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Sunfly
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by Sunfly » Thu Apr 30, 2020 6:07 pm
I've got an analogue multimeter on order for tomorrow to check for codes. Has anyone tried this method as recommended by Ford and does it work OK. I assume correct polarity will be needed with a multimeter on dc but does it matter with a diode. I've only ever heard the club talk about a diode test.?
Secondly, I am sure I've seen posts in the past about code retrieval procedures, but look as hard as I can, I cant find any. Can anyone help with an engine diagnostics procedure.
I want to check things through before disconnecting the battery for a little problem I've got...
Ta,
Bob
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Micron
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by Micron » Thu Apr 30, 2020 6:14 pm
Bob,
I have only ever known the diode method of doing it, never tried a meter, do you have a process to go with it?
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jrh
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by jrh » Thu Apr 30, 2020 6:51 pm
I would be a bit nervous using a multimeter ! They can impose quite a load on the device (ohms/volt) .
Dead easy to make up the LED tester +4.7k resistor and the straight wire link and count the 'dots and dashes'.
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Sunfly
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by Sunfly » Thu Apr 30, 2020 9:35 pm
Micron wrote: ↑Thu Apr 30, 2020 6:14 pm
Bob,
I have only ever known the diode method of doing it, never tried a meter, do you have a process to go with it?
I got it from the bible, where they give you the option of a Star tester or a VOM multimeter, presumably "Volts Ohms meter" which they advise you to set to the 20 volt range. but in answer to Johns comment about current draw, they dont specify any constraints on the multimeter, so I took that to mean that the pcm is robust enough to be ok. They dont mention using an led test at the diagnostic box but they do specifically warn against testing the pcm with a "lamp". No doubt they meant a tungsten filament lamp but when did led's come in, were they about in 1996? I thought late 80's.
So John, if I need to make up a diode test, whats the resister for and is it in series or parallel with the diode and whats the spec of the diode?
And is there a procedure that anyone can point me to?
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jrh
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by jrh » Fri May 01, 2020 7:34 am
Best to look at the plan view of the diagnostic socket in your wiring diagram book.
Then, a piece of stiff wire loops between GND and TEN
The +ve leg of the LED goes in B+ the other leg in FEN.
The 4.7k resistor can be in either leg of the LED.
Read the Morse code flashes.
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jrh
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by jrh » Fri May 01, 2020 9:26 am
Secondly, the reason why I think the LED method is better , no 'inertia' to overcome !
The gaps between driving the voltmeter pointer 'up' may not be long enough i.e. will look like a series of 'dots' with no 'dashes'.
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mojo98
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by mojo98 » Fri May 01, 2020 9:52 am
I have a Star test machine, which I purchased off Brian O'keefe a few years ago.
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Sunfly
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by Sunfly » Fri May 01, 2020 10:40 am
Thats the page - Section 5-12 of the system test manual (Quick test procedures).
Now I've looked again it doesn't beat about the bush... It says you can do it with an analogue voltmeter and I like that idea as I can use it to check out other things if I leave it permanently in the car. (on trips) Having said that, the very reason I asked my question was that I didn't want to screw things up if there was a very good reason anyone knew for not doing it this way.
So I've got two options now. Try the voltmeter or the diode (when I get one),
On that subject John, I'll just check with you that the resistor is in PARALLEL with the diode. I ask because I've not heard of anyone using the resistor before, and so I've always assumed that only the diode was required.
Last edited by
Sunfly on Fri May 01, 2020 11:25 am, edited 1 time in total.
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Micron
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by Micron » Fri May 01, 2020 11:11 am
Bob,
I have a diode reader, and I think maybe some instructions, but as they are over at the workshop, I might not get them until later today if you can wait a bit?
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Sunfly
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by Sunfly » Fri May 01, 2020 11:29 am
Micron wrote: ↑Fri May 01, 2020 11:11 am
Bob,
I have a diode reader, and I think maybe some instructions, but as they are over at the workshop, I might not get them until later today if you can wait a bit?
Yes no problem Trev. I've got a fault somewhere on the fuel system so I was going to look at it tomorrow if the weather behaves itself.
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