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Discussion Starter · #1 ·
so ive been having problems and I found that the signal wire from my tps (orange/blue) is getting like 4.58 volts and the power wire (violet/white) is getting its proper 5.0 volts.

working on tracing it back but this is pissing me off.

If anyone has had this problem before that would be cool to know about.

that signal wire should be zero when not plugged in to the tps connector right?
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I just traced it back to the engine bay harness so its a problem before the engine harness. I got 4.58 volts @ the grey 10 wire connector.
 

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First, What are we working on? The 94 Spirit 3.0?
Is there a Fault Code Set?
 

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Discussion Starter · #3 ·
94 3.0 spirit sbec

tps code.

I was having some problems before (and had a friends OTC scanner to look at it) but it was apparent that the voltage was too low (bad connection etc).

Now the problem is that my TPS is acting like its not even plugged in. I can plug it in/out and it behaves the same.
I can tell the ECU is using the MAP sensor to guess what the TPS position is.

on my car the orange blue wire goes to the ECU as the signal ground and it also goes to the a604 trans computer (no longer auto as of 5 years ago) to tell the transmission to downshift when tps voltage is high.


What I need to find out is where this 4.58 volts of power is coming from in the signal wire (even when its detached from the tps sensor). I have come male/female connectors on the tps sensor pigtail so thats why im not worried about it being apart.

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my current idea is to cut the orange/blue tps signal ground wire near the ECU and see if the power is coming from the ECU.
That would NOT solve anything for me though because i tried 3 ECU's and all of them behaved as if the TPS sensor did not exist. Im just guessing because the signal voltage is 4.58v which is much higher the the chrysler tps maximum signal.

I am trying to work on my race car but this is really bothering me because the car is really not drivable (well you can drive but it sucks).

I have tried different sensors, a whole different engine harness.

I have isolated the problem to the engine bay harness (unplug engine harness and no voltage in the engine harness wire but still voltage on the engine bay harness end) or the ECU (assuming all 3 of my ecu's have this problem)
 

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Discussion Starter · #4 ·
Yeah so I feel pretty stupid now.

I did cut the wire and the ecu is ending 5 volts into that wire.
I also checked out my other 3.0 car (1992) and the same thing.

I guess Im really confused now.

I understand why the violet/white wire is 5.0 volts because its the power wire for the TPS and map sensor.

I dont understand why the signal wire is 4.58 volts. I have done this before and never had weird stuff like this happening.
 

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Lets start at the beginning. I need more detailed info to help with diagnostics.
What was the driveability concern that led you to check the TPS Circuit?
Was the Check Engine Light On?
Were any Fault Codes Set? (other than the ones that may have been set by
diagnostics)
What was the TPS Voltage with Key ON/Engine Off?
Did you Sweep the TPS to see how it responded?
 

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Discussion Starter · #6 ·
Ondonti said:
94 3.0 spirit sbec

tps code.
code 24
check engine light on.

No other fault codes set

key on/ engien off, orange/blue reads 4.58 volts
violet/white reads 5.01ish since its the power wire
Reads the same voltage @ the engine bay harness with the engine harness unplugged.

drivability problem is that there is no throttle response.
Car drives exactly the same if you unplug the TPS sensor.
I can tell the car is using the MAP sensor voltage to estimate Throttle position.
Let off the gas and rpms drop and sometimes the engine dies if I am not careful because the ECU has no idea that I let off the gas (TPS signal needed for engine to know that).
So because of this its dumping way to much fuel because as far as I know, when you have no TPS signal the car estimates TPS using the MAP as a limp home mode and there is basically light throttle and WOT estimations so the car is dumping way to much fuel at medium throttle.
 

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I will get back to you on this but I would like to know what the Scanner was showing for TPS Voltage.
 

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5Volts on Violet is good. Blk / Lt Blu should show ground potential. Org / Dk Blue should read close to 0 volts with the TPS closed and the voltage should rise smoothly up to close to 5 volts as you gently open the throttle. Seeing 4.58 volts on the signal wire (org / blu) will make the computer think your WOT all the time. Sounds like a bad TPS or the wiring is wrong.
 

