1990 Ford Ranger ECA or Electronic control assembly

DCT

MEMBER
1990 FORD RANGER
2.9L
V6
RWD
AUTOMATIC
100,000 MILES

Code 54, replaced with 3 different new sensor's.
Still have code.
Cold engine check voltage out of ECA at pin 25, some times it's 8.5 volts or even 12 volts this is on a 90 degree day!
All wires checked and good.
Pin 26 or reference voltage is steady at about 5 volts! Even when pin 25 voltage is all over the place!
Engine start up great! About 10 seconds after running it will make a check engine light!
And most of the time it will stop check engine light after running to operating temp.
When checking volts at pin 25 (signal wire.) When check light goes out, voltage might be 3 or 4 volts.
My guess is the computer is bad!
Thank you to any one who can tell me if voltage on pin 25 is over, 5 volts. Or more, the computer is bad.
So I won't waste more time and money on parts I don't need!
Thank you again.
Dan T

2 Replies

WRENCHTECH

MECHANIC
20,757 POSTS

It sounds like you have either a bad connector of a problem in the wiring between the sensor and the computer. Compare voltages at the sensor itself and the same wire at the ECM.

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Monday, May 19th, 2014 AT 2:40 PM

DCT

MEMBER
1 POST

Thank you,
I have checked the voltage at the sensor and computer already even with the wire cut off at the computer to make sure no short or bad wire in harness. Same voltage.
So, it seems if the voltage is ever over 5 volts, like over 6, 7, 8, 9, 10, 11, volts like I'm seeing with a good volt meter. Right at the computer pin 25,
it seems like it has to be a bad computer?
Pin 26 on computer ( reference voltage is steady a about 5 volts all the time ) even when the voltage is at 11 or even 12 volts on pin 25 signal wire.
And good at pin 46 signal return wire is good also.
All wires seem good with me even twisting the ( $hit out of them at computer and harness ) LOL
And checking there ( continuity measurements )
Thank you all.