Isuzu 3.1D Autoshifting problem

[baker123]

It can be adjusted, but what good will it do if the ECU is sending an in accurate voltage.

the TPS is the one sending the voltage not the ecu. the ecu reads the voltage. lets see. how do i put this.

the tps is the sensor. its like a switchable power adaptor. it can be 1.5v, 2v, 3v, 4v etc. if not set properly. the ecu will just read what the tps is giving and bases its fuel map to the sensor reading.

based on engines. if the ecu or sensor is at fault. then it should show CEL or something like that. and it would not run well.

but in the case of the 4v car. it runs fine. then it just means its not tuned right. or the tps is faulty. can be replaced/adjusted easily.

err sensya kung medyo mahaba. in my experiences with cars. i havent encountered broken ecu's except those that were tampered with. and usual problems are the sensors. hence the tps. if yun and not in spec.

[4JGtootsie]

the TPS is the one sending the voltage not the ecu. the ecu reads the voltage. lets see. how do i put this.

the tps is the sensor. its like a switchable power adaptor. it can be 1.5v, 2v, 3v, 4v etc. if not set properly. the ecu will just read what the tps is giving and bases its fuel map to the sensor reading.

But where does the TPS get its voltage? Battery? Alternator?

[baker123]

But where does the TPS get its voltage? Battery? Alternator?

now thats complicated. sorry. not sure about the answer.

could be thru the relays that also goes thru the ecu. then to the sensor. then back to the ecu.

[rion]

"TPS sends voltage to the ECU" it is not a perfect statement.

disconnect your TPS and you will still have a voltage reading in the ECU line.

The part of the ECU is the power supply... if you test the three wires.
in toyota's case, let's say Terminal 1 wire is positive ?volt, Terminal 2 wire is negative with 1Volt +(-)30% and Terminal 3 wire is negative 5volts +(-)30%

the TPS job is to send/share Terminal 3 voltage to Terminal 2. in full throttle, Terminal 2's voltage will be like Terminal 3's voltage.

if you disconnect your TPS, the ECU will just read Terminal 2 voltage, even in full throttle.

just like your Radio as your ECU. while TPS as your volume control. the technical name for volume control is actually called potentiometer (just like TPS).

Toyota Denso TPS:



just like a ordinary Volume control, it has three wires and a turning knob alike...

However, there is also a switch only and Switch/Potentiometer combination version. the pic above is a Potentiometer only version... I do not know what kind of TPS Trooper is using...

what the heck is Terminal 1 positive doing then? just like a ordinary old school volume control, if you put a opposite polarity on the other side of the terminal, it will make your potentiometer run it's resistance smoothly...



illustration 2 connection is mostly used on amplifier inputs with low power source. and TPS pala... but opposite polarity in Toyota's case. they use negative sourcing...

that's why it is important that we know that ltx's 5Volts terminal power supply source is ok. to do this is to unplug the TPS and measure the terminals from the ECU line.

[4JGtootsie]

Thank you Rion
Thank you Baker

Potentiometer and variable resistor is the important terms.
Angles and returning voltage based on the openning of the throttle.
The ECU supplies the voltage, the reason- so it can monitor more accurately since he is the one who sends and recieves voltage (minus minus) and for detection of failure of the sensor (DTC).

[baker123]

ayun mas galing mag explain.

thanks sa clarrification guys.

[rion]

Potentiometer and variable resistor is the important terms.
Angles and returning voltage based on the openning of the throttle.
The ECU supplies the voltage, the reason- so it can monitor more accurately since he is the one who sends and recieves voltage (minus minus) and for detection of failure of the sensor (DTC).

very well explained 4J!

here is my beautiful Art illustration work for the TPS (potentiometer type only)


hay, nakahiram ako ng digital tester at mali-mali yung readings ko sa una sa analog...

the opposite polarity will not just make the resistance run smoother when turned, but also deduct a little power from terminal 2. inside the TPS, there is a connection with big resistance between terminal 1 and terminal 2 (two different polarity)

meaning terminal 2 is 1.7 volts w/ unplugged TPS.

but when plugged TPS, it goes down to 0.7 volt.

hindi ko pala pa na exchange yung computer box , wala pa kasi yung isang vehicle...

