Help: Retrieving trouble codes on 94

I have been attemptoing to retrieve any problem codes on a 94, I am doing this by jumper wire at the diagnostic connector by the starter. I do not get a response of blinking check engine lite of any sort. Checking the wires at the female connector plug with the ignition switch on I get power on the yellow and white wires but not the blue, which is the terminal wire that is jumped to retrieve the codes. Is there a fusable link somewhere or is this a pcm problem??

Thanks in advance for any advice.

what kinda car is it.. In most cases you can turn the diag screw on the ecm and get your red and green lights to flash on the ecm . to show you your code. Just keep in mind if you do that.. there are 5 modes .. It will blink both lights for the # mode you are on . As so as it goes to mode 5 it will erase all codes stored.. GL

Sorry: It is a 94 MercuryVillager/Nissan Quest. Looking in the Haynes Repair Manual I cannot find any info on this procedure. Is there a link I could use for reference to do this??

Thanks again for any help,
LS

I have been attemptoing to retrieve any problem codes on a 94, I am doing this by jumper wire at the diagnostic connector by the starter. I do not get a response of blinking check engine lite of any sort. Checking the wires at the female connector plug with the ignition switch on I get power on the yellow and white wires but not the blue, which is the terminal wire that is jumped to retrieve the codes. Is there a fusable link somewhere or is this a pcm problem??

did you ever get a solution? my sister is having problems with her 94 Quest and autozone says they can't read code on one that old.