1997 Mercury Marquis



June, 5, 2009 AT 7:21 PM

Electrical problem
1997 Mercury Marquis V8 Two Wheel Drive Automatic 126000 miles

I have a 1997 Mercury Grand Marquis that I am working on and I cannot get it to start. The car ran fine until one day when I came out and I did not hear the fuel pump pumping. The things I have tried so far are:

-new fuel pump
-pulled all fuses and maxi fuses
-new fuel pump relay
-checked for Voltage at Throttle Position Sensor (none)
-traced as many wires as I can think of for voltage and resistance
- connected a brand new Scan Tool only to see it's not detecting being connected to car (plugged the scan tool into another car and it worked fine)
-swapped PCM with a used one (still no fuel or communication to scan tool)
-tried starting fluid in intake
- pulled one spark plug wire from plug and connected spark tester and got no spark
- checked #16 pin in data link connector for voltage and #5 for ground (seems okay)
- I am pretty sure I heard the PCM relay clicking when I turned the key to the ON position.

I am about out of ideas. Anyone have any suggestions?


3 Answers



June, 6, 2009 AT 5:33 AM

Turn key on do you have check engine light on
if not PCM have no power
check for an open wire and or fuse 1st
use a test light check fuse #7 its 25A under dash it should be live with key on

let me know

need manual CHECK IT @



June, 6, 2009 AT 2:09 PM

The check engine light was not on. I pulled the fuse and there was power. I checked for power from there to the diode in relay center, from the diode to the relay, and to the y/br wire on the other side of the relay. All had power. At one point, the check engine light was flickering when I had reinstalled the #7 fuse, but it has not done it again.



June, 6, 2009 AT 6:30 PM

Do wiggle the wiring harness and have a helper watch the light for you
trying to pin point the area where the light flicker
check the wiring and fuse terminals

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