Grand Marquis chooses when to start
Asked by Thomas Dec 31, 2022 at 10:59 AM about the 2004 Mercury Grand Marquis GS
Question type: Maintenance & Repair
Built in 2004, but some parts fit as 2005.
ISSUE: Two months back, she wouldn't start occasionally. Cold mornings, she
would never start on. At that time, turning the key in the ignition rendered one
click. After the below items were replaced or checked, I got several clicks.
TIMELINE:
1. Starter checks out well.
2. It started well on a new battery, but now it won't crank 10 hours after the
installation. The gauge inside reads as Low. BUT, the air blows at total capacity
along with the dash and headlamps.
3. Throttle position sensor was replaced, and the throttle was cleaned.
After each attempt of repair, she would start several times like a champ, then
stop the next day.
GOING FORWARD:
I'm left to consider the alternator, transmission range sensor (neutral safety
switch), or fuel injector sensor.
PLEASE; have any thoughts or similar experiences?
9 Answers
NOTE: Shifting to neutral and turning the key had helped at one time, but no longer the case.
These vehicles are known for electrical problems in the instrument cluster area. It sounds like a bad ground. The light control module is another trouble spot with these vehicles. As well as the control module for the automatic climate control system. However, since these problems, I'm assuming, started happening together, I'd suspect a bad ground first. Most likely under the dash. Hope that helps! Jim
Trippmeister answered about a year ago
How good are your battery cables? Corroded? Try replacing both of them. Bad ground somewhere sounds likely. Also check the ground cable from the engine to the frame.
The cables were replaced. Grounds check out. The starter is getting juice from the battery. I did see the trigger wire to the starter wasn't getting juice. I went to the steering column and checked the continuity of the ignition switch harness. It had continuity. Thinking it must be the transmission range sensor that is not allowing it to pass onto the starter. Thoughts?
Trippmeister answered about a year ago
I think you're onto something. Neutral lockout switch? Does the car have a security system?
Neutral saftey switch replaced. Also replaced the Automatic Transmission Input Sensor for the heck of it. - Still no juice to the trigger wire.
The theft light flashes quickly when the key is in the "ON" position. My understanding is that there is a fault related to the PATS system.
Trippmeister answered about a year ago
Try googling it. I don't know much about it. Insert the key into the driver's side door lock. Turn the key once, but not all the way to unlock the door. Leave the key in this position for 40-60 seconds. ... Do this again, but turn the key in the opposite direction. Remove the key from the door, get into your Ford, and start the engine. The system should be reset.
That's correct. On a Ford Product you need two working keys to program additional keys to the vehicle yourself. Sounds like this is a job for your local Ford Dealer or a reputable locksmith. Jim
