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How to Read FD Trouble Codes

Old 08-23-13, 08:10 PM
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Proves the problem is NOT in the ELU, but in the PCME fault detection circuitry or in one of the input signals to the PCME. One would think that if a sensor was at fault, a trouble code would appear rather than a constant low FEN voltage. It's not the PCME output shorted since it can go to 11 volts. It must be a fault inside the PCME.
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Old 08-23-13, 11:15 PM
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Originally Posted by wstrohm View Post
Proves the problem is NOT in the ELU, but in the PCME fault detection circuitry or in one of the input signals to the PCME. One would think that if a sensor was at fault, a trouble code would appear rather than a constant low FEN voltage. It's not the PCME output shorted since it can go to 11 volts. It must be a fault inside the PCME.
hmmm...

we have already tried swapping the PCME to another PCME with the exact same result.

I guess this means we're looking for a bad input, rather than a bad output from the PCME? We were going to check the X-07 connector, but sounds like from what you're saying that won't show a problem either.
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Old 08-24-13, 06:00 PM
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No further ideas here; looks like a puzzle for a digital processor expert. The action you see sounds as if the PCME initially sees no fault (terminal 1F goes high) and then decides there is a fault that deserves a constant CEL and sets 1F low. Don't know what that fault would be.
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Old 09-13-13, 01:38 PM
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Originally Posted by joelanger View Post
so how do you do this on a JDM model with no 'check engine light'?
On the diagnostic box connect the positive end of the LED, with a 500 ohm resistor in series to the 'B+' terminal. the negative side of the LED should go to the 'FEN' terminal

With this set-up works just the same then as above, using your LED as the CEL

I used some pre-wired LEDs from ebay (5 for 99p or like $1.50) that then didn't need the resistor in the line.

might be worth adding this in the top mate to help any other JDM rotor head out!!
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