TPS Problem I had a TPS code at the mechanic. The mechanic put in a new TPS and the problem stayed the same. I put in a new ECU and the problem stayed the same. I'm playing mechanic myself now and here is what I have. I disconnected the TPS connector and tested the power at 5v, the reference at 4.7v, and the ground wire is fine. I believe the reference voltage is only supposed to be .5v , but I don't know anything about this stuff. The reference wire is giving me a reading for wide open throttle when it isn't connected to the tps. Should I be getting .5 with it disconnected on the ref wire? I've already tried 2 ECU and the voltage stays the same. Could a bad wire give me more voltage??

Code 78 APPS Main and Code 79 TPS Main are diagnostic trouble codes (DTCs) that can appear on a 1997 Mitsubishi Pajero. Code 78 APPS Main: This code indicates that the APPS (Air Pump System) Main relay is not working properly. The APPS relay is responsible for supplying power to the air pump, which is used to control the air-fuel mixture. Code 79 TPS Main: This code indicates that the TPS (Throttle Position Sensor) Main circuit is not working properly. The TPS sensor is responsible for sending information to the engine control unit (ECU) about the position of the throttle valve. If either of these codes appears, it is important to have the vehicle diagnosed by a qualified mechanic to determine the cause of the problem. The mechanic may need to test the APPS relay, the TPS sensor, or other components in the fuel system. Here are some possible causes of Code 78 APPS Main and Code 79 TPS Main: Faulty APPS relay: The APPS relay may be faulty and not be supplying power to the air pump properly. Faulty TPS sensor: The TPS sensor may be faulty and not be sending accurate information to the ECU about the position of the throttle valve. Clogged air filter: A clogged air filter can restrict airflow to the engine and cause the APPS relay to overheat and malfunction. Low fuel pressure: Low fuel pressure can cause the APPS relay to overheat and malfunction. Faulty wiring: The wiring to the APPS relay or TPS sensor may be damaged or corroded, causing the codes to appear. If you are experiencing problems with your 1997 Mitsubishi Pajero and either Code 78 APPS Main or Code 79 TPS Main appears, it is important to have the vehicle diagnosed by a qualified mechanic to determine the cause of the problem and to get it repaired as soon as possible.

didnt specify vehicle --generic answer--until repair is made the vehicle will show engine light and have codes --if gearbox is problem for limp mode /until repairs are made or gearbox replaced you will be in limp mode --and as to sensor find out what one it was --start problem may show back up if sensor was problem --and GET a 3rd opinion you have 2 mechanics with different opinions on your problem and i guess they are reading your trouble codes differently

i had the same car.... what mileage.... 200K?
TPS errors. (its real its a real measured error)
this error is catastrophic, , meaning, not just a tad off,
the FSM covers this in details.
clock spring, the Air bag clock spring? has nothing to do with this.
or do you meant the throttle return spring, (my guess?)
the TPS output pin was discovered to have an illegal high voltage
on the output (you can be sure it idid)
spec:
TP Sensor indicated more than 4.50v for 700 ms.

caused by a bad TPS ground wire, or the output pin cut.
or the TPS internals are cracked in half (bad inside) (i have photos)
its bad TPS or bad wires to it. simple huh?
it will not be a bad ECU. as is on the list; it will not.
The jeep has great cheap TPS to buy ofter market,
on other cars not, and can cost $300 , for them
i connect my potable scope and watch the TPS output while i drive.
and find out if it is really truly bad.... hell the part, costs more than my
scope.!
be happy its not new car with throttle by wire, !!!
or the big V8 , whole new throttle body for $1000

recap. bad TPS, bad wires.

the tps on most cars are calibrated.
if you just thrown on a new TPS and not calibrate it, that is
a big failure.
here are the steps
1 key off
2 remove TPS.
3: put back new.
4:
The TPS is mounted to the throttle body. The throttle shaft end of throttle body slides into a socket in the TPS. The TPS must be installed so that it can be rotated a few degrees. (If sensor will not rotate, install sensor with throttle shaft on other side of socket tangs). The TPS will be under slight tension when rotated.

1. Install TPS and retaining screws.
2. Tighten screws to 7 Nm (60 inch lbs.) torque.
3. Connect TPS electrical connector to TPS.
4. Manually operate throttle (by hand) to check for any TPS binding before starting engine.

adjust the TPS for
0.26 volts at minimum throttle opening (idle)

worst case:
the FSM says it auto calibates
if the new TPS errors,. set it to 1/4 volt at idle.
reset ECU , all DCTs using scan tool
pull battery for 5min neg. lug (backup radio codes first)
put back lug
start engine, drive 25miles or till CEL comes on (failures)

I had a similar problem with my 280 Datsun. It turned out to be the fuel pressure sensor located near the fuel injectors. Some of them come with a vacuum hose attached.

yes and you will need to take it somewhere to have the ECU be reset. Example: windows, TPS sensor, etc.

Strange that it failed the emission test. The codes given relate to the transmission computer not outputting the correct signals to the engine (power) control module ECU. Have you noticed any abrupt gear shifts lately? I wonder if the emission test failure is related. Sometimes the gear selection failure can be as result of the ECU getting the incorrect information from a faulty throttle position sensor TPS. The ECU relays the information to the transmission controller and this snatches at the gear shift at slightly the wrong time. A faulty TPS might also be responsible for the ECU setting the wrong fuel air mixture and this would result in inappropriate exhaust gas emission. The TPS is on the throttle plate shaft and is located on the outside of the throttle body. The two outer pins on the TPS plug have 0 volts and 5 volts. The middle pin sends the voltage to the ECU according to the throttle shaft position between 0 to 5 volts. Check out the TPS thoroughly before looking for something more complicated. Then next I would pull the sockets from the respective control units and make sure all the contact pins are clean and bright to ensure good inter connection

I am having the exact same problem with my 2001 Hyundai Elantra. I was told that the engine code that comes up when the sensor is on is called "Absolute Pressure In The Manifold". I was told by a "Hyundai Specialist" that when that code comes up it usually means that the seal on the manifold is Fuct. When my mechanic checked that out for me he had noticed that my manifold had 4 cracks in it(can varify cause he showed me). He replaced the manifold and gasket. The car ran fine for about 2-3 days and since then the problem has since come back and my check engine light will no longer go on/off it only stays on. Because of the check engine light always staying on I have noticed that on many occasions my car will hiccup many times in a row. The only way to stop the hiccup I have noticed is to take my foot right of the gas for approx. 2-3 sec then car will continue without hiccup(till it happends all over again). All in all I have been having this problem now for approx. 1 year and if there is somehow someway it could be repaired I would appretiate it.

Did the 'Check Engine' Light come ON? Whenever the 'CHECK ENGINE' light comes on, the ECU (Engine Control Unit) sets a Diagnostic Trouble Code (DTC). These codes identify the particular engine management system which caused the light to come on. You'll need to use/find an OBDII (On-Board Diagnostic) Scanner to retrieve any code which have been stored in the ECU computer. Afterward, we might be able to help you DIAGNOSE and perhaps eventually fix the problem.
NOTE: Commonly, the throttle position sensor (TPS)can cause the symptom you describe without turning on the CHECK ENGINE light. The TPS is a simple dash-pot (potentiometer) which can develop problems with age/time. Recommend you find a mechanic/ electrician who knows how to test it for bad spots -- if they find any, replace it.

bad computer. had the same problem sent mine to auto computer exchange in Davie Fl. they reprogramed it . The problem is gone.

try putting your vehicle on a diagnostic check although you have changed the alternator the ECU ( car computer ) may still think that the alternator is still faulty a diagnostic check will cure your problem by clearing the fault codes on your ECU

dean