WHY WOULD TPS SIGNAL WIRE HAVE 4.8 VOLTS COMING FROM THE ECM?

  • Tiny
  • pelwynf2009
  • 2000 Dodge Neon
  • 165,000 miles

Is there a limp mode that does this or is it a short coming out of the ECM? My understanding is that this wire is read by the computer and there isn't supposed to be voltage coming out of the computer through it. I'm not sure if the car will do this for a reason or if I have a short.

I get the same results with two different computers so I'm pretty sure it's not the problem. Should I start testing every plug on the car with an ohm meter to find a short. I have been digging on this for quite some time... Please help.

Monday, April 23rd, 2012 AT 12:18 AM

7 Answers

  • Tiny
  • ASEMaster6371
  • Expert
  • 25,549 posts

Computer sends a 5 volt signal down the line to the sensor. There is a ground wire and a sensor return wire back to the pcm.

Roy

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Monday, April 23rd, 2012 AT 12:22 AM
  • Tiny
  • pelwynf2009
  • Member

I understand, when the sensor is unhooked the sensor return wire reads 4.8 volts from the computer. 5 volt supply wire and ground wire are normal.

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Monday, April 23rd, 2012 AT 12:26 AM
  • Tiny
  • ASEMaster6371
  • Expert
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That is normal also.

Roy

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Monday, April 23rd, 2012 AT 12:36 AM
  • Tiny
  • pelwynf2009
  • Member

So, testing the tps plug with the key on and the tps unhooked I have 5 volts, 4.8 volts, and ground. That's normal? Why would the computer send 4.8 volts out the signal wire. Shouldn't that wire be an input to the comp not an output?

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Monday, April 23rd, 2012 AT 12:58 AM
  • Tiny
  • ASEMaster6371
  • Expert
  • 25,549 posts

The return signal when hooked up will lower the voltage back to the pcm.

Roy

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Monday, April 23rd, 2012 AT 12:59 AM
  • Tiny
  • pelwynf2009
  • Member

I noticed that earlier. Thanks, as long as I know that it's acting normal.

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Monday, April 23rd, 2012 AT 1:04 AM
  • Tiny
  • ASEMaster6371
  • Expert
  • 25,549 posts

Good luck

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Monday, April 23rd, 2012 AT 1:05 AM

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