Forestlump
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Hello,
I'm struggling to find the cause, please would someone help?
5.0 2017 manual car with Paxton/ bap, catless Lths, 18 manifold.
Starts and drives fine for about 10 minutes and then get the wrench and airbag light.
Forscan shows codes
p2128 Throttle pedal voltage correlation
p2138 Throttle pedal voltage high
b00A0 Occupant classification system
U0401 invalid data from ECM/pcm.
codes all reset once car has cooled down and stay off until it warms up again.
on the oscilloscope on Forscan I can see the point at which the fault happens, throttle pedal voltages APP1 + 2 are smooth and zero error untill that point (after driving for about 10 mins). Then the voltage from APP2 jumps 1.5v and the error goes full scale and car goes in to limp mode. APP2 voltage is then bumpy/ dirty and codes won't clear until it cools down again.
It's like something switches on after a while and is dragging down the 5v but only on Throttle pot APP2. Though the 5v ref never wonders from 5.01v (I'm wondering if there is 2 5v busses and something on bus 2 is shorting)
Battery is mint, connections are all clean.
Changed pedal for low milage ford spare but fault is identical.
Disconnected rear O2 sensors, vortech bap, A/c pressure transducer, still the same.
disconnected passenger seat.
checked all wiring, as far as possible.
With the Forscan oscilloscope showing throttle voltages and when the faults triggered, I've disconnected near enough everything related to the 5v to see if it's a short but nothing clears it.
Any ideas?
I've read of an identical fault but the guy traded in the car before finding out what it was, ford had replaced pcm and diagnosed the loom. I'm 100% it's not the loom as it's repeatable.
See oscilloscope of throttle voltages
APP1 (Red)
APP2 (GREEN)
pcm throttle command (blue)
Throttle pots error (purple)
Any help would be gratefully received.
I'm struggling to find the cause, please would someone help?
5.0 2017 manual car with Paxton/ bap, catless Lths, 18 manifold.
Starts and drives fine for about 10 minutes and then get the wrench and airbag light.
Forscan shows codes
p2128 Throttle pedal voltage correlation
p2138 Throttle pedal voltage high
b00A0 Occupant classification system
U0401 invalid data from ECM/pcm.
codes all reset once car has cooled down and stay off until it warms up again.
on the oscilloscope on Forscan I can see the point at which the fault happens, throttle pedal voltages APP1 + 2 are smooth and zero error untill that point (after driving for about 10 mins). Then the voltage from APP2 jumps 1.5v and the error goes full scale and car goes in to limp mode. APP2 voltage is then bumpy/ dirty and codes won't clear until it cools down again.
It's like something switches on after a while and is dragging down the 5v but only on Throttle pot APP2. Though the 5v ref never wonders from 5.01v (I'm wondering if there is 2 5v busses and something on bus 2 is shorting)
Battery is mint, connections are all clean.
Changed pedal for low milage ford spare but fault is identical.
Disconnected rear O2 sensors, vortech bap, A/c pressure transducer, still the same.
disconnected passenger seat.
checked all wiring, as far as possible.
With the Forscan oscilloscope showing throttle voltages and when the faults triggered, I've disconnected near enough everything related to the 5v to see if it's a short but nothing clears it.
Any ideas?
I've read of an identical fault but the guy traded in the car before finding out what it was, ford had replaced pcm and diagnosed the loom. I'm 100% it's not the loom as it's repeatable.
See oscilloscope of throttle voltages
APP1 (Red)
APP2 (GREEN)
pcm throttle command (blue)
Throttle pots error (purple)
Any help would be gratefully received.
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