Hello,
I have a 1987 TA with a 305 TPI motor
I have a low voltage problem with the TPS sensor.
I can only adjust the orignal one to 0.05 volts, and the book that I have says that I need 0.47 to 0.61 volts. I had the volt meter checked and it is working correctly. So I bought a new TPS and could only adjust it to 0.06 volts still not good. So the parts store is going to get me another one. Is there anything else I should check? I am new to TPI motors. Thanks in advance for your time
LAter and

GB

Rick king

 

Measure the voltage at grey(or white) wire at the TPS. It should be 5 volts with TPS connected or not. This is a reference voltage from ECM.

Dark blue wire should change approx. from 0.5V to 4.5V when changing throttle from fully closed to wide open. It should be measured with the TPS connected to the harness. To do so you might need to splice the blue wire or insert really thin wire in the TPS connector.

Black wire is ground.

 

first time volt meter user here...could you please tell me what to set my multimeter on in order to test my TPS voltage. I have a shop manual and know how to place the jumper wires but i'm not sure how to use the multimeter...I know this sounds elementary but i have owned a carbed '86 for the last 9 years...I just bought this '89 iroc, 305 TPI, about 2 months ago...I have replaced the IAC and TPS and just realized the problem was my MAF...I want to properly set my TPS voltage, though, before I install my MAF...Thanks

 

Hello,
you will do just fine. I wqould recomend a digital muti meter. there is a book that comes with them that explains then. You just have to select the proper setting. The new ones are pretty stright up. Start by testing your battery or a wall out let, or the resistasnce of a sparkplug wire. This will help you get use to the different settings according to the book.
later and
GB

rickking

 

Ok
the new sensor gave the same readings 0.06 volts max adjustment. Pretty low. I checked the grey wire and I have 4.98 volts at it. if i remember right the code was #13 anyway it was the one that said low voltage for TPS sensor. any futher help will be appricated. Last time it ran it stumbled all over the placefrom 500 rpm to 1800rpm and i had to feather the throttle. Also I double checked the timming it is ok. I rechecked the vacume lines and they are according to the diagrams from 2 different sources
thanks in advance
later
and
GB

rick king

 

Does it change when you open the throttel?
And you do have to have it connected to the harness when measuring.

 

Yes
I checked it today and the reading would go from 0.06 volts with the throttle closed to 0.24 volts with the throttle at wide open.

thanks


rick king

 

I forgot to mention the harness was hooked up when I did the test
thanks again

rick king

 

Code 13= Oxygen Sensor Circuit (open circuit)

Code 21= Throttle Position(TPS) Sensor Circuit (Signal Voltage High)

Code 22= Throttle Position(TPS) Sensor Circuit (Signal Voltage Low)

If you measured voltage between pin "A" (black wire) & pin "C" (grey wire) and got 4.98 volts, that is good. Pin "A" is the ground and pin "C" is the ECM Signal wire. Pin "B" (dark blue wire) is the positive wire. If you are only getting .06 volts max measuring between pin "A" & pin "B". I would start backtracking the wire harness for a bad wire or ECM. BTW, just out of curiousity. How are you trying to adjust the TPS. Is it by having the two attachment screws loosened slightly and moving the TPS to get the right voltage and then tightening the screws?

 

yes I was adjusting the TPS the way you described. I will go and back track the harness and let you know what I find.
thanks
rick king

 

OK
this is what I have found. I double checked the diao trouble codes and I could only get the #12 code this time wich is the speed referance plus according to my book.The book I am using is a Chilton. Also I did remove the air pump from the emmisions. On the passanger side of the motor I found a none conecteed black wire. This wire had a conector on it with a rubber back for a plug in. According to the diagram I have i believe that it goes to the knok sensor, but I can't make heads or tails of the wireing diagram my book has!!
HELP

thanks and
GB

rickking

 

A single black wire on the passenger side down near the starter is the fan switch located between cylinder #6 & #8. Single white wire in that same area is knock sensor located just forward of the starter.

 

cool thanks

it stoped raining so I will go hook it up. Also could that be why the fan kicked on while checking the codes?. now if I could just get it to run smooth and consitant.

it is all over the place, and I still have low volts to the tps. The car was a theft recovery and the steering collum is punched and chiped maybe when the new collun is it it may clear up. I can't figure out why that would make a differance sience it ran fine befoe

what should I look at now?

still lost

thanks

rick king

 

OK
the fan wire is still disconected because the fans are hotwired because the car is a theft recovery
thanks
rick

 

i have a Code 22: Throttle Position Sensor/TPS voltage low what could be causing it to come back?