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Discussion Starter · #9 ·
87turbodance said:
5Volts on Violet is good. Blk / Lt Blu should show ground potential. Org / Dk Blue should read close to 0 volts with the TPS closed and the voltage should rise smoothly up to close to 5 volts as you gently open the throttle. Seeing 4.58 volts on the signal wire (org / blu) will make the computer think your WOT all the time. Sounds like a bad TPS or the wiring is wrong.

not a bad TPS.

I get 4.58 volts on the enbine bay harness.

I even cut the orange/blue wire near the computer and got 4.58 volts.....and its coming from the ecu.

I tried 4 different ecu's and even tried my other car and now both are doing it.

I dont know whats going on........
 

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Since you have access to a Scanner you need to read TPS Voltage thru the Scanner so you can see what the Controller is seeing.Code 24 is TPS Voltage High or Low,only the Scanner will differentiate between the two.
My son is bringing me his 1994 Chrysler 3.0L Powertrain Diagnostics Manual tonight so I can lead you thru an organized diagnostic procedure,but since this is a Chrysler Manual you will probably need a Scanner.
 

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when you say you are getting your 4+v on the signal wire, is that from the ECU to ground or TPS to ground? almost sounds as if something on the board died or shorted and is dumping voltage into the TPS circuitry. did you try a continuity test on the signal wire? signal wire to ground and signal at ECU and at TPS? if your getting continuity from the TPS signal wire to ground or TPS to your +5v source you have a short somewhere.
 

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Discussion Starter · #12 ·
i said I cut the wire near the ecu and the 4.58 volts is coming from the ecu

so apparently I fried 4 ecu's or I instantly fry every ecu I try on this car........or???


the codes I ran before were TPS to high and TPS to low.
 

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thats messed up. no idea then.....:(
 

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Still waiting for Tps Voltage Reading from Scanner with Key On/Engine Off and Throttle Closed.
In the Future Do Not Cut Wires to check Voltage. You can purchase a Set of Test Leads for your DVOM that have a Wire Piercing Pin built in which is not recommended because you leave openings for Moisture to enter.
The Prefered Method is to "Back Probe" the Connector,you can purchase Backprobe Pins made just for this or use a Paper Clip, just be sure you are making good contact with the Terminal.
When you repair your Cut Wire DO NOT use Solderless Butt Connectors. You will have to Solder and Seal with Heatshrink with an Anti-Moisture Gel to Seal the Connection and keep Moisture Out. You can purchase this Heatshrink at any Chrysler, Dodge, Jeep Dealer.
You have to be sure you have a Tight , Secure, Weatherproof Connection,the Controller is Reading Millivolts and any change in the Resistance of the Wire will change the Voltage the Controller is seeing.
 

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Discussion Starter · #17 ·
the voltage used to be .70ish volts key on engine on. Never tried with it off. That was on the scanner.

I had to cut the wire otherwise i wouldnt be able to isolate the voltage.

This proved it was not coming from a short circut someplace else.
The scanner is currenty an hour drive away :(
 

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My Son could not find the 94 Book so here are Diagnostics from a 92 Book,Hope the Wire Colors and Controller Terminals are the same,I was told they are. You have to be sure that the Code is TPS Voltage Low.
Code 24 Diagnostics, TPS Voltage Low.
Ignition Key Off, Disconnect TPS Connector,Turn Key On
With your Voltmeter Probe the VT/WT Wire,is the Voltage below 1.0 Volts?
YES, Repair the Open VT/WT Wire
NO, Probe the OR/DB Wire, is the Voltage below 1.0 Volt?
NO, Replace the Throttle Position Sensor
YES,Ignition Key Off, Disconnect Engine Controller
With your Ohmmeter probe the OR/DB Wire to Wire Cavity #22
Is the Resistance below 10 Ohms?
YES, Repair the OR/DB Wire for a Short to Ground.
NO, Replace the Engine Controller
 

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Discussion Starter · #19 ·
Well the problem I have is that the 4.58 voltage to the OR/DB wire is above 1.0 but the voltage is not coming from the TPS.

I understand most of the help but it seems like no one is reading what I am posting.
I cut the wire off of pin #22 and the voltage is coming from the controller with the key on engine off.


and replacing the engine controller does not seem like a good idea because I seem to create this problem on any ECU I install. I used to have 4 ECUs.

So if the ECU really is the problem, I need to find out what is killling the ECUs :(
 
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