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2013 ST2, AGP BWS turbo, long block
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The question is. Why is my PCM sending 4.8v out on an input wire.
Why does it have voltage on a wire that is supposed to receive signal voltage from a sensor.
Its a brand new PCM. How is that even possible
 

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2017 Kona Blue ST1
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Are you measuring that voltage at the TB connector or back on the PCM Pin 81 Green Violet?
 

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2013 ST2, AGP BWS turbo, long block
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This is with the PCM plugged in, and I'm using TB pin 4 (ETCRTN) as the (-) lead and pin 6 (TP2) for the positive lead and seeing 4.8 volts.

Last we talked, I cut my pin 6 wire very close to the PCM large connector and tested to see if I still got the same result at the start of the wire. I indeed saw 4.8 volts there as well.
 

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2017 Kona Blue ST1
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Stupid question, what the voltage on Pin 3?
 

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The C1035C is a common issue due to heat, vibration & moisture. The throttle is a direct connection to the PCM but the APP (accelerator pedal position) must pass through the connector at the BJB (battery junction box) to make it back to the PCM.

For the throttle Pin 5 is the 5 VDC + VREF and Pin 4 is the SIGRTN -
Pins 3 & 6 are the signal return back to the PCM.
Pins 1 & 2 are the control motor. Do not try and measure these Pins with a DMM.
[/QU
Is the #5 wire on the tps connector the 0-5v signal wire? Rising voltage/positive slope? I'm trying to connect a WOT switch. Any help is appreciated! Also is the 3rd wire to the right on a coil pack the negative wire for rpm signal?


OTE]
 

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@fenderfarney

So the issue here how a potentiometer functions. Power into the sensor (VREF), Ground (RTN) & output from the sensor to the PCM.

As the sweeper moves with the throttle shaft it varies the output to match the throttle blades position.

The two internal sensors share a single VREF & SIGRTN source. It this were bad other codes would generated.

TP1 (NEGATIVE SLOPE) should show VREF +/- at rest back to the PCM

TP2 (POSITIVE SLOPE) should should less than 1VDC at rest back to the PCM

That how these sensors function.
The reason why you don't test against your 12 VDC terminal Positive or Negative) is because unlike other circuits in the PCM the electronic throttle control is handled by a microprocessor. Other various systems use a clean ground that helps to filter out various electrical noise.

If the Sensor is seeing voltage on the VREF & Output then it will show a circuit high and trigger a CEL.
 
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Premium Member
2013 ST2, AGP BWS turbo, long block
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I'd like to sincerely thank everyone who helped me troubleshoot this. Car has been running well for 3 months now with no TB issues. The support was very nice as the issue was extremely confusing.

Ended up determining that between my 3 Throttle bodies, the two new Mustang TBs had bad TPS sensors (TPS sensor is built into cover) and the Mustang TB I had in my car had a bad servo.

When I was troubleshooting the system, the TB with the bad servo may have damaged the PCM's controller for the throttle body.

Best way to solve Throttle body related issue like this is to leave the PCM out of the picture.
Test Throttle body first. Use a 9 volt battery to actuate the motor leads. With a 5 volt power source (stripped iPhone charger), power the TPS sensor and use a DMM to verify that it works. If the throttle body operates properly on a bench, then proceed to troubleshoot the wiring harness. PCM last. Its expensive if you break it.
 
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