Wire colors and voltage?

Tiny
GOONIEFREAK76
  • MEMBER
  • 2005 DODGE RAM
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 225,000 MILES
I have written to you about my truck before. Long story is it hasn’t run right since I have had it. I started out replacing the fuel pump, replaced the gas pedal position senser, the throttle body, and a few other sensers. My next step that I can figure out is it maybe the PCM, but I don’t want to throw money at it unless I can get it going. So, I want to check to see what the voltage going to the PCM and what is coming out, the voltage at the throttle body and gas pedal position senser. Can you tell me the colors of the wires I need to check and the voltages at each.
Tuesday, October 29th, 2024 AT 7:45 AM

10 Replies

Tiny
AL514
  • MECHANIC
  • 4,691 POSTS
Are you getting any codes setting in the PCM? And is it a crank, no start right now? I'll pull up the wiring diagrams for you on those sensors.
Was this
answer
helpful?
Yes
No
Tuesday, October 29th, 2024 AT 11:49 AM
Tiny
AL514
  • MECHANIC
  • 4,691 POSTS
And is the 8th digit of your VIN# a "D"?
Was this
answer
helpful?
Yes
No
Tuesday, October 29th, 2024 AT 11:51 AM
Tiny
AL514
  • MECHANIC
  • 4,691 POSTS
This is the wiring diagrams and pinout for the Throttle position sensor that is on the throttle body, I don't know if the pin numbers in the 3rd diagram is correct, so you will have to go by the wire colors, I will post the APP sensor diagrams next.
Was this
answer
helpful?
Yes
No
+1
Tuesday, October 29th, 2024 AT 1:02 PM
Tiny
AL514
  • MECHANIC
  • 4,691 POSTS
Here's the Accelerator Pedal Position sensor wiring and connector pinout.
Was this
answer
helpful?
Yes
No
Tuesday, October 29th, 2024 AT 1:03 PM
Tiny
GOONIEFREAK76
  • MEMBER
  • 15 POSTS
Thank you for getting back so soon, I wasn't expecting something so quick. What I have is it starts and ideals but nothing else. Nothing on the gas pedal. I have looked several to hundred different times to try and narrow it down but every time I look I get a different answer of what it can be. I have read the codes several time as well and the only thing I keep getting it something about a 2nd sensor on one the exhaust. Yes the 8th digit is a D. Also, it will be about a week and half to get back to you on what the wiring voltage will be. I am 20 hours away right at the moment.
Was this
answer
helpful?
Yes
No
Tuesday, October 29th, 2024 AT 2:27 PM
Tiny
AL514
  • MECHANIC
  • 4,691 POSTS
Okay, no problem. So you're only getting a code for one of the oxygen sensors in the exhaust pipe. No APP or throttle related codes at all?
Was this
answer
helpful?
Yes
No
Tuesday, October 29th, 2024 AT 2:32 PM
Tiny
AL514
  • MECHANIC
  • 4,691 POSTS
Its a drive by wire system, meaning the gas pedal sends an electrical signal to the engine computer (PCM) tell is the pedal is being pushed down, and then the computer will open and close the throttle plates accordingly. So there should be other codes setting, the APP sensor has 2 signals it sends to the PCM that should match each other, plus in almost every modern vehicle all these wires are monitored for shorts to ground, shorts to power, or open circuits, and if both signal wires from the APP sensor were open circuit, it would set a code for that, so there might be something else going on here.
Was this
answer
helpful?
Yes
No
Tuesday, October 29th, 2024 AT 2:38 PM
Tiny
GOONIEFREAK76
  • MEMBER
  • 15 POSTS
So, once I check the voltage I should know if everything is working right, or I may have a short or open. Is that what you are saying, or did I not understand right?
Was this
answer
helpful?
Yes
No
Tuesday, October 29th, 2024 AT 2:43 PM
Tiny
GOONIEFREAK76
  • MEMBER
  • 15 POSTS
No other codes.
Was this
answer
helpful?
Yes
No
Tuesday, October 29th, 2024 AT 2:49 PM
Tiny
AL514
  • MECHANIC
  • 4,691 POSTS
The APP sensor is listed to be under the battery on the aftermarket wiring diagram, which is not correct. It is on the pedal, But with the Key On, engine off, there should be two wires with 5volts on them, two wires which are Grounds for the sensor, and if you back probe the signal wires while the connector is still plugged in, checking one signal at a time, you should see the voltage fluctuate from 0volts to roughly 5volts when you press the gas pedal down, usually it's not all the way to 5volts, some only go to 3volts, some 4.5volts, etc, but it should change with pedal movement, You can use the sensors Grounds (APPS RETURN) or Battery Negative when testing with a multimeter, I would check using both ground locations to see if that's possibly the issue.
With no codes, there is definitely some other problem going on, so when you get to testing, let us know, I'll keep an eye out for your posts, this might be a failed PCM, or vehicle networking issue.
Was this
answer
helpful?
Yes
No
Tuesday, October 29th, 2024 AT 3:28 PM

Please login or register to post a reply.

Sponsored links