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Reading DPFE voltage using OBD-II PID

I back probed the connector on the DPFE referenced to SIGRTN , Vref =

5V, DPFE = 2.39V (zero delta pressure - both ports open to air). The DPFE voltage should be < 0.6 volts with a zero delta pressure therefore the DPFE is defective. I also applied pressure (output voltage lower) and vacuum (output voltage higher) to the reference port, this shows the DPFE is still responding but has a killer 2.4V offset rendering it usless in the application.

I would like to read the DPFE output voltage using my ELM320 scantool to verify the ECU is reading about the same voltage as my DMM. I had very good success troubleshooting an intermittent HO2 sensor failure by logging data using a program I wrote to drive the ELM. But I cannot find good helpful information regarding the PID for the DPFE.

The best I came up with is this...

0645
46 45 20 7F 32 CB 40

Mode $06 - PID $45

I replaced the DPFE with a pot and input a range of voltages to the ECU and tried to correlate this to the ELM response(s) but without knowing the data position and the bit width it becomes rather frustrating. The data in the 2 right-most bytes changes when I change the voltage but I'm not sure if I'm looking at the right data fields.

If anyone can tell me if this is the correct mode and PID and how to determine the voltage from the data string that would be nice.

Thanks DC

Reply to
stlham59
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According to my book, the PID for DPFEGR (in Volts) is 114E (hex, I suppose). No clue about mode or how to convert the result to volts -- my scanner just reads this with directly, with no need to enter modes or anything else... HOWEVER, unless you are doing this as an intellectual exercise, it's not worth struggling. Your DPFE is dead -- a very common problem.

...

Reply to
Happy Traveler

Dear HT,

Yes it is an intellectual exercise...

Thanks for the 114E (that's HEX hence the "E") I will give that a try.

BTW, a couple further questions.

1) What book are you looking at? 2) What scanner are you using?

Thanks, DC

Reply to
stlham59

My source of information about those things is the so-called Volume H of the Ford shop manual, officially called "Powertrain Controls/Emission Diagnosis". In print it's fairly pricey, but slightly out-of-date versions can be had for a song on DVD -- together with a bunch of other manuals. Last time I looked Ebay was flooded with those.

I am using an EASE scanner. Bought it quite a few years ago. This company addresses mainly the professional market, and their DIY line seems both overpriced and under-capable today. I never upgraded it with their 'body and chassis package', because it would have been a fortune. There almost certainly are better choices today. In fact, I am looking at AutoEnginuity (sp?). If anyone lurking here has experience with those, primarily with their extended capabilities like ABS, climate control, etc, I'd like to hear from you.

Reply to
Happy Traveler

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