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Discussion Starter · #1 ·
i have been running threw every possible scenario for the p1401 weather it is a alt voltage to high which i do not think it is now. here is what i did to get that code to go away lol'z. i jumped the brown wire white stripe at the tps sensor to the dpfe brown wire white stripe. now the code is gone but getting a different code p1120 pd there is reason for this.

btw just capped the brown white wire at the dpfe. the dpfe code is gone but the throttle position sensor low voltage input is up. most likely because i spliced in to it. according to my diagrams in my Haynes they are all connected off the brown white wire. the tps sensor the dpfe sensor and the fuel tank pressure sensor. so if i jumped it it should still work right? unless they got separate wired to each sensor so does that mean to rip the intake manifold upper of course and see what is going on under it?


any help would be appreciated cause it is a common wiring problem i am thinking.
 

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What is the voltage coming from the DPFE going to the PCM?


Diagnostic Trouble Code (DTC) P1401 indicates that Self-Test has detected DPFE SIG circuit input above the maximum.

Possible causes:

-- DPFE SIG open.

-- DPFE SIG shorted to VREF or PWR.

-- VREF shorted to PWR.

-- SIG RTN open.

-- Damaged D.P.F. EGR sensor.

-- Damaged PCM.
 

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Discussion Starter · #3 ·
What is the voltage coming from the DPFE going to the PCM?


Diagnostic Trouble Code (DTC) P1401 indicates that Self-Test has detected DPFE SIG circuit input above the maximum.

Possible causes:

-- DPFE SIG open.

-- DPFE SIG shorted to VREF or PWR.

-- VREF shorted to PWR.

-- SIG RTN open.

-- Damaged D.P.F. EGR sensor.

-- Damaged PCM.


the voltage is about 5.64 volts out of the pcm which is vref there is no way the vref is shorted to power. sig can not be shorted to v ref or power . what i am wondering like i always have is if it is the pcm being damaged. the wire that supplies reference voltage to the sensor is out of spec coming out of the brain / pcm which makes me think it is the pcm. by being out of spec all it can be is off plus or minus .1 volt of 5 .0 volts.so if it is 5.2 it's off. this is what made me thing the voltage regulator on the alt could be bad on the alt but i doubt it. leading me to think it is the pcm.cause i checked every thing posible i got two dpfe sensor laying around that are good. sig return may be open but i do not think it is

thanks for your help it is much appreciated
 

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My 5V was always just under 5V, ~4.8v. A good place to check is the TPS sensor.
 
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