2001 Dodge Caravan TPS code

Tiny
CARAVAN2001
  • MEMBER
  • 2001 DODGE CARAVAN
  • 3.3L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 280,000 MILES
After replacing the sensor I am still getting a TPS fault code indicating reference voltage too high. Should be 5 vt and am getting 6 vt. Also the analyzer shows 0 vt on signal but does indicate the degrees of angle. What is next step?
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Saturday, October 17th, 2015 AT 4:37 PM

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Tiny
CARADIODOC
  • EXPERT
Where are you measuring this five volts? One wire on the sensor is fed with 5.0 volts, and another one is the ground, which will actually have 0.2 volts. It's the signal wire in the center the Engine Computer looks at. There's mechanical stops inside the sensor that limit its travel to approximately 0.5 volt at idle to 4.5 volts at wide-open-throttle. Those voltages are approximate. On yours, you might find 0.38 and 4.25 volts, for example, but you'll never get to 0.0 or 5.0 volts.

The only way to get 5.0 volts on the signal wire, which is what triggers that code to set, is to have a break in the ground circuit or the signal wire circuit. The thing you must be aware of is those breaks can be inside the sensor, but it's much more common for it to be in the wire or the connector terminal. When mechanics diagnose this type of fault code, they do electrical tests on the circuit before spending your money on a part.

To be valid, these readings have to be taken with the sensor connected, so you'll have to back-probe through the rubber weather-pack seals in the connector. If you find 5.0 volts on the ground wire, you're going to find it on all three wires. That can only be due to a break in that wire. That isn't too common because it only goes a short distance before it splices into the ground wires for some other sensors.

The fastest way to test this sensor is to measure the voltage on the signal wire. If that goes from around 0.5 to 4.5 volts from idle to wide-open-throttle, it can only do that if the 5.0 volt feed and ground wires are okay, so there's no need to waste time checking them. The sensor is okay too. Now, if you're reading 5.0 volts on a scanner's live data display while you measure 0.5 volts at the sensor, there is a break in the signal wire going back to the computer. Due to the signal wire being interconnected to all the other circuitry inside the computer, the voltage could "float" to some random value, and if it's between 0.5 and 4.5 volts, the computer will see that as an acceptable value and try to run on that. To prevent that and to force it to set a diagnostic fault code, there is a "pull-up" resistor in the computer to put 5.0 volts on that terminal. That resistor is so big electrically that it won't have any effect on a properly-working circuit, but with a break in the signal wire, it will make it set the code "voltage too high". The clue, as I started to describe, is you'll see an acceptable range of voltage at the sensor, but the scanner will show that the computer is seeing 5.0 volts.
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Saturday, October 17th, 2015 AT 9:03 PM
Tiny
CARAVAN2001
  • MEMBER
To answer your question of where I was getting 6 volt reading? It was on the scanners live data display. I'm very thankful for your detailed instructions on the correct way to diagnose this circuit. Wow!
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Sunday, October 18th, 2015 AT 7:50 AM
Tiny
CARADIODOC
  • EXPERT
Keep me up to date on your progress.
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Monday, October 19th, 2015 AT 7:10 PM
Tiny
CARAVAN2001
  • MEMBER
After following your instructions I found reference voltage on both signal and reference wires while back probing TPS plug. It was a little tough to get through the weather seals as you had mentioned. I then started looking for damaged wires since the TPS had already even more replaced. I removed plugs at the computer and ohmed all points in plugs to maybe see if shorted with another wire and a possible clue as to where? I began pondering the thought of running new signal wire to TPS when I began 2nd guessing myself.
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Wednesday, October 21st, 2015 AT 12:57 PM
Tiny
CARAVAN2001
  • MEMBER
I began wondering if I could have got the new and old TPSensor mixed up and accidentally put the bad one back on. I was at a different location and couldn't dig up the other sensor. We managed to find one in my partners garage. Had the same plug, so we plugged it in and started it. Sounded noticeably better. To cut to the ending, the auto parts store solde a bad sensor.
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Wednesday, October 21st, 2015 AT 1:17 PM
Tiny
CARADIODOC
  • EXPERT
Dandy. Happy to hear it was such an "easy" fix. As one very good Chrysler trainer used to tell us, "we not only sell you new parts, we sell them to you pre-broken!" She was referring to new parts that were defective when received from their suppliers. Fortunately that didn't happen real often.

If you want to test the sensors, measure the resistance between the terminals. The exact value is irrelevant but a typical value is around 5,000 ohms. That's between the ground terminal and the 5.0 volt feed terminal. If that is okay, the resistance between the ground terminal and the signal terminal will be a low percentage of that, maybe around 500 ohms or less, and it will increase as you move the lever on the sensor. The resistance should never reach 0 ohms or the maximum, (5,000 ohms in my sad story). There's mechanical stops inside it to prevent that.
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Wednesday, October 21st, 2015 AT 3:48 PM

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