[ltx]

Hello Guys,

My Problem is already solved. Below is my update during troubleshooting


Problem: No voltage measured from signal terminal of TPS
Doesn't have autoshifting during cruising


1st Day

Checked wiring, cleaned all metal in terminal connectors
Checked fuses...All are in good condition
Checked relays using portable adjustable DC power supply
[] ..... all relays are good

Checked Intake air sensor ..... good
Checkedd MAP sensor ........... good

[] Ignition ON and measure voltage at TPS .... 0.004V [No Voltage present]


2nd Day

[] request ni Erpat, i check ang solenoid sa transmission ..no choice erpat ang nag request e

[] Drain ATF of tranmission
[] Removed Oil pan, this will exposed Three solenoid of transmission
[] loosen each bolt that hold the solenoid, disconnect connector from solenoid, gently twist the solenoid and pull it out from solenoid body ass'y.

[] Checked the functionality of solenoid using portable DC pwer supply

[] Solenoid 1 ....good [plunger is working with power supply]
[] Solenoid 2 ....good
[] Solenoid 3 ....good

[] Reinstall 3 solenoid
[] eto mahirap, gumawa ulit kami ng oil pan seal, plus silicon
[] Install back oil pan
[] Fill in ATF... mahirap ulit, improvise kami maliit na imbudo


3rd Day.

[] sinundan namin wires from TPS going to controller [module or computer box]

[] ooops ... ito palang Bighorn ay tatlo ang Module box..akala ko isa lang

[] Ang gulo ng wiring, at masikip ang loob ng dash board , kaya tiis tiis na lang kami..
[] ...sa WAKAS!!! nakita namin kung saan papunta yung wires .. dun pumunta sa module EGR 12V located sa ilalim ng dash board sa likod ng shifting stick.

[] Volatge measurement ulit.. measure voltage at control box and compare it sa end terminal ng TPS......Parehong walang reading, as in no power

[] Checked supply volatge of Controller box * ignition ON ....Ok 12V
[] removed controller [EGR 12V] from Bhorn
[] Disassemble controller and checked electronics device and PCB.
...walang sunog, pero puros cold solder na ang mga terminal

[] resolder all pcb terminal of controller.

4th day

[] Install back controller EGR 12V to Bhorn
[] Testing ulit , Ignition ON...measure voltage at TPS.....damn!! ganun pa din problem, walang voltage

[] No choise ..... punta kami Banaue, kay Walco .... malas walang available na controller.. ...mukhang malabo ng magawa.

since pauwi na kami, hinanap na din namin si Baltak, tipong para malaman namin ang location nya lang.

we found out na surplus,and spare parts supplier din pala si Baltak

tanong kami kung may controller na ER 12V ....oooppss meron sila.

[] Try namin muna ... kabit ng controller from baltak .... YES!!! gumana.

It cost me P14,000.00 for that magic box...pero Okay lang



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Thanks ulit sa mga nag share ng opinions, suggestions, and advice.

God bless you all...

[4JGtootsie]

Congratulations on a job well done. Ang sipag mo pala magcheck ng electricals. Sa EFI ganyan talaga relays,actuators,sensors, ECU, CB, thermistor, potentiometer, solenoids, valves. If you have the patience and a VOM, you can be a one man business. Mass ok kung meron kang diagnostic tool.

[nap123]

Ayus

[4JGtootsie]

Mods,

Arborin na po namin itong thread. Palagay na lang sa sticky ng Isuzu Clubs.
Para naman manuwari mabuhay ang samahan IVEA or IMG.

[ltx]

Sir 4jgtootsie, meron ba kong maitutulong para mailipat ang thread sa Isuzu club? allowed ba ako sir?... sana mailipat nga

[4JGtootsie]

LTX,

Paki request sa moderator na ilipat sa isuzu club sticky para madling mahanap. Ikaw yata kailangan mag request kasi ikaw ang thread starter.

[bigcawa]

Up natin para hindi matabunan. Very usefull ang thread na ito para sa mga Bighorn owners

[4JGtootsie]

Sir Garyq,

Pa sticky po sana namin ito sa Isuzu Clubs for quick reference ng mga isuzu peeps. More power and thank you!

[batosai]

Mga sir up ko lng.. find this thread verry useful for those bighorn user out there

[Frank-knarF]

mga Sir up ko lang,san shop po kaya pwedeng magpa-adjust ng TPS ng Terrano TD27 turbo (subic)?
mabilis po kasi shifting wala pa pong 50kph ubos na upshift kaya hanggang 70kp/h lang po max speed ko kasi galit na po ang makina. Mahina din po ang hatak sa uphil.Before ko po ipaayos sa casa, i need your suggestions muna kung meron kayon alam na shop/s na trusted at magaling.TIA