wow this thread is 8 years old! Dang I knew something was off when I saw the amount of reads...oh well still good advice haha