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Torque » Torque OBD ECU Scanner » Torque Discussion / Ideas » Inside a cheap eBay OBD2 adapter - Ford connection problem

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Author	Topic: Inside a cheap eBay OBD2 adapter - Ford connection problem

dan13l

Member
Posts: 3

Re: Inside a cheap eBay OBD2 adapter - Ford connection problem
on: February 10, 2012 (GMT)

Hi,

For the ones interested you may find the ELM327 reference design on ELM site http://elmelectronics.com/DSheets/ELM327DS.pdf. I don’t think that China manufacturer did more than this for the OBD interface, hope is usefull.

Regards,
Daniel

packymann

Member
Posts: 3

Re: Inside a cheap eBay OBD2 adapter - Ford connection problem
on: February 11, 2012 (GMT)

Quote from Monty_ on February 4, 2012

Edit: On the blue arrow heads, you need to scrape off the green solder mask to reveal the copper underneath to test for continuity.

hey,

yes, the red arrows are electronical connected. and the blue arrows too, red with red, blue with blue.
how can I fix the J1850 protocol with this layout?

Tom B

Member
Posts: 10

Re: Inside a cheap eBay OBD2 adapter - Ford connection problem
on: February 11, 2012 (GMT)

I don’t have ford but out of curiosity I’ve taken a look at my ebay adapter. It’s the larger of the two boards discussed here.

It is implemented largely as shown in the manual linked above except for three changes:

1. a transistor group (Q4, Q5, R13, R12, R36, D3) has been replaced with a comparator. A resistor is added between the comparator and the bus negative. (marked R12 on the board)

2. a pull up resistor has been added between bus- and 5v. the 5v is protected from the bus by a diode. (labelled R4 and D3 on the board). I guess this has probably been done to accommodate the the comparator, which would have a higher impedance than the group it replaces.

3. Resistor R6 is missing. This essentially means a digital output pin of the PIC is grounded

additionally the components are labelled differently. here is a list of equivalents:
(on the board vs in the manual)
Q5 Q2
Q1 Q1
U2 U4
R6 R7
R9 R8
missing R6
R14 R5
R3 R3
R1 R4
R2 R2
D2 D2
R11 R9
R7 R15
Q2 Q3
R13 R14
U4 Q5
U4 Q4
U4 D3
R5 R11
R12 added
(R=resistor, Q=transistor, U=Integrated circuit, D=diode)

I don’t see any problem with the comparator modifications so I think the next step would be to add in R6. It should be a 4.6k ohm and could be added as a surface mount to the track just below and right of decal Q1 on the back of the board. (scratch the track clear, cut it, solder the resistor over the cut)

I’m not going to try it myself as my car works just fine with the K-line communication.

Obviously, I take no responsibility if trying this fries your adapter, car or anything else. strictly at your own risk.

tinkertailor

Member
Posts: 1

Re: Inside a cheap eBay OBD2 adapter - Ford connection problem
on: April 26, 2012 (GMT)

Quote from Monty_ on February 2, 2012
I am happy to report that the modification absolutely works, and now I’m a happy camper using a cheap eBay dongle to monitor a 2003 Ford Taurus via Torque Pro.

And also my 2001 Ford Focus! Thanks for posting this.

takee

Member
Posts: 6

Re: Inside a cheap eBay OBD2 adapter - Ford connection problem
on: April 25, 2013 (GMT)

Hi there Folks,

Since several months the new series of cheap v1.5 OBD2 mini BT adapters are out on Ebay. Namely these:

http://www.ebay.co.uk/itm/160877659137?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

Very practical would it be regarding the size.

Well, I’ve just purchased one to see if the SAE J1850 PWM protocol works fine with Fords.

Well, it does not.

I was wondering if there is anybody who might be interested in the modification of this mini adapter. If so, I can rip mine apart and take some detailed pics of the content.

As far as I saw, it’s components are not marked or labelled, so it could be a tricky one.

Anyone?

takee

Member
Posts: 6

Re: Inside a cheap eBay OBD2 adapter - Ford connection problem
on: April 25, 2013 (GMT)

Well, here are the pics.

I see the bluetotth antenna at the top….and there is the line, where my knowledge stops. 😀

takee

Member
Posts: 6

Re: Inside a cheap eBay OBD2 adapter - Ford connection problem
on: April 25, 2013 (GMT)

takee

Member
Posts: 6

Re: Inside a cheap eBay OBD2 adapter - Ford connection problem
on: April 25, 2013 (GMT)

takee

Member
Posts: 6

Re: Inside a cheap eBay OBD2 adapter - Ford connection problem
on: April 25, 2013 (GMT)

Shepherd

Member
Posts: 1

Re: Inside a cheap eBay OBD2 adapter - Ford connection problem
on: May 18, 2013 (GMT)

I have the same one and it doesnt work on my 02 Ford. No one’s found a fix for it yet?

takee

Member
Posts: 6

Re: Inside a cheap eBay OBD2 adapter - Ford connection problem
on: June 9, 2013 (GMT)

Quote from Shepherd on May 18, 2013
I have the same one and it doesnt work on my 02 Ford. No one’s found a fix for it yet?

Sorry mate, no fix for this yet.